Natural Hazards 2007 A review of the major hazard events of 2007, and the work of NIWA, GNS Science, and other organisations in their efforts to reduce the risks, and mitigate the effects, of natural hazards in New Zealand.

More than a can of beans Disaster preparedness is a complicated business. There’s much more to it than stashing away a few cans of baked beans. Even an apparently simple matter like motivating people to create and maintain a household preparedness kit takes some smarts. The Ministry of Civil Defence & Emergency Management (MCDEM) demonstrated that last year in making the best use of heightened awareness after the Gisborne earthquake by rapidly implementing a public advertising campaign. This second annual Natural Hazards Review again highlights the range of natural hazards we experience in New Zealand: everything from lahars to coastal erosion. New Zealand scientists are working hard on answering fundamental questions about our natural hazards and taking this information all the way through to forecasting hazards and calculating likely risks. It’s smart science. An international expert review in October last year judged the NIWA weather and flood forecasting modelling systems now in use here (see pages 20–21) to be world class; and the same review panel stated that GNS Science’s Geological Hazard and Society programme (see pages 22–23) was a leading contributor to international best practice for science and application. We’re also using our expertise and knowledge to help develop science capacity internationally. I have seen first hand the valuable contribution GNS Science is making to developing Vietnam’s capacity to undertake tsunami hazard and risk assessment. And science can contribute still more to better understanding of the risks of natural hazards and to reducing the impact of these hazards on people and infrastructure. There’s a challenge here for central government: to maintain support for natural hazards research. But arguably the most vital link is getting the information to the people who need it in a clear and usable form. This review lists dozens of publications produced by scientists from the Natural Hazards Centre (GNS Science & NIWA) over the past year. I commend them for working closely with regional councils, MCDEM, the insurance industry, EQC, the Ministry for the Environment, and others across all of government and in the wider emergency management sector. This review is a great demonstration of their commitment to helping New Zealand get ready, get prepared and get thru.

Hon Rick Barker, Minister of Civil Defence & Emergency Management

2 Natural Hazards 2007

Contents Hazards summary 2007 4–12 Volcanic activity 4 Landslides 4 Focus on …Mt Ruapehu’s lahars 5 Heavy rain & floods 6 Drought 6 Focus on …the Northland floods 7 Earthquakes 8 Tsunami 8 Focus on …the Gisborne earthquake 9 Wind & tornadoes 10 Coastal hazards 10 Focus on …the Taranaki tornadoes 11 Snow, hail, and electrical storms 12 Temperature 12 Insurance 13–14 2007 – an expensive year [Insurance Council] 13 The Earthquake Commission in 2007 [EQC] 14 Guidelines to assist natural hazards planning 15 Did you know …? 16–17 Government departments & hazard planning 18–19 Nine hundred civil defence events [MCDEM] 18 Developing a nationwide flood risk management policy [MFE] 19 Research in 2007 20–25 Validating our weather hazards forecasting model 20 Geological hazards and society 22 The Regional Riskscape Model 24 Publications in 2007 26–29 Selected hazard research publications 26 Selected hazard studies 28

Contributors 30 Acknowledgments 31 Natural Hazards Centre courses and conference in 2008 31 Resembling more a lake than a farm, Hikurangi Swamp soon after the July 2007 weather event in Northland. [Photo: Northland CDEM Group]

Natural Hazards 2007 3 4 Hazards summary Natural Hazards 2007 Volcanic activity Landslides Source: GNS Science GNS Source: site Malfroy’s of Gardens. Government in the Geyser former in late the Juneat asmaller occurred and one Stream, 2007. Puarenga the of 27 on mouth was the May at first The Two in Rotorua during occurred small eruptions hydrothermal by 25 m, remains low. and receded had level water 2007 Bythe March evaporated. water the to fall as level the began and to over ºC rose 60 then lake temperature The 2006. in within February overflow to 1mof reach rose lake level water The crater in the since 2000. erupted not has volcano, active White Island,New Zealand’s frequently other eruption. an without and parameters monitored any in without changes but since 2000, observed have been volcano, shallow of significant numbers volcanic earthquakes At continued. Tongariro in 2006 began that seismicthe unrest T lake crater failed. the of outlet natural the blocking dam 18 on tephra earlier year in the the when March lahar occurred break-out small much anticipated The lahars. several summit withvolcanic caused the of and area debris, much lake bombarded the of that north to the ablast generated 25 This on lake Ruapehu September. crater Mt at active the through volcanic eruption an event 2007 of largest was The Whiteand Island. Ngauruhoe Mt at signs and Ruapehu unrest of Mt from eruption inNew Zealand’s2007, active were volcanoes withasmall Source: GNS Science GNS Source: Wanaka. Lake of head the at Makarora of 29 on Young August in the second the and River west Cook Mt near 5March on landslides, first two the detected network year. 2–3 avalanches every 2007 In Alps the rock is detecting Southern in the network seismograph GeoNet upgraded The tsunami. resulting in asmall landslide-generated lake, crater the landslides entered these of largest and first The White on Island. area crater the from landslides reported were 10–12 On September. and March small of anumber November volcanicor activity, including in Ruapehu Mt on lahars the with volcanoes landslidesof inA number 2007 were associated 20 on December. earthquake Gisborne 6.8 magnitude to the falls landslides or attributable rock of in reports no were Fiordland. Sound There George near 16 on 6.7 October 30 January, earthquake amagnitude and Island on Raoul near earthquake falls 6.5 rock –amagnitude small to cause enough shaking strong Two caused earthquakes 28–29 10–11on and March July. Buller in were the 17events on region in Northland and March rainfall. significant most high-intensity The localised particularly rainstorms, landslides of was trigger common most The by National fallingclimber Park killed was Cook in Mt rocks. a March In volcanic and eruptions. by rainstorms, earthquakes, triggered were and Zealand New throughout occurred These over 100 significant landslides in 2007. recorded GNS Science here have been no eruptions at Mt Ngauruhoe since 1977, Ngauruhoe Mt at eruptions no havehere been but 2007 – the year of the lahar At 10:22 on 18 March 2007, one of the most anticipated geological events of the past decade finally happened – the fragile dam of rock and ash holding back Mt Ruapehu’s summit crater lake gave way. 1.3 million m3 of warm acidic water gushed out, forming a volcanic mudflow or lahar.

The torrent rushed down the steep Whangaehu gorge on the eastern flank of Mt Ruapehu, entraining five times its weight in rock debris. Within 15 minutes, it had reached the Round-the-Mountain track, 7 km downstream. A sensor array, installed and operated by GNS Science and Massey University, measured the lahar’s peak depth at over 8 m, and the ground shaking associated with the flow. Further sensors and observation teams at multiple locations downstream were able to track the evolution of the lahar from its initiation right to the coast, 155 km away, where it arrived 16 hours later. This, and other parts of the comprehensive science programme developed by New Zealand researchers in the lead-up to the lahar, has captured arguably the world’s most complete dataset on a single lahar event. The possibility of a lahar was predicted a decade in advance, so a state-of-the-art early warning system (ERLAWS) was put into place by the Department of Conservation and a consortium of local government bodies, emergency services, and infrastructure agencies. A combination of pre-emptive engineering measures, including raising and strengthening the SH47 road bridge at Tangiwai, construction of a bund at the mouth of the lahars Ruapehu’s Mt on Focus Whangaehu gorge, and installation of gates and warning lights on roads crossing the river, coupled with flawless functioning of the warning system and the actions of responding agencies on the day, resulted in no casualties and minimal property damage. This was in direct contrast to the 1953 Tangiwai disaster, when a similar break-out lahar critically damaged a bridge minutes before arrival of the Wellington-Auckland express train, which plunged into the river with the loss of 151 lives.

A blue sky eruption On 25 September, just as the mud from the March lahar was drying, Mt Ruapehu came back to life with an unforeseen or ‘blue-sky’ eruption through the crater lake. Lahars were triggered in two catchments by water thrown out of the lake basin landing on the snow-clad summit of the mountain and running down its flanks. A climber in Dome Shelter, which is about 700 m from the centre of the crater lake, was seriously injured when the shelter was hit by a boulder. A small snow- slurry lahar travelled about 1 km down the Whakapapa skifield near the Far West T-bar, while several larger flows occurred in the Whangaehu valley. These flows were radically different from the March lahar, consisting of 80% or more snow, with the balance being crater lake water and rock debris. They did not travel nearly as far as the March lahar. Research on all of these events is ongoing, and is already shedding new light on lahar processes and hazards at Mt Ruapehu, New Zealand’s most active onshore volcano. Trail of the MarchTrail 18 lahar. [Photo: Manville, Vern GNS Science]

Natural Hazards 2007 5 6 Hazards summary Natural Hazards 2007 Heavy rain &floods Drought Canterbury on the 8 October. 8October. the on Canterbury in North and Valley 7 October on in Hutt areas catchment rainfall substantial events, occurred notable other Amongst Island. Stewart of parts affected Taieri Dunedin, and High rainfallOtago, slips and districts. also sites North 100 in recording the several mm at exceeded Rainfall Dunedin. of south and north SH1 both closed was their homes. from evacuated people and were flooded rainfall. Roads heavy of 30 July the on because Otago and Canterbury in South declared was civil of emergency A state streets. and bridges, roads, several blocked army, by the schools floodwaters country as flooded two from Children evacuated were 24 areas. in some hours 150 within and hours, 48 mm within reported mm rain of was During 17–18 rain fell Julyin Hawke’s heavy Bay. Up to 300 city. the of parts in some knee-deep was water and into sea, the and downstream swept was acar Plymouth New In evacuated. 22–23 May, houses and closed businesses and withschools rainfall during heavy Taranaki and Nelson of experienced Parts 5–7February. during flooding also experienced life. everyday Northland and to disruption businesses low-lying of serious land, and flooding away,even washed large-scale was there drowned, were stock and Buildings, flooded were roads areas. and in homes, some 10–11 records previous rainfall July. exceeded far cases both In over 28–29 which of and worst in were Northland March the in 2007, incidents nineflooding serious least at were There Centre Climate NIWA National Source: Zealand, forexample: much New of Annual rainfall throughout average below was lambing and beef population, costing more than $500 million. shortage of feed for livestock, and a lower than normal spring Wairarapa, as well as Central Otago. This resulted in a severe Significant soil moisture deficits occurred from Gisborne to low May rainfall occurred in many northern and eastern regions. Island until May. North the of Record east in the which persisted 2007 began with low rainfall and significant soil moisture deficits Centre Climate NIWA National Source: Plenty, Taranaki, Wairarapa, Manawatu,Nelson. and 110 (more than deficits mm) in Auckland, occurring Bay of withsignificant soil moisture Otago, Central and North and Canterbury, in Marlborough, December through November 130 (more than soil deficits Severe moisture from mm) persisted February. during Otago Central and Auckland, of in Nelson, North and 10 than Less in years. parts mm rainfall of 80 also occurred in over there February normal, of Tekapo driest Lake at –the 291 rainfall only year. mmtotalled for 0.4the mm, February 1% withonly years, 60 than in year more driest its recorded Lauder record. on year their driest recorded Many locations Marlborough, of in parts 60% normal of than • less • less than 75% of normal in the east from Wairarapa from 75% to than • less east in the normal of Canterbury, and Central Otago. Central and Canterbury, Wellington, Nelson and Bay Plenty, of Taranaki, eastern Otago, Manawatu, Gisborne, The March ’07 Northland floods – a 1-in-150 year event On 28–29 March 2007, over 400 mm of rain fell in hill catchments of eastern Northland. The rain was caused by moist subtropical air masses from the northeast being pulled south across the Northland region – the result of an active depression moving southeast from the north Tasman Sea being ‘squeezed’ against a blocking area of high pressure to the east of New Zealand.

Severe weather warnings had been issued, but total rainfall greatly exceeded expectations and 1-in-150 year AEP (annual exceedence probability) rainfall occurred in Kaeo, the hills west of Kerikeri, and the hills north of Whangarei. The heaviest rain fell for over 8–10 hours; rainfall intensity was also extreme, with over 40 mm falling in an hour at some locations. In the Hikurangi area, the Wairua River rose 3.5 m in two and a half hours. Low-level flood protection schemes were overwhelmed, floodwater covered more than 5000 hectares of farmland, and large areas of pasture were destroyed. Further north, a number of rural communities were badly affected, and some homes were condemned as a result of flood damage. Numerous landslides occurred; the most serious undermined or engulfed buildings, damaged main access routes, and closed tourist attractions. The residents of Whangarei were fortunate in that the town’s Whau Valley water supply reservoir was not full in March. The reservoir had around a 550 000 cubic metre capacity, and acted as a flood detention dam. Whangarei’s working population was told to go home on the afternoon of 29 March as the water level in the reservoir rose, reaching within 300 mm of the back-up spillway crest. The town became gridlocked with traffic, and, had the water overtopped the floods Northland the on Focus spillway, serious inundation could have occurred. Cars could have been swept away, with potential loss of life. Areas receiving greater than 1-in-10, NIWA was part of a team that reviewed some of the worst- 1-in-50, and 1-in-100 AEP rainfall on affected areas. We concluded that flooding and landslide 28–29 March 2007. damage was worst in places where dwellings or assets had been situated in precarious locations. Many of the damaged sites had experienced similar events before, but people’s memories are short, and increasing population density means that more people are now living in hazardous locations. People in Northland also seem to distrust and ignore heavy rain forecasts, possibly because there have been false alarms in the past. Not again … The estimated cost to individuals, business, and the Far North District Council for the March and July floods is $85 million. On 9–10 July a second extreme rainstorm, caused by Considerable work is now required to improve existing flood similar meteorological conditions, dumped heavy rain protection works, to relocate vulnerable access roads, to over much of Northland, with more than 300 mm falling raise and relocate buildings, and to build retaining walls. around Kaeo. More than 500 people were stranded by Recommendations made by hazard management teams since slips and flooding. Seventy roads were closed and six the two floods include more research into better warning properties were rendered uninhabitable. systems, better hazard maps, and the incorporation of hazard knowledge into regional development plans. A vehicle stranded in rapidly-rising floodwaters during the 2007 Northland weather event. [Photo: Northland CDEM Group].

Natural Hazards 2007 7 8 Hazards summary Natural Hazards 2007 Earthquakes Tsunami Australia), Tasman District Council, Port of Taranaki Ltd., Lyttelton Port of Christchurch. of Port Lyttelton Ltd., Taranaki of Port Council, District Tasman Australia), Meteorology, of (Bureau Centre Tidal National Timaru, PrimePort NIWA, Sources: a 134. On generated earthquake January, 8.2 amagnitude 7.4 3. amagnitude 30September, On adepth at earthquake 8.0 by amagnitude 162. On caused was August, atsunami tsunamis size were: of country. order In these in Zealand New 2007,around in this occurred damage no but level gauges sea by open-coast Four tsunamis recorded were throughout eastern Otago. eastern throughout 10 km deep and centred 20 km southeast of Dunedin, was felt Peninsula. 4.1Coromandel Also amagnitude earthquake, the Aucklandand felt were throughout 4.5. These magnitude of biggest the Orewa, of Gulf Hauraki in the east centred small shallow three included earthquakes Unusual earthquakes 180 felt. were during 2007,intermittently 1200 withabout which of events, 2005, Bay continued Plenty, of central in January which began in the close to Matata region in the activity Seismic swarm 7.3 of magnitudes 6.4 respectively. and Island, with Stewart of southwest km 400 about centred and shallow both were significant these of most two The reported. were region Zealand New the outside located Four earthquakes Te of northwest Anau. km 50 Fiordlandin the region, centred 5.9 magnitude 155 30November, event on also was km-deep, a earthquake, deep largest The damage. minorand to moderate landslidesMilford area, in the Sound Milford of caused Sound On 16 October, a magnitude 6.7 earthquake centred 60 km west 20 on December. Gisborne of southeast km, km 50 40 of adepth at offshore centred earthquake 6.8 magnitude the was earthquake destructive most and largest The forZealand. New year average –an occurred greater website during 2007, and 26 earthquakes of magnitude GeoNet the felt through werereported 5.0 earthquakes 504 of A total or Source: GNS Science GNS Source: 1. Gizo, of 2April, south On from originated atsunami the Chatham Islands and Sumner Head (0.18 Head Sumner Islands and Chatham the m). inat were Zealand New wave measured heights peak The Russia. of coast Kurileast the near tsunami Islands, off Island,Dog Foveaux 3.25 later. around Strait, hours at wave 0.45 of tsunami, heights peak recorded mwere and a Islandsgenerated Auckland the of 10 of northwest km earthquake. the Christchurch, Head, Sumner after 20 hours at wave wave 0.46 of highest m. m)The recorded (0.54 was Islands 14 Chatham the later, hours reached withapeak waves Lima, of first The Peru. south coast the off earthquake to Greymouth area. area. to Greymouth Farewell Cape towards Tasman the and then Coral the Seas, into waves tsunami south zone directs Islands subduction Solomon the of which orientation the models show that midevening. in tide around the This confirmed tsunami Taranaki.Bay Port and waves Fortunately, occurred peak the Jackson at Wave over also mwere 0.5 measured heights NIWA’sat 11.5 gauge Charleston earthquake. the after hours 10 of wave highest The a depth km. 1.10 of measured mwas 8.1 at Islands, result amagnitude of Solomon the earthquake adjacent single-storey buildings, causing single-storey damage. adjacent of buildings roofs the fallen through had two-storey from fewchimneysVery parapets brick places afew In broken. were significant damage. to have not suffered buildings appeared commercial and buildings. houses concrete Most and brick mainly were walls, collapse,cracked these in older partial and windows, shop broken of while that instances were found there 21 travelled who on to Gisborne December staff GNS Science tsunami. a it cause would unlikelythat and be floor sea to the disrupt this of was size this at depth and earthquake an of assessment plate. Pacific The subducting it in the placed earth’s surface, the beneath approximately km at 40 earthquake, the of within by 12 scientists were established minutes. depth The depth and magnitude, location, actual the and earthquake, website withindisplayed GeoNet minuteswas the on the of Shaking information network. seismograph GeoNet’s of instruments by the extensivelyrecorded was earthquake The The year’s worst earthquake –Gisborne, December 2007 earthquake resulted in several partially-collapsed buildings in the central business district of Gisborne city. damaging earthquake in New Zealand since the March 1987 Edgecumbe tremor of magnitude 6.5. The by amagnitude 6.8 earthquake the of coast Gisborne. located 50off km This proved to the most be At 8:55 pmon the evening of 20 December, much Island of the North and South upper Island was shaken • suspended ceilings damaged. ceilings damaged. • suspended plaster and toveneers brick damage of instances • afew fall gables brick and parapets • unbraced walls brick and stone cracked • unreinforced buildings of to fragilecontents damage • substantial floors moves smooth on • furniture in standing experienced alarm,difficulty • general shaking: to match well level MM7 of definition the seemed damage of patterns and people of experience the general In How shaken was Gisborne CBD? or cement-based linings cement-based or

short aftershock sequence ensued. sequence aftershock short only that a was this of location characteristic Luckily another Dunedin. as south far as country the of coast felt east along the efficiently. was Thistravel very explains why earthquake the plate, Pacific seismic the of where waves part into deeper the likely most fault which The extends ruptured earthquake. the which caused stresses plate up. is heating the It these from arising stresses and stress to bending it is subject subducts, this plate As subduction. as known in aprocess 45 mm/year about at region Gisborne the beneath westwards thrust being within plate, Pacific the which occurred is earthquake The and other buildings. other and building, overall relatively houses but damage little to low-rise apartment medium-rise to amodern damage considerable was rise buildings of 4–10 storeys. This helps explain why there medium- which affects frequencies, medium at rich in energy which high-rise affect and low-rise buildings respectively, but relatively deficient in energy at both low and high frequencies, CBD of Gisborne. It indicated that the shaking in Gisborne was asite within from was the important most The earthquake. the More than 100 ground-motion recordings were obtained from Natural Hazards 2007

[Photo: Gisborne Herald] [Photo: Gisborne Herald]

9 Focus on the Gisborne earthquake 10 Hazards summary Natural Hazards 2007 Coastal hazards Wind & tornadoes communications structures. to buildingsvehicles, damage of and incidences numerous and toppled flights, fallen trees, cancelled included Zealand, and New throughout occurred disruption and Damage 100km/h. over gusts of records widespread withnumerous frequent, were northwest and west high the October, In winds from Thames. near totally almost demolished was ashop and phones, land-line poweror without left were people of Thousands recorded. were 150 of windspeeds km/h where Coromandel, the and Auckland, Northland, throughout reported was damage and Auckland, of north offshore reported were 180 of Gusts km/h 10 on declared being July in Northland. emergency of to astate by high winds contributed caused Damage JulyOctober. and in occurring events severe particularly withsome occasions, numerous on (notincluding Windstorms occurred tornadoes) iron in Dargaville. roofing off to atornado, ripped high winds, attributed October 9 22 On June. on trees and felled fences and roofs uplifted Invercargill In Greymouth. of atornado in parts felled trees and roofs off ripped to tornadoes, May high winds,attributed 11 On 21 on also in tornado adamaging Stratford. was March hit firm’s there atrucking tornado damage; causing serious yard 31 on July asmall when affected again was New Plymouth District. Plymouth New in the declared to be emergency Taranakihavoc July, throughout over 4–5 of causing astate wreaked that damagingtornadoes of swarm extraordinary the was year significant wind event the of most The Source: NIWA National Climate Centre Climate NIWA National Source: Waikato. Environment Council, Regional Otago Southland, Environment BOP, Council, Regional Bay Environment Hawkes Christchurch, of Port Lyttelton Council, Regional Northland Council, District Tasman Meteorology), of (Bureau Centre Tidal National Timaru, PrimePort NIWA, Sources: aresult. as destroyed was afactory and Oamaru of part northern along erosion the localised conditions caused storm in Otago, and road, acoastal damaged erosion Southland, In Otago. and in Southland infrastructure and to property damage during JulyStorms Juneand also caused year. the highof highest tides the of withone it coincided surge, but storm This aweak was in 2006. there level reached level 17 on Water Perigean-Spring similar April was peak to the High Mean local mabove level The 0.44 of Westport. near Charleston, at level tide occurred storm measured highest The Peninsula wave Baring buoys. Head and Banks the at waves 2007 of measured largest the alsocaused This cancelled. crossingswere storm with 6mswells. Ferry Strait, in Cook 26 occurred On June, southerlies force gale withsmall tides. coincided this neap storm Fortunately to down 972–980pressures Island. hPa over South much the of 21–23Island on withcentral southeast moved Junethat over South the system low-pressure deep witha coincided m. This 0.45 range in the surge m–0.55 storm registered level gauges sea Charleston, Lyttelton, Head Sumner and Island, Foveaux Dog at 23 tide on Strait June, while predicted 0.65 the mabove 2007 of reached surge storm highest The The Taranaki tornadoes of 4–5 July 2007 On 4–5 July 2007 a swarm of tornadoes cut a 140 km-wide swath of damage across the Taranaki Region. The first tornado hit New Plymouth’s central business district on 4 July, causing damage to a range of structures. Then, on 5 July, over 20 tornadoes occurred throughout Taranaki. The small coastal town of Oakura, southwest of New Plymouth, was worst affected. Two tornadoes ripped through the town, causing major damage to around 50 houses, but fortunately no serious injuries.

A NIWA, GNS Science, and BRANZ (Building Research Association of New Zealand) team spent two days in the area afterwards, collecting data about the tornadoes, and assessing the vulnerability of different types of buildings to such high winds. Scientists made visual observations and detailed measurements of damage, and interviewed eyewitnesses, property owners, and local emergency managers.

The team surveyed damage along four different tornado paths. Wind speed calculations, based on the forces required to bend posts or move heavy objects during the tornados, revealed that the maximum wind speeds in the strongest tornado were around 60–70 metres per second (m/s), or up to 250 km/h. Damage was minor where lower intensity tornadoes had struck, limited mostly to broken windows and lifted roofs. However, the strongest tornadoes caused severe damage, including complete loss of the top storey of a house, loss of roof structure, loss of cladding, and damage to doors and windows. One- or two-storey concrete commercial buildings and single-storey wooden-framed residential dwellings suffered the worst damage. Concrete roof tiles performed well, whereas sheet metal and metal tile roofs did not. Buildings with weatherboard-type cladding were also badly affected, tornadoes Taranaki the on Focus followed by brick veneer and stucco. Houses built after 1980 in general withstood the winds quite well, but older houses incurred more damage. This is not surprising since design standards have improved, especially in the past two decades, although tornadoes are not specifically taken into account in standards and building codes when designing for wind loads. An Oakura house following the 5 July tornado. [Photo: Taranaki Newspapers]

Forecasting tornadoes • Tornadoes are amongst the most intense and destructive winds on Earth. In New Zealand, a tornado will typically last for a few minutes, track across the land for 2–5 km, have a diameter of 20–100 m, and have spinning wind speeds of 32–50 m/s (116–180 km/h). • On average there are about 20 moderate to strong tornado events reported in New Zealand each year. Damage is normally localised and confined to the path of the tornado itself. Tornadoes occur on small spatial scales, have a short life span and a poorly understood initiation mechanism. These features make them extremely difficult to forecast. We do know that particular weather patterns, such as high values of wind helicity and thermodynamic factors, have the potential to generate tornadoes. By international standards, New Zealand’s tornadoes occur at well below accepted thresholds for indicators of potential tornado formation. We are developing techniques to improve our ability to forecast conditions which favour tornadoes, while ensuring the false alarm rate is kept to a minimum. Assumed paths of the Oakura tornadoes. [Background image: LINZ 2007]

Natural Hazards 2007 11 12 Hazards summary Natural Hazards 2007 Snow, hail, &electrical storms Temperature October. October. by lightning, 3 on struck damage, to without was Auckland route on 25 AWellingtonon aircraft September. passenger in Taranaki homes in Levin 5July, on 7000 homes 6000 and in 2June, Rotorua on homes over 1000 lines affected and night 13 of to power damage Lightning March. caused strikes Wellington in the homes over the hours forseveral region 000 40 to about Lightning in power outages resulted strikes to roofs. damage structural some lightning strikes,including to strikes afew power lines, and hailstones 20 were mm in diameter, many were there and in Auckland, Waikato,thunderstorms Waitomo. and Some 25 Island on producing September, overNorth the passed Atrough rain, damage. lightning, withlittle but heavy and 18 on in in Christchurch hail, March resulted Thunderstorms in 2007. damage little to cause Hailstorms appeared occurred. lambs born new- of cm), losses Minor stock closed. schools withseveral (6–8 Canterbury of in Island, low-lying settling parts South the of to low levels east in occurred the snowfall 4September, On road. the in slid off apassenger was she car the when died astudent and abandoned were cars Otago Central Road. In Hill Rimutaka Taupo the 25 on was June, closed as was Road Napier- The also affected. was Road Island’s Desert North the Island high country, South the and and in Otago, Southland, over 20–25 Juneto low levels occurred snowfall worst The in 2007. relatively on fewoccasions occurred snowfall Notable Source: NIWA National Climate Centre Climate NIWA National Source: –2 ºC. reached temperature maximum the where Queenstown, day, Shotover River downthe near floating seen ice was –10 felllow as as temperatures 17 on ºC July. same the On air Dam, where frozen the Idaburn on to play their sport time since able were 2001, first curlers For the Otago Central in 1963.began 8July, the on ºC forJuly lowest since there –8.8 the records following July. recorded over 8–9 frost severe Airport Dunedin Southland and in Otago burst pipes water Many household black ice. treacherous and fog by freezing accompanied often –10.0 7–22 between times at July. were ºC frosts severe The minimum below air recorded temperatures Island locations 13on July 7–22. days between inland South other Numerous in July 1995. fell Minimum –10.0 below air temperatures ºC 18 on Lauder at July, –19.7 since it lowest reached there the ºC –15.4 was year forthe lowest airThe temperature recorded ºC 20–26 November. between regions in many eastern occurred more or 30ºC of conditions temperatures withmaximum warm extremely average, and 5days than more more, about 30°C of or days temperatures during withmaximum March 6 recorded conditions. Alexandra northwesterly dry hot during 22 January on Airport Napier at 33.5 °C recorded in 2007. was year recorded the of temperature highest The 1971–2000 the above were significant normal.No heatwaves 12.7 for2007 was national temperature The average °C, 0.1°C Centre Climate NIWA National Source: 2007 – an expensive year for the insurance industry 2007 was one of the most costly years on record for disaster claims. Weather-related loss events totalled $96.25 million in 2007. On top of that, the costs for the Gisborne earthquake on 20 December are approaching $50 million and still being counted.

The Insurance Council recorded seven separate weather events Summary of the largest weather-related that caused significant property damage where insurance claims of 2007 company combined claims exceeded $1 million for each event. Storm/floods, Far North, 28–29 March 2007 July was a costly month. Most significant was the Upper North • 2569 claims lodged Island 10–12 July storm, which cost insurers $61 million. • Total cost to insurers, $12.5 million This particular storm brought flooding and wind damage, • Residential home and contents claims, $6,350,000 and proved challenging for local authority recovery teams, • Commercial claims, $4,280,000 infrastructure owners, and insurers, as the damage caused • Business interruption/loss of profits, $322,000 • Motor vehicle claims, $900,000 was widespread and variable. Only a week earlier, tornadoes caused significant damage in Taranaki and cost insurers Tornadoes, Taranaki, 4–5 July 2007 $8.3 million, while severe frosts in the second week of July • 1336 claims lodged in Central Otago, South Canterbury, and Southland caused Council Insurance • Total cost to insurers, $8.3 million • Residential home and contents claims, $4,200,000 numerous burst pipe claims totalling $7 million. • Commercial claims, $3,200,000 Weather-related insurance claims appear to be more frequent, • Business interruption/loss of profits, $530,000 • Motor vehicle claims, $216,000 and each year are costing insurers a lot more. The Insurance Council reports that many insurers have experienced reduced Frost, Otago & Canterbury, 7–9 July 2007 profitability in 2007, due to the sheer number of weather- • 2313 claims lodged related claims. • Total cost to insurers, $7.0 million • Residential home and contents claims, $6,000,000 The insurance industry is particularly concerned about the • Commercial claims, $490,000 number of homes and businesses which are situated in flood • Motor vehicle claims, $440,000 plains. The Insurance Council, along with other interest groups, Storm/floods, Far North/Auckland/Coromandel, has been working with the Ministry for the Environment to 10–12 July 2007 develop tools for local authorities to control development in • 18 935 claims lodged flood plain areas. The sustainability of insuring property in • Total cost to insurers, $60.5 million flood-prone areas is a current concern. • Residential home and contents claims, $37,800,000 • Commercial claims, $17,300,000 The Gisborne earthquake on 20 December is the first • Business interruption/loss of profits, $1,000,000 significant earthquake to cause widespread property damage • Motor vehicle claims, $1,300,000 since the Bay of Plenty earthquake in June 1987, which cost High winds, central North and lower South Islands, insurers over $350 million (inflation-adjusted). The Gisborne 23–24 October 2007 earthquake is not likely to approach this level; however, claims • 2277 claims lodged so far are approaching the $50 million mark and may go higher • Total cost to insurers, $4.8 million • Residential home and contents claims, $2,300,000 once rebuilding costings are finalised, likely to be around June • Commercial claims, $1,900,000 2008. • Business interruption/loss of profits, $5000 • Motor vehicle claims, $512,000 Other events with claims totalling over $1 million were the floods in New Plymouth & Nelson on 23 May, and in Hawke’s Bay on 17 July.

Insurance industry payouts for natural hazard events 400 2007 figure Bay of Plenty 350 excludes Gisborne earthquake earthquake 300

250 Wahine storm 200 Manawatu floods $ millions 150 100 50 0 1969 1970 1968 1971 1974 1976 1984 1986 1990 2001 2004 2005 2006 2007 1994 1972 1975 1977 1978 1979 1980 1981 1985 1991 1997 1998 1999 2000 2003 1973 1982 1983 1987 1988 1989 1992 1993 1996 2002 1995 Year

The Insurance Council has maintained an insurance hazard loss register since 1968, when the Wahine sank in Wellington Harbour. Since then, there have been a number of significant losses, the most costly of which include the 1987 Bay of Plenty earthquake ($357 million),

Ice on the Manorburn Dam, July [Photo: 2007. Christchurch Press] the 1999 Queenstown floods ($46.5 million) and the 2004 Manawatu floods, which cost insurers $112 million.

Natural Hazards 2007 13 The Earthquake Commission in 2007 EQC had a busy year in 2007, receiving 6519 claims for natural disaster damage – three times as many as received in 2006 (2167 claims). The Commission is New Zealand’s primary provider of natural disaster

EQC insurance for residential property owners, and continues to provide financial support for many research projects. EQC also funds GeoNet, the national earthquake monitoring and warning system. GeoNet was tested on numerous occasions in 2007 and provided rapid and reliable information for emergency response. EQC & Research 2007 – a busy year for claims EQC is a major funder of natural hazard research in New Earthquakes and landslides were the two main reasons Zealand. Three major new programmes were added to the for claims in 2007, generating 4724 and 1795 claims research activities that we support in 2007: the QuakeTrackers respectively. Once these have all been settled, the schools programme, the ‘It’s Our Fault’ project centred on estimated total cost to the Commission will be around $50 the Wellington fault (see p 21), and a new partnership with million. the University of Auckland to support research on volcanic hazard and risk, geotechnical engineering, and earthquake Three large earthquakes had a major effect on the engineering. number of claims received, with Orewa, near Auckland (495 claims), Milford (1003 claims) and Gisborne (2112 claims) all getting a shake up. Over 5000 claims from QuakeTrackers – back on track the Gisborne earthquake have been received to date, A revitalised QuakeTrackers programme, designed to educate but at least half of these were lodged in 2008, so are not school students about seismology and encourage further study, reflected in the 2007 figures. won EQC support in 2007. The Northland storms and associated floods generated a total of 968 claims, two-thirds as a result of the March event, and the remainder following the July floods. EQC opened a field office in Whangarei to help people after the floods, and field offices were also opened in Invercargill and Gisborne. The Whangarei and Invercargill offices closed in October 2007 and January 2008 respectively, as the majority of claims from each area had been settled. GNS scientist Dr Brad Ilg with students from Upper Hutt High School. [Photo: Kate GNS Whitley, Science]

The programme, first started in 1998, is to be re-established following a recent review and recommendations for a major overhaul. The revised version of the programme will again centre on a network of seismographs in schools, but this time will use a simple, robust, and reliable instrument developed for similar purposes in the USA. (The original programme relied on the relatively expensive and more complex machine available at the time, and this restricted participation.) The goals for the revised QuakeTrackers programme are to: • develop and provide access to educational resources for teachers, students, and others • provide hands-on learning opportunities by means of school- based seismometers • maintain a website where data from the national geophysical monitoring network GeoNet, and other sources, are freely available for use with other teaching materials • encourage widespread participation • ensure the effectiveness of the programme through appropriate New Zealand Qualifications Authority assessments. An advisory board which comprises representatives from the Royal Society of New Zealand, GNS Science, Victoria University, and EQC will oversee the QuakeTrackers programme. We also hope that the New Zealand Geophysical Society, the New Zealand Society for Earthquake Engineering, and the New Zealand Association of Science Educators will be represented on the board in one form or another. The programme will be managed on a day-to-day basis by the Royal Society of New Zealand.

14 Natural Hazards 2007 Guidelines to assist natural hazards planning

Guidelines

NIWA and GNS Science have been involved with the production of a number of natural hazards guidelines and guidance notes in 2007:

From the Ministry for the Environment: • Coastal Hazards & Climate Change – a guidance manual for local government in New Zealand

• Climate Change Effects & Impacts assessment – a guidance manual for local government in New Zealand forthcoming from: http://www.mfe.govt.nz/ publications/

From Quality Planning: • Quality Planning natural hazards guidance note available from: http://www.qp.org.nz/

From GNS Science: • Guidelines for assessing planning policy and consent requirements for landslide-prone land • Planning for development of land on or close to active faults • Pre-event recovery planning for land-use in New Zealand available from: http://www.gns.cri.nz/services/ hazardsplanning/

Natural Hazards 2007 15 700 kilometres per hour: not much slower than a Boeing 737, and the average speed of the August 2007 tsunami as it travelled from Peru to reach the Chatham Islands. Photo: Stefan Reese, NIWA

16 000 000 tonnes of TNT: the equivalent of the 6.8 magnitude earthquake that struck off the coast of

Did you know ... ? ... know you Did Gisborne on 20 December.

680 male African elephants: the weight of the boulder-laden lahar as it stampeded past at 30 km/h in the Whangaehu Gorge on Mt Ruapehu, March 2007. Graphic: Geoffroy Lamarche, NIWA Photo: Christchurch Press

11 000 000 cubic metres: the volume of debris that would fill 370 000 truck- and-trailer units, and the size of the Young River landslide in the Southern Alps, August 2007. Photo: Manville, Vern GNS Science

80 000 000 cubic metres: the amount of water used in a year by 877 000 people on a connected water supply; the same as the estimated volume that flooded the Hikurangi Swamp over four days in the March 2007 Northland floods.

16 Natural Hazards 2007 Photo: Alan Blacklock, NIWA 2–3 centimetres a year: the rate at which

your fingernails grow, and roughly the same rate as New Zealand’s tectonic plates move. Graphic: NIWA

Minus 8 °C to minus 13 °C: the night time temperatures on 10 consecutive days – cold enough to freeze the Idaburn Dam in Central Otago in July 2007 to a safe thickness for a full-scale ‘bonspiel’ curling competition,

the first for six years. ? ... know you Did

70 metres per second (250 km/h): as fast as a V8 supercar on the straight – the likely speed of the fastest winds in the July 2007 tornado in Taranaki. Photo: Taranaki Newspapers

2 metres per second: the speed a good swimmer does in the 50-metre sprint race in the pool, and about the same speed at which a rip current can carry a swimmer seawards ...so your chances of swimming against the current are slim!

80 000 000 cubic metres: the amount of water used in a year by 877 000 people on a connected water supply; the same as the estimated volume that flooded the Hikurangi Swamp over four days in the March 2007 Northland floods.

Natural Hazards 2007 17 Photo: Andy Short, Sydney University Nine hundred civil defence events recorded in 2007 The Ministry of Civil Defence & Emergency Management recorded 900 weather and geological events or emergencies in 2007.

The year has been one of earthquakes, severe weather, tornadoes, floods, a lahar, an eruption, and tsunamis that Exercise Rūaumoko - practising emergency threatened parts of the Pacific, but fortunately did not impact on management response MCDEM New Zealand. The spread of events gives an important message, Putting emergency management response plans into – that disaster prepardness is important wherever we are. practice, in the form of exercises, provides opportunities During 2007 civil defence emergencies were declared four for building relationships, improving organisational times, in Northland, Otago, Taranaki and Gisborne. These understanding, fostering cooperation, and raising emergencies span the country north and south, east and west, hazard-risk awareness. MCDEM is responsible for the and follow a historical pattern. In the past five years there have coordination of all-of-nation emergency management been 14 declarations, 12 because of flooding, which is by far exercises, which involve a large cross-section of voluntary the most common emergency. and professional organisations. These include CDEM Groups, central government departments, emergency Declaration of a state of emergency is a public method of services, lifeline utilities, and science and research granting the appropriate people statutory powers to protect organisations. life and property in events which are beyond the normal emergency response – in other words, events that require In 2007, MCDEM coordinated the preparations for a major elevated levels of coordination and resources. The rationale for emergency response management exercise – Exercise declaring a state of emergency is: Rūaumoko. The exercise is to test readiness for a volcanic eruption in Auckland, with the ‘actual’ eruption scheduled • an emergency event has occurred or may occur for March 2008. • the safety of the public or property is endangered • loss of life, injury or illness or distress may be caused • usual services are inadequate to deal with the emergency. Science and CDEM in partnership A highlight of Exercise Rūaumoko has been the close A MCDEM guideline (available at www.civildefence.govt.nz) involvement of university and research institute scientists explains why declarations of states of emergency should be as partners with CDEM. The Auckland Volcanic Science made, who should make them and how they should be made. Advisory Group (AVSAG) was established to test Clearly, nowhere in New Zealand is hazard-free. The challenge arrangements for provision of science advice in the event is to know what hazards different parts of the country face, to of an emergency. The group comprises physical and know what to do about them, and to be prepared. social science experts from GNS Science, MetService, and Auckland, Waikato, and Massey universities, with liaison 450 representatives from the Auckland CDEM Group and MCDEM. 400

350 Number of recorded warnings and We have seen an improved understanding of the hazard events by type in 2007 operational needs of emergency managers and scientists, 300 and development of better working networks amongst 250 geoscientists and emergency managers. The exercise

200 underscored the vital role that coordinated scientific advice plays in effective emergency response, and has 150

Number of reported events emphasised the importance of the planning process for

100 fostering effective partnerships.

50

0 Heavy rain Earthquake Strong wind Snow Storm tides & Tsunami Volcanic waves Hazard type The Auckland volcanoes. [Photo: Lloyd homer, GNS Science]

18 Natural Hazards 2007 Developing a nationwide flood risk management policy Floods are New Zealand’s most frequent natural hazard, and almost every year communities in New MfE Zealand are affected by flooding. In 2007, the Ministry for the Environment made good progress in work towards new policies which will help reduce the risks associated with floods.

2004 was a particularly bad year. Severe flooding swamped parts of the lower North Island in February, with about 2300 people evacuated and over 2000 farms affected. Then, in July, the Bay of Plenty was hit, with over 3200 people evacuated and 400 farms damaged. Damage to property and disruption to normal life was significant in both cases, and highlighted the problems communities face in a major flood. The 2004 floods prompted the Government to review flood risk management practice. The two-year review started in 2005, and was led by the Ministry for the Environment. Preliminary review findings show that: • there is no standard approach to flood risk management across New Zealand. Councils use a variety of methods and tools to manage flood risk. A clear benefit is that local approaches can be responsive to the local conditions; however, some councils have better resources, including information and funding, to help achieve robust flood risk management.

• good information, including data on local hydrological, Wainui Bay bridge on Wainui Road, near Ngaire. Te [Photo: Northland Regional Counci] topographical, and environmental conditions, is critical to understanding the nature of flood hazards and methods In response to the preliminary review findings, in March 2007 for managing flood risk. Good information is also crucial the Government decided to develop a national policy statement to withstand scrutiny in planning processes that include on flood risk management under the Resource Management developing and implementing plans, and assessing Act. The aim of the statement is to help strengthen the current development proposals. Some councils are having difficulty policy framework by acknowledging the significance of good ‘holding the line’ in planning and policy areas, meaning that flood risk management, and to provide clear direction for flood plains are still being developed. decision makers. A proposed statement should be ready for • many of our larger cities and towns are on flood plains. public consultation in 2008. Communities are often protected by physical works, such A New Zealand Standard is also being developed to help as stopbanks, which work well up to the point they are improve flood risk management practice. The draft standard designed for. Once the design point is reached, emergency went out for public comment in November 2007 and should be management is the most often cited response to deal with finalised by mid 2008. larger than expected floods or failure. Residual risk is not often explicitly managed. More information on the review work programme can be found at: http://www.mfe.govt.nz/issues/land/natural-hazard-mgmt/ flood-risk-review.html. Flooding is the most common reason for declaring a state of local civil defence emergency in New Zealand. In this instance, the Northland floods of July 2007. [Photo: Northland CDEM Group]

Natural Hazards 2007 19 Validating NZLAM, our weather hazards forecasting model 2007 has been an eventful year for weather-related hazards. It has also been a year where we have made important advances in our understanding of some of these events, and in our ability to forecast them. At the core of all our work is the continuing development and validation of NZLAM (the New Zealand Limited Area Model) – NIWA’s unique high resolution weather forecasting model. NZLAM is the first link in the chain of models used to produce high-resolution multi-hazard forecasts for New Zealand and its marine Research

environment.

Forecast Period How accurate are our forecasts? 1−12 hr 37−48 hr As part of our work to monitor NZLAM performance, forecasts Observations from the model are routinely compared against data from 137 15 representative observation sites. A full range of variables are compared including temperature, relative humidity, wind speed and direction, precipitation, cloud amount, and soil moisture. 10 Quantitative Precipitation Forecasts (rainfall forecasts) are perhaps the most difficult forecasts to verify. Rain gauges are notoriously unrepresentative, as precipitation rates can vary

greatly over distances of less than 100 m, and it is also very 5 difficult to model all of the important processes necessary

to forecast rainfall accurately. Our NZLAM results are highly Sum of Convective and Large Scale Rain Amount (mm) encouraging, however. The timing of rain events is generally

well forecast, as are the rain amounts. Similarly, our wind 0

forecasts demonstrate high levels of accuracy, both in terms of Feb 12 Feb 14 Feb 16 Feb 18 forecasting the timing of the passage of fronts, and the force of Direct comparison of NZLAM precipitation forecasts with the the wind. Our results imply that NZLAM forecasts are generally Paraparaumu Airport rain gauge for the storms of February 2004. The accurate out to 48 hours ahead. observed hourly accumulations are shown in black and the forecast ranges in colour. The model’s forecasts closely match what actually happened.

Modelling winds at high resolution – a case study from the lower North Island High winds regularly cause damage and disruption throughout Satellite images showed atmospheric lee waves over the New Zealand. Our capacity to forecast wind accurately at a Wairarapa had a wavelength of about 13 km. NZLAM local level is improving markedly, because, using NZLAM’s predicted these conditions well – the model’s spacing between high resolution capabilities, we can now model the affects that lee-wave ridges was about 14 km, almost exactly matching the landscape has on local wind conditions. observed spacing. When wind travels over a landscape feature, such as the The model also confirmed that the strongest surface winds Tarauas, flows in the lee of the feature are disturbed. During a tend to be on the eastern side of downdrafts, with weaker recent experiment to model winds over the lower North Island, winds east of the updrafts. The strong downslope winds on the we proved that NZLAM can now simulate this lee-wave activity leeward (down-wind) sides of the highest peaks in the Tararuas at high resolution. We nested the model down to 333 m were also evident in the model’s output. The simulation helps horizontal resolution, a much higher resolution than the normal explain why it is so much windier at Martinborough (located 12 km we work at. in green shading in the graph below) than Greytown (yellow shading) under strong northwesterly conditions. On the day we chose to run the experiment – 11 August 2007 – there were strong northwesterlies and stable conditions.

A vertical cross section from NZLAM at 333 m resolution, passing across the Tarauas Greytown Martinborough and the Wairarapa plains. Vertical wind speed is shown by the coloured shading, and the direction of flow by the stream lines.

Tararua range

20 Natural Hazards 2007 Forecasting floods – the importance of riverbed evolution The ultimate purpose of flood forecasting is to reduce property not often used as a planning tool. Also, river bathymetry that damage and save lives. To do this, we need to predict the exists before a flood may not be representative during and after extent and depth of floodwaters that may occur, and this a flood because of the bed and bank erosion and the sediment involves having accurate knowledge of the shape and structure deposition that occur during the flood. (morphology) of riverbeds, as well as how water moves. We are overcoming these factors by linking hydrological and Up until now, flood predictions have been made by providing morphological models to calculate how much sediment a river forecasts of river flows and sea levels to computer models will erode, transport, and deposit, at a range of flows. Ideally which calculate water depths and velocities based on digital such models will eventually predict river widths, depths, and models of ground topography and surface roughness. An evolution, over the years, given data on bed and bank materials Research accurate measurement of topography can be made using LiDAR and the streamflow history. When these models are linked, (airborne laser scanning) but this does not work under water, so through NZLAM, to other forecasts such as rainfall and storm cannot tell us about the riverbed. The expense and complexity surge forecasts, our overall ability to predict floods, and their of bathymetric bed surveys means that hydraulic modelling is extent, will be greatly improved.

An aerial photograph of a bend in the Tongariro River (left), and output of our linked hydraulic- morphologic model (right), showing scouring of the riverbed. Comparison of the two images shows that the model is generating an accurate estimate of the riverbed structure. The model has used historic river flows and bed sediment characteristics to . calculate natural river bed elevations. (Photo: Google Earth)

River flow forecasting: validating our models

NIWA’s river flow forecasting system is now Flow Prediction at Murupara (Pumice): Old Calibration Method operational and providing real-time flood warning 300 information for the Rangitaiki River in the Bay of 250 Parameter uncertainty Plenty. Measured data 200 Best modelled data s / 3 ^

The Rangitaiki is a difficult area because it has split m 150 – w

geology: the western half is pumice, which soaks up o l rainwater and responds slowly to rainfall; the eastern F 100 half is greywacke, where water quickly runs into the 50 river and produces high flood peaks. We are using 0 flow gauges in different parts of the catchment to 0 1000 2000 3000 4000 5000 6000 7000 8000 validate our models and test new model calibration Time - strategies. These new methods use geological Flow Prediction at Murupara (Pumice): New Calibration Method mapping to classify the river basin into different 120 hydrological clusters, and simultaneously estimate 100 river flow for each cluster type. The aim is to Parameter uncertainty Measured data

/ s 80

achieve a model which accurately predicts river ^ 3 Best modelled data

m 60 flow in different locations, based on our knowledge – w o of hydrological processes and geological variations, l 40 F and we are making good progress to this end. 20

0 0 1000 2000 3000 4000 5000 6000 7000 8000 Programme name: Reducing the impact of weather- Time - related hazards Leader: NIWA Model performance for a pumice catchment: Old calibration method (top) Duration: 2004–08 without geological information overestimates flows; new calibration method Funders: Foundation for Research, Science, & Technology (bottom) uses geological mapping to improve simulation of reduced flood peaks Contact: Michael Uddstrom, [email protected] in pumice catchments, producing more accurate forecasts.

Natural Hazards 2007 21 Geological hazards and society

Natural hazards research at GNS Science, and its application to New Zealand society, has continued in a wide variety of areas. Exemplified in this review is the fundamental work on the earthquake hazard model for New Zealand, the development of tsunami evacuation protocols, and the ‘It’s Our Fault’ applied research on earthquake risk in Wellington. Other 2007 highlights included obtaining new understanding of the volcanic risk in Auckland, small lahars on Mt Ruapehu, earthquakes in Gisborne and Fiordland, large rock avalanches in the Southern Alps, and generally slow-moving landslides affecting central North Island towns

Research and infrastructure. Preparing New Zealand for tsunami Evacuation maps contain instructions for responding to natural, informal, and official warning signals. Maps use three zones: GNS Science has been conducting tsunami risk reduction • a red foreshore coastal exclusion zone that can be referred to research for the last decade. Following the Indian Ocean if only a small tsunami is expected tsunami in late 2004, intense public and political interest has fostered a desire to be more prepared for tsunami affecting • an orange zone that intends to cover most distant-source New Zealand. Research has included a range of comparative tsunami and be used in official evacuations studies and social science surveys, and findings from this • a yellow zone that allows for the very infrequent but larger research are being applied in collaborative emergency local and regional sources that may give larger tsunami. management projects such as the all-hazard warning notification options for Auckland and Gisborne regions, The region and pilot community together have agreed that they Auckland evacuation planning, Auckland tsunami contingency want to set up a system of maps, signs, plans, and exercises plan, and a review of the signs used to warn and guide people now, and move the lines as science improves. The focus is on in the event of a tsunami. having a robust methodology within which zones can change if needed over time, but the number of zones, style of maps, The signs review was part of a MCDEM project that has plans, and signs don’t need to be significantly redesigned. recommended, as high priority, linked evacuation zone signs, evacuation map information boards, and evacuation route

signs. EVACUATION ZONES

Red Shore Exclusion Zone Evacuate for any possible tsunami

Orange Evacuation Zone Orange " Evacuate when officially directed to Tsunami evacuation planning with Yellow Evacuation Zone Yellow Consider evacuating on any natural or unofficial warning "

LEGEND

local communities " Building " Road We have been working with Northland and Wellington " " River Safe Zone " Evacuation Safe Regions to apply research in developing tsunami evacuation " Location " " " M Marae " " " planning. The goal is to develop a system that is community- " " "" Emergency Centre " " " E Walking Bridge based and uses integrated written planning, evacuation maps, (do not use in evac.) " S School " signs and exercises. Walking evacuation route

A pilot project is underway in Whananaki, a coastal " " "

" " " community in Northland. Community representatives met with " " the local CDEM manager, district emergency management " and GNS Science staff. Materials and options for evacuation " "

"

planning were presented and discussed, then the process was " " " " " " " " " " " " turned over to the community to modify to suit their needs. " " " " " " " " M " " " " " " " The group came up with an 11-step process for establishing " " " " " " "

" " " E tsunami signs and evacuation maps within a region, district, " " " " " " " " " "

" " " " " " " city, or community. The process also includes annual exercises " " " and a review of zones and maps every few years. S" "

" " " " " " " " " " " " " " " " " " Whananaki have now " " " " " " "

"

" reached the fifth step in "" this process – walking

" through draft evacuation " " " " "

" routes and sign locations " DRAFT TSUNAMI " " " " " on the ground – with " "

EVACUATION ZONES " TSUNAMI a plan to finalise Community revision v1; 9 Nov 2007 "

" " " " evacuation maps within Full map is annotated with " EVACUATION evacuation directions and the next few months and tsunami facts boxes

"

" " ROUTE obtain and place signs " within the next year or so. The ownership of the project now resides with the community, in cooperation with local and regional emergency Programme name: Geological Hazards & Society Leader: GNS Science managers. Hopefully, as other Northland and Wellington Duration: 2004–08 communities roll out a similar process, people from pilot Funders: Foundation for Research, Science, & Technology areas can come and present their own experience to the new Contact: Kelvin Berryman, [email protected] communities.

22 Natural Hazards 2007 It’s Our Fault: better defining the earthquake risk in Wellington ‘It’s Our Fault’ is a seven-year, $3.5 million project being The research aims to determine: undertaken by GNS Science and collaborators, with the aim of • the likelihood and frequency of large earthquakes better defining Wellington’s earthquake risk. The Wellington • the expected size of earthquakes region has four major active faults and a number of second- • their physical effects order faults, including some in Cook Strait. All of these are • their social and economic impacts. capable of producing a large and damaging earthquake. Current geological investigations include trenching several The project will improve knowledge of the individual faults, faults, allowing the earthquake history for a given fault to be and also the way they interact with each other. A large determined, and providing data that can be used in a statistical earthquake on one fault may advance or retard earthquakes analysis of the likelihood of the next earthquake on that fault. Research on neighbouring faults, but the extent of this effect is not well A detailed analysis of how Wellington region faults interact, understood at present. Preliminary studies show that the 1855 validated with the new geological data, should be able to Wairarapa earthquake should have de-stressed a large part of convincingly demonstrate that current Wellington risk is lower the Wellington fault, thus delaying the next large earthquake. than the long-term average, by providing reliable conditional probabilities to replace those currently based on random occurrence. The project is structured so that interim results from each of the four components can be reported on annually. This will ensure that there is prompt uptake of the results and returns for the research effort, particularly in the area of insurance. The project will help Wellington become better prepared for, and safer from, earthquakes by enabling better decision making to protect assets and reduce potential casualties.

Programme name: It’s Our Fault Leader: GNS Science Duration: 2006 –12 Funders: EQC, ACC and Wellington City Council Contact: Hannah Brackley, [email protected] GNS scientists in work at a trench revealing the Ohariu Fault, Wellington [Photo: Hannah Brackley]

Updating the national seismic hazard model for New Zealand A team of earthquake geologists, seismologists, and engineering seismologists at GNS Science, in association with NIWA, are making good progress in updating the national probabilistic seismic hazard (PSH) model for New Zealand. The new model will supersede the older national model completed in 2000. The model incorporates around 100 new offshore fault sources, and utilises new New Zealand-based equations for estimating the earthquake sizes and recurrence intervals for the faults. The seismicity catalogue Old versus new levels of peak ground acceleration (in units of g; 1 g being equal to 9.8 m/s2) expected with input to the model has also a 475-year return period on average ground conditions. The 475-year return period is equivalent to a 10% been updated to include post- probability of exceedance in 50 years, the measure of hazard commonly used in engineering and planning 1997 seismicity data, and studies. The most obvious differences between the maps are that the estimates of hazard have decreased at improved methodology for the the junction of major faults in the West Coast (e.g. Alpine and Hope Faults; the black area on the left hand treatment of the seismicity. map), and there have been overall reductions to the estimated hazard in the centre and north of the map area. Preliminary PSH maps produced from the completed South Island section of the new model show a similar pattern of hazard to the older maps at the national scale, but some significant reductions in hazard at the regional Programme name: Geological Hazards & Society scale. These reductions reflect a rationalisation of fault Leader: GNS Science segments in the onshore areas (i.e. lengthening and Duration: 2004–08 Funders: Foundation for Research, Science & Technology linking of some fault sources in the new model), and the Contact: Kelvin Berryman, [email protected] influence of the new seismicity catalogue model.

Natural Hazards 2007 23 The Regional RiskScape Model

RiskScape is a tool being developed jointly by GNS Science and NIWA, which can simulate regional natural hazards, and produce estimates of damage in dollars and likely casualties. It will provide support for decision makers such as land-use planners, design engineers, emergency managers, and insurance assessors.

Considerable progress continues with RiskScape software and • inventory databases that describe the location and development of the various modules that convert a potential engineering attributes of critical infrastructure vulnerable to

Research natural hazard into possible consequences for communities in volcanic impacts terms of damage, disruption, and casualties. The three local • spatial analysis techniques used to assign the intensity of the authority partners we are working with, based in Christchurch, volcanic hazard to the infrastructure according to location Westport and central Hawke’s Bay areas, have provided • fragility (or vulnerability) functions that relate volcanic hazard valuable feedback. We have improved the operation and the intensity to expected damage ratios for each type of volcanic look and feel of the RiskScape system, including developing hazard and inventory type. a more flexible connectivity with the GIS systems that local authorities routinely use. Testing of RiskScape Volcano was based on the Okataina Volcanic Centre in Rotorua District. Potential consequences for people, agriculture, forestry, and infrastructure were compared RiskScape Volcano – modelling between tephra (ash-fall) impacts and those resulting from a volcanic hazard risks lava-dome collapse, which would produce a pyroclastic flow. A PhD student, Grant Kaye (University of Canterbury), The key finding was that tephra presents a much greater risk has been working with the team to expand the capacity of to all the various sectors tested than pyroclastic flows. This RiskScape to simulate a complete suite of outcomes to volcanic is because tephra-related hazards would be widespread hazards. This expanded module is called RiskScape Volcano. compared to the relatively small and localised footprint of the RiskScape Volcano has the following features: more damaging pyroclastic flow. • various models that each mimic different expressions of Ultimately, RiskScape Volcano will be capable of assessing risk volcanic hazards, such as ash-fall (tephra), rapid downhill from multiple types of volcanic hazards in any location, such flows of hot gas, rocks, and tephra (pyroclastic flows), and as the risk to infrastructure from lava flows in a reawakened lava flows Auckland volcanic field.

Estimated damage ratios (Dr – the cost of repair or damage relative to replacement cost, as a percentage) to exotic forests from tephra (ash-fall) in the Rotorua District from a volcanic eruption scenario in the Okataina Volcanic Centre.

24 Natural Hazards 2007 The risk to buildings from wind and tornadoes Estimating wind or tornado damage to buildings requires following the July 2007 tornado event in Taranaki (see p.11) and simulation of wind gusts hitting critical elements of individual will feed into improved wind fragility curves for New Zealand structures. To do this, wind information at a very high spatial weather conditions and housing stock. resolution is needed, plus a reliable specification of the wind- 100 sensitive attributes of structures. Timber – pre 1940 Timber – post 1960 80 Computer models can provide us with data on wind-gust Timber – 1940/60 exposure over an entire urban or rural area. We are working Tornado damage - timber/weatherboard - post 1960 buildings with a sophisticated model called BLASIUS (Boundary Layer 60 Above Stationary Inhomogeneous Uneven Surfaces). BLASIUS models the wind-gust speeds for extreme events up to average Research 40 return interval (ARI) periods of 1000 years for Christchurch,

Hawke’s Bay and Westport, with model runs in RiskScape damage ratio (%) simulated on a grid of 100x100 m cells representing the land 20 topography. 0 The other approach in estimating wind damage is to match the 0 10 20 30 40 50 60 70 80 90 strength of different elements of a building to their vulnerability -20 to the wind gusts they are likely to be exposed to. Work wind speed (m/s) continues on developing wind fragility curves for different The level of damage caused by the Taranaki tornadoes in relation to types of buildings, in collaboration with Geoscience Australia the estimated wind speeds for timber/weatherboard type buildings and the Cyclone Testing Station, James Cook University, built after 1960, plotted onto existing wind fragility curves used within Townsville. Valuable damage information was also collected the RiskScape system. Despite the variations in the level of damage, the fragility curves represent the Taranaki tornado damage well.

Java tsunami surveys improve damage predictions New Zealand has not experienced a damaging tsunami in Traditional unreinforced brick buildings were essentially the 46 years since ‘the Chile event’ (May 1960). This is good destroyed at an inundation depth of 3 m; while minimal news for coastal communities, but means there is a lack of reinforced-concrete columns reduced the damage levels information on how well our buildings and infrastructure would significantly. Multi-storey buildings with substantial reinforced stand up to a moderate-to-severe tsunami; information we concrete frames suffered relatively low levels of structural need to fine-tune the tsunami fragility functions in RiskScape damage. Buildings shielded by any obstacles or other houses for assessing potential tsunami damage for New Zealand also sustained substantially less damage – up to 2–5 times communities. lower than buildings exposed directly to the tsunami. Rates of death and serious injury were both about 10% of those people The tsunami that hit Java in July 2006, which had a moderate caught in water depths of 3–4 m. 3–5 m wave height, gave the RiskScape team the opportunity to collect valuable data on matching tsunami inundation This type of information has now been incorporated into depths to casualty rates and building-damage levels. The team RiskScape, and we continue to make improvements to the surveyed ground profiles, inundation depths, and damage quality of the base data on which the model simulates different along several transects from the coastline into the hinterland. hazard scenarios. The degree of damage observed was diverse, and was primarily dependent on tsunami water depth and the building construction type. Damage ratios were derived from subjective estimates of the proportion of damage to the main structural elements of the damaged buildings: the foundations, floor, walls, roof and ceiling, fittings, and services.

Programme name: The Regional RiskScape Model Lead organisation: NIWA and GNS Science (50:50 joint venture) Duration: 2004–08 Funder: Foundation for Research, Science, & Technology www.riskscape.org.nz Tsunami damage in Cikembulan Village (approximately 5 west of Pangandaran. km Photo: Jim Cousins, GNS Science.

Natural Hazards 2007 25 Selected hazard research publications 2007

Alloway, B.V.; Lowe, D.J.; Barrell, D.J.A.; Newnham, R.M.; Ellis, S.M.; Wilson, C.J.N.; Bannister, S.C.; Bibby, H.M.; Heise, Almond, P.C.; Augustinus, P.C.; Bertler, N.A.N.; Carter, L.; W.; Wallace, L.M.; Patterson, N. (2007). A future magma Litchfield, N.J.; McGlone, M.S.; Shulmeister, J.; Vandergoes, inflation event under the rhyolitic Taupo volcano, New Zealand: M.J.; Williams, P.W. (2007). Towards a climate event numerical models based on constraints from geochemical, stratigraphy for New Zealand over the past 30,000 years (NZ- geological, and geophysical data. Journal of Volcanology INTIMATE project). Journal of Quaternary Science 22(1): 9–35. and Geothermal Research 168(1-4): 1–27; doi:10.1016/j. jvolgeores.2007.06.004 . Anon (2007). Eight thousand years of storms and droughts. Water & Atmosphere 15(2): 24–25. Goff, J.; Walters, R. (2007). Revealing the unseen threat: tsunami sources in the Bay of Plenty. Water & Atmosphere Bannister, S.C.; Reyners, M.E.; Stuart, G.; Savage, M. (2007). 15(3): 22–23. Imaging the Hikurangi subduction zone, New Zealand, using teleseismic receiver functions: crustal fluids above the forearc Gomez, B.; Carter, L.; Trustrum, N.A. (2007). A 2400 yr record mantle wedge. Geophysical Journal International 169(2): 602– of natural events and anthropogenic impacts in intercorrelated 616; doi: 10.1111/j.1365-246X.2007.03345.x . terrestrial and marine sediment cores : Waipaoa sedimentary system, New Zealand. Geological Society of America Bulletin Barnes, P.; Lamarche, G. (2007). Revealing the unseen threat: 119(11/12): 1415–1432; doi: 10.1130/B25996.1. on the lookout for tectonic faults and underwater landslides. Water & Atmosphere 15(3): 20–21. Gravley, D.M.; Wilson, C.J.N.; Leonard, G.S.; Cole, J.W. (2007). Double trouble: paired ignimbrite eruptions and Becker, J.S.; Saunders, W.S.A. (2007). Enhancing sustainability collateral subsidence in the Taupo Volcanic Zone, New through pre-event recovery planning. Planning Quarterly 164: Zealand. Geological Society of America Bulletin 119(1/2): 14–18. 18–30; doi: 10.1130/B25924.1 .

Becker, J.S.; Johnston, D.M.; Paton, D.; Hancox, G.T.; Davies, Gregg, C.E.; Houghton, B.F.; Paton, D.; Johnston, D.M.; T.R.; McSaveney, M.J.; Manville, V.R. (2007). Response to Swanson, D.A.; Yanagi, B.S. (2007). Tsunami warnings: landslide dam failure emergencies: issues resulting from the understanding in Hawaii. Natural Hazards 40(1): 71–87; doi: Hazard research publications research Hazard October 1999 Mount Adams landslide and dam-break flood in 10.1007/sl 1069-006-0005-y. the Poerua River, Westland, New Zealand. Natural Hazards Heise, W.; Bibby, H.M.; Caldwell, T.G.; Bannister, S.C.; Review 8(2): 35–42. Ogawa, Y.; Takakura, S.; Uchida, T. (2007). Melt distribution Bell, R.; Gorman, R. (2007). Finding safe harbour: coastal beneath a young continental rift: the Taupo Volcanic Zone, hazards - rising problems. Water & Atmosphere. 15(3): 16–17. New Zealand. Geophysical Research Letters 34(14): L14313, doi:10.1029/2007GL029629. Christenson, B.W.; Werner, C.; Reyes, A.G.; Sherburn, S.; Scott, B.J.; Miller, C.A.; Rosenberg, M.D.; Hurst, A.W.; Britten, K. Hendrikx, J. (2007). The June 2006 Canterbury snowstorm. (2007). Hazards from hydrothermally sealed volcanic conduits. Journal of Hydrology New Zealand 46(1): 33–49. Eos 88(5): 53–55. Hume, T.; Blackett, P.; Dahm, J. (2007). Involving communities in coastal hazard mitigation. Water & Atmosphere. 15(3): 18. Clark, M.; Woods, R.; Ibbitt, R. (2007). Weathering the storm: flood forecasts for New Zealand communities. Water & Johnston, D.M.; Becker, J.S.; Gregg, C.; Houghton, B.F.; Paton, Atmosphere 15(3): 14–15. D.; Leonard, G.S.; Garside, R. (2007). Developing warning and disaster response capacity in the tourism sector in coastal Cochran, U.A.; Hannah, M.; Harper, M.; Van Dissen, R.J.; Washington, USA. Disaster Prevention and Management 16(2): Berryman, K.R.; Begg, J.G. (2007). Detection of large, 210–216. Holocene earthquakes using diatom analysis of coastal sedimentary sequences, Wellington, New Zealand. Quaternary Jongens, R.; Gibb, J.; Alloway, B.V. (2007). A new hazard Science Reviews 26(7/8): 1129–1147; doi:10.1016/j. zonation methodology applied to residentially developed sea- quascirev.2007.01.008. cliffs with very low erosion rates, East Coast Bays, Auckland, New Zealand. Natural Hazards 40(1): 223–244; Doi: 10.1007/ Coulthard, T.J.; Hicks, D.M.; Van De Wiel, M.J. (2007). s11069-006-0019-5. Cellular modelling of river catchments and reaches: Advantages, limitations and prospects. Geomorphology Kennedy, D.M.; Dickson, M.E. (2007). Cliffed Coasts of New 90(3–4): 192–207. Zealand: Perspectives and Future Directions. Journal of the Royal Society of New Zealand 37(2): 41–57. Davies, T.R.; Manville, V.R.; Kunz, M.; Donadini, L. (2007). Modeling landslide dambreak flood magnitudes: case study. King, D.N.T.; Goff, J.; Skipper, A. (2007). Maori Environmental Journal of Hydraulic Engineering 133(7): 713–720. Knowledge and natural hazards in Aotearoa-New Zealand. Journal of the Royal Society of New Zealand 37(2): 59–73.

Dellow, G.D.; Ali, Q.; Ali, S.M.; Hussain, S.; Khazai, B.; Nisar, Koike, M.; Liley, B. (2007). Measurements of reactive nitrogen A. (2007). Preliminary reconnaissance report for the Kashmir produced by tropical thunderstorms during BIBLE-C. Journal of earthquake of 8 October 2005. Bulletin of the New Zealand Geophysical Research D 112, D18304. Society for Earthquake Engineering 40(1): 18–24. Langridge, R.M.; Berryman, K.R.; Van Dissen, R.J. (2007). Elliott, A.H.; Trowsdale, S.A. (2007). A review of models Late Holocene paleoseismicity of the Pahiatua section of the for low impact urban stormwater drainage. Environmental Wellington Fault, New Zealand. New Zealand Journal of Modelling and Software 22(3): 394–405. Geology and Geophysics 50(3): 205–226.

26 Natural Hazards 2007 Leonard, G.; Wright, I. (2007). Living on the ring of fire. In: Life Reyners, M.E.; Bannister, S.C. (2007). Earthquakes triggered on the edge : New Zealand’s natural hazards and disasters, pp. by slow slip at the plate interface in the Hikurangi subduction 76-115. David Bateman, Auckland, N.Z., Graham Leonard [et zone, New Zealand. Geophysical Research Letters 34(14): al.]. Auckland, N.Z. : David Bateman, Contains material drawn L14305, doi:10.1029/2007GL030511. from the second theme of Te Ara: the Encyclopedia of New Zealand: “Earth, Sea and Sky”. Reyners, M.E.; Eberhart-Phillips, D.; Stuart, G. (2007). The role of fluids in lower-crustal earthquakes near continental rifts. Litchfield, N.J. (2007). Using fluvial terraces to determine Nature 446(7139): 1075–1078; doi:10.1038/nature05743. Holocene coastal erosion and Late Pleistocene uplift rates: an example from northwestern Hawkes Bay, New Rhoades, D.A. (2007). Application of the EEPAS model to Zealand. Geomorphology) (in press) doi: 10.1016/j. forecasting earthquakes of moderate magnitude in southern geomorph.2007.12.001. California. Seismological Research Letters 78(1): 110–115.

Litchfield, N.J.; Van Dissen, R.J.; Nicol, A. (2007). Reassessment Sansom, J.; Renwick, J.A. (2007). Climate change scenarios of slip rate and implications for surface rupture hazard of the for New Zealand rainfall. Journal of Applied Meteorology and Martinborough Fault, south Wairarapa, New Zealand. New Climatology 46(5): 573–590. Zealand Journal of Geology and Geophysics 50(3): 239–243. Saunders, W.S.A.; Forsyth, P.J.; Johnston, D.M.; Becker, J.S. McCaffrey, R. (2007). The next great earthquake. Science (2007) Strengthening linkages between land-use planning and 315(5819): 1675–1676. emergency management in New Zealand. Australian Journal of Emergency Management 22(1): 36–43. McFadgen, B.G.; Goff, J.R. (2007). Tsunamis in the New Zealand archaeological record. Sedimentary Geology Schmidt, J.; Turek, G.; Clark, M.P.; Uddstrom, M.J. (2007). 200(3–4): 263–274. Real-time forecasting of shallow, rainfall-triggered landslides in New Zealand. Geophysical Research Abstracts 9(05778) [2]. McGinty, P.J.; Robinson, R. (2007). The 2003 Mw 7.2 Fiordland subduction earthquake, New Zealand : aftershock distribution, Schorlemmer, D.; Gerstenberger, M.C.; Wiemer, S.; Jackson, main shock fault plane and static stress changes on the D.D.; Rhoades, D.A. (2007). Earthquake likelihood model overlying Alpine Fault. Geophysical Journal International testing. Seismological Research Letters 78(1): 17–29. 169(2): 579–592; doi: 10.1111/j.1365-246X.2007.03336.x. Sherburn, S.; Scott, B.J.; Olsen, J.; Miller, C.A. (2007). McKerchar, A.; Smart, G. (2007). Weathering the storm: planning Monitoring seismic precursors to an eruption from the publications research Hazard to avoid flood damage. Water and Atmospher 15(3): 12–13. Auckland Volcanic Field. New Zealand Journal of Geology and Manville, V.R.; Cronin, S.J. (2007). Breakout lahar from New Geophysics 50(1): 1–11. Zealand’s crater lake. Eos 88(43): 441–442. Smart G.M., Habersack, H.M. (2007). Pressure fluctuations and Nicol, A.; Wallace, L.M. (2007). Temporal stability of gravel entrainment in rivers. Journal of Hydrological Research deformation rates: comparison of geological and geodetic 45(5): 661–673. observations, Hikurangi subduction margin, New Zealand. Stephenson, W.R. (2007). Visualisation of resonant basin Earth and Planetary Science Letters 258(3/4): 397–413; doi: response at the Parkway array, New Zealand. Soil Dynamics 10.1016/j.epsl.2007.03.039 and Earthquake Engineering 27(5): 487–496; doi:10.1016/j. Nichol, S.L. (2007). Lagoon subsidence and tsunami on the soildyn.2006.11.004. west coast of New Zealand. Sedimentary Geology 200(3-4): Uddstrom, M.; Oliver, H.; Andrews, P.; Moore, S.; Sherlock, 248–262. V. (2007). Weathering the storm: from weather prediction to Nichol, S.L.; Goff, J.R. (2007). Holocene record of gradual, forecasting hazards. Water & Atmosphere 15(3): 10–11. catastrophic, and human-Influenced sedimentation from a backbarrier wetland, northern New Zealand. Journal of Coastal Villamor, P.; Van Dissen, R.J.; Alloway, B.V.; Palmer, A.S.; Research 23 (May 2007). Litchfield, N.J. (2007). The Rangipo Fault, Taupo rift, New Zealand : an example of temporal slip-rate and single-event Nott, J.; Neil, H. (2007). Greater frequency variability of displacement variability in a volcanic environment. Geological landfalling tropical cyclones at centennial compared to Society of America Bulletin 119(5/6): 529–547; doi: 10.1130/ seasonal and decadal scales. Earth and Planetary Science B26000.1. Letters 255(3–4): 367­–372. Wallace, L.M.; Beavan, R.J.; McCaffrey, R.; Berryman, K.R.; Orpin, A.; Northcote, L.; Page, M.J.; Trustrum, N.A.; Brackley, Denys, P. (2007). Balancing the plate motion budget in H.L.; Cochran, U.A.; Mildenhall, D.C.; Carter, L.; Gomez, B.; the South Island, New Zealand using GPS, geological and Palmer, A. (2007). Eight thousand years of storms and droughts. seismological data. Geophysical Journal International 168(1): Water & Atmosphere 15(2): 24–25. 332–352; doi:10.1111/j.1365–246X.2006.03183.x.

Power, W.L.; Downes, G.L.; Stirling, M.W. (2007). Estimation Wilson, K.J.; Berryman, K.R.; Cochran, U.A.; Little, T. (2007). of tsunami hazard in New Zealand due to South American Holocene coastal evolution and uplift mechanisms of the earthquakes. Pure and Applied Geophysics 164(2/3): 547–564; northeastern Raukumara Peninsula, North Island, New doi: 10.1007/s00024-006-0166-3 Zealand. Quaternary Science Reviews 26(7/8): 1106–1128; Reese, S.; Bell, R.; King, A. (2007). Under the umbrella: doi:10.1016/j.quascirev.2007.01.005. RiskScape: a new tool for comparing risk from natural hazards. Zhao, J.X.; Zhang, J. (2007). Inelastic demand spectra Water & Atmosphere 15(3): 24–25. of bi-linear models for capacity spectrum method and Reese, S.; Cousins, W.J.; Power, W.L.; Palmer, N.G.; response of simple structures under near-source records. Tejakusuma, I.G.; Nugrahadi, S. (2007). Tsunami vulnerability Journal of Earthquake Engineering 11(4): 631–652; doi: of buildings and people in South Java – Field observations after 10.1080/13632460601149813. the July 2006 Java tsunami. Natural Hazards and Earth System Science 7(5): 573–589.

Natural Hazards 2007 27 Selected hazard studies 2007

National/multi-regional Central North Island Goff, J.R.; Hicks, D.M.; Hurren, H. (2007). Tsunami Berryman, K.R.; McVerry, G.H. (2007). Assessment of fault geomorphology in New Zealand: a new method for exploring location and earthquake design spectra at Parekarangi site, the evidence of past tsunamis. NIWA Technical Report 128. 69 p. State Highway 30, Rotorua. GNS Science consultancy report (Also issued as CDROM). 2007/13LR. 14 p. Hancox, G.T.; Dellow, G.D.; Massey, C.; Perrin, N.D. (2007). Cole-Baker, J.; Britten, K.; Graham, D.J. (2007). Rotorua Reconnaissance studies of landslides caused by the July- Museum soil gas and ground temperature survey. GNS Science October 2006 rainstorms in southern North Island, New consultancy report 2007/166LR. 9 p. Zealand. Lower Hutt: GNS Science. GNS Science report Cousins, W.J.; Smith, W.D.; Johnston, D.M. (2007). Earthquake 2006/26. 37 p. and volcanic risks to assets of the Taupo District Council. GNS Smith, W.D.; Cousins, W.J. (2007). LAPP Fund. Earthquake risk Science consultancy report 2007/80. iv, 45 p., figs, maps. to Councils’ assets in Wellington and Christchurch : update Manville, V.R.; Carrivick, J.L. (2007). Ruapehu crater lake lahar: (2007). GNS Science consultancy report 200/119. v, 54p. bund hydrograph prediction. GNS Science consultancy report Hazard studies Hazard Smith, W.D.; Cousins, W.J.; Wilson, T.M.; King, A.B. (2007). 2007/26. ii, 8 p. Fonterra, seismic and volcanic risk assessment. GNS Science Scott, B.J. (2007). Whakarewarewa village bridges: an consultancy report 2007/68. iv, 82 p., figs, maps. overview of site conditions. GNS Science consultancy report Turner, R.; Burgess, S.; Reid, S. (2007). Meteorological report 2007/311LR. 11 p. on extreme wind events from 1 April 2006 to 31 March Scott, B.J.; Reeves, R.R. (2007). Mokai Crater inspection 13 2007 impacting on the Vector network, NIWA Client Report September 2007, immediate response comments. GNS Science WLG2007–33: Prepared for Vector Networks Ltd. 27 p. consultancy report 2007/282LR. 6 p. Zhao, J.X.; Zhang, J.; Fisher, J.; Somerville, P. (2007). Bounds Sherburn, S. (2007). Analysis of data from the Poihipi Power on the distribution of amplitudes in ground motion prediction Station seismograph: 01 January 2006 to 31 December 2006. results. GNS Science consultancy report 2007/98. iii, 21 p. GNS Science consultancy report 2007/04. ii, 11 p., fig, map. Villamor, P. (2007). TAU-GNS-5 Tauhara geothermal Northland development - known seismic faults. GNS Science consultancy King, A.B.; McVerry, G.H.; Jury, R. (2007). Recommended report 2007/279LR. 3 p. response to NZS 1170.5 public comments on seismicity factors in low-seismicity regions. GNS Science consultancy report Villamor, P.; Wilson, K.J. (2007). Active fault mapping at 2007/174. 15 p. Mapara Valley, Taupo district. GNS Science consultancy report 2007/289LR. 5 p. Salinger, J.; Thompson, C.; Mullan, B. (2007). Rainfall intensity in Manukau City. NIWA Client Report AKL2007–079. 77 p. Waikato Smart, G.M. (2007). The Northland Floods 28-29 March (2007) Wilson, K.J.; Berryman, K.R.; Maslen, G.A.; Read, S.A.L.; Hydrologic Hazards Hindvestigation. NIWA Client Report Wood, R.A. (2007). Aratiatia Fault assessment stage 1. GNS CHC2007–049, FRST C01X0401 (RIWRH). Science consultancy report 2007/306. 24 p. Uma, S.R.; Cousins, W.J.; King, A.B.; Smith, W.D. (2007). Bay of Plenty Recommended damage ratios for property of the New Zealand Jolly, G.; Scott, B.J.; Smith, W.D. (2007). Quantitative Refining Company. GNS Science consultancy report 2007/353. assessment of volcanic risk for activities on White Island. GNS ii, 21 p. Science consultancy report 2007/48. iii, 7 p. Coromandel Reeves, R.R.; Webb, S.; Scott, B.J. (2007). Re: 2005 thermal Becker, J.S.; Stewart, C.; Coomer, M.A.; Hume, T.; Blackett. P.; infrared survey of White Island. GNS Science consultancy Davies, A. (2007). Managing our coast : the tabulated results of report 2007/192LR. 6 p. two community surveys undertaken at Tairua and Waihi Beach. Lower Hutt: GNS Science. GNS Science report 2007/28. 235 p. Gisborne Leonard, G.S.; Saunders, W.S.A.; Johnston, D.M. (2007). McVerry, G.H. (2007). Newmont Mine spectra. GNS Science Hazard warning systems for the Gisborne district: assessment consultancy report 2007/178LR. 4 p. of options. Lower Hutt: GNS Science. GNS Science report 2007/04. 70 p. Auckland McVerry, G.H. (2007). Site-specific spectra for Puketutu Island, Tait, A. (2007). An analysis of snowfall and frost in the Mangere. GNS Science consultancy report 2007/173. iv, 14 p. Gisborne District. NIWA Client Report WLG2007–28. 29 p. McVerry, G.H. (2007). Earthquake spectra for State Highway 20 Tait, A.; Reid, S. (2007). An analysis of extreme high winds in bridges, Auckland. GNS Science consultancy report 2007/25. Gisborne District. NIWA Client Report WLG2007–25. vii, 21 p. Hawke’s Bay Rattenbury, M.S.; Dellow, G.D. (2007). Geological ground Dellow, G.D. (2007). Engineering geology of the Napier City conditions along the Vector Limited gas pipeline network in the Council water reservoir at Bay View. GNS Science consultancy Auckland region. GNS Science consultancy report 2007/352. report 2007/133. 29 p. ii, 14 p. Goff, J.R. (2007). Tsunami hazard assessment and coastal Reid, S. (2007). Meteorological report on the extreme weather inundation modelling – Hawke’s Bay (Modules 4 and 5). NIWA event on 9-10 November 2006 impacting on Waiheke Island. Client Report CHC2007–023. Prepared for Hawke’s Bay NIWA Client Report WLG2007–32. Prepared for Vector Regional Council. 22 p. Networks Ltd. Langridge, R.M.; Villamor, P. (2007). Hastings District LiDAR fault trace survey. GNS Science consultancy report 2007/145. 43 p.

28 Natural Hazards 2007 Taranaki Walsh, J.M. (2007). Steep Head directional wave buoy annual Massey, C. (2007). Waikorora Bluff landslide, north Taranaki: report - January 2006 to December 2006. NIWA Client Report movement monitoring report, May 2006 to December 2006. CHC2007–019. Prepared for Environment Canterbury. 24 p. GNS Science consultancy report 2007/34. 20 p., figs, maps. Walsh, J.M. (2007). Heathcote River and Henderson’s Basin Schmidt, J.; Salinger, J.; Woods, R. (2007). Climate hazards hydraulic model calibration. NIWA Client Report CHC2007– and extremes – New Plymouth District. NIWA Client Report 043 and 043R. Prepared for Christchurch City Council. 67 p. WLG2007–005. Prepared for New Plymouth District Council. Walsh, J.M. (2007). Heathcote River and Henderson’s Basin Sherburn, S.; Scott, B.J.; Miller, C.A.(2007). Data from the hydraulic model study. NIWA Client Report CHC2007–044 Taranaki Volcano-Seismic Network: July 2005 to June 2006. and 067. Prepared for Christchurch City Council. 39 p. GNS Science consultancy report 2007/06. ii, 20 p., figs, maps. West Coast Manawatu-Wanganui McVerry, G.H.; Downes, G.L. (2007). Magnitude of Buller McSaveney, M.J.; Page, M.J. (2007). The Totara Reserve earthquake 16 June 1929. GNS Science consultancy report Regional Park cliff collapse of 15 December 2006. Lower Hutt: 2007/42LR. 6 p., fig. GNS Science. GNS Science report 2007/11. 10 p. McVerry, G.H.; King, A.B. (2007). Stockton seismic hazard.

Smith, W.D.; Power, W.L.; Lukovic, B.; Cousins, W.J. (2007). GNS Science consultancy report 2007/05LR. 4 p., fig. studies Hazard Wanganui tsunami risk assessment. GNS Science consultancy report 2007/308. 10 p. Ramsay, D. (2007). Managing and adapting to coastal erosion on the west coast: Ngakawau and Hector. NIWA Client Report Wellington HAM2007–007. Prepared for West Coast Regional Council. 20 p. Baldi, M.; Burgess, S.; Mullan, B.; Salinger, D.; Ramsay, D.; Ramsay, D. (2007). Punakaiki seawall impacts. Technical note Bell, R. (2007). Updated climate change scenarios for the Kapiti for West Coast Regional Council. 03 January 2007. NIWA Coast. NIWA Client Report AKL2007–091. Prepared for Kapiti Client report HAM2007–014. 7 p. Coast District Council. 49 p. Ramsay, D. (2007). Reducing the risks caused by coastal Heron, D.W.; Townsend, D.; Van Dissen, R.J. (2007). Review erosion to Granity School. NIWA Client Report of 2003 earthquake fault trace survey following field work HAM2007–135. Prepared for the Dept. of Education. 23 p. in Maungakotukutuku Valley and Transmission Gully areas. GNS Science consultancy report 2007/246LR. 4 p. Smart, G.M. (2007). Waimangaroa River Bank Erosion, NIWA Client Report CHC2007–091 ELF07201/WCRC36. McVerry, G.H.; King, A.B. (2007). Taranaki Street site investigation using Nakamura technique. GNS Science Otago consultancy report 2007/14LR. 10 p., figs. McVerry, G.H.; Beetham, R.D.; Stirling, M.W.; Stephenson, McVerry, G.H.; Beetham, R.D.; Stirling, M.W.; Stephenson, W.R. (2007). Earthquake spectra and potential geotechnical W.R. (2007). Earthquake spectra and potential geotechnical hazards for Benmore switchyards. GNS Science consultancy hazards for Oteranga Bay cable station. GNS Science report 2007/240. ix, 62 p. consultancy report 2007/242. v, 55 p. Van Dissen, R.J.; Barrell, D.J.A.; Langridge, R.M.; Litchfield, Nelson / Marlborough N.J.; Villamor, P.; Tonkin, P. (2007). Reassessment of seismic Langridge, R.M.; McVerry, G.H.; Litchfield, N.J.; Destegul, hazard at Clyde Dam, Central Otago : Earthquake geology U. (2007). Assessment of seismic and fault hazards at Omaka field investigations and determination of Dunstan Fault rupture Downs, Marlborough. GNS Science consultancy report characteristics. GNS Science consultancy report 2006/147. 2 2007/379. vi, 47 p. vols, appendices. McVerry, G.H.; Beetham, R.D.; Stirling, M.W.; Stephenson, Southland W.R. (2007). Earthquake spectra and potential geotechnical Turnbull, I.M.; Glassey, P.J. (2007). Site stability assessment, hazards for Fighting Bay cable station. GNS Science Westies Cave: final report. GNS Science consultancy report consultancy report 2007/241. v, 55 p. 2007/78LR. 8 p., figs.

Canterbury International Goff, J.R.; Chagué-Goff, C. (2007). Avon-Heathcote Estuary Becker, J.S.; Johnston, D.M.; Coomer, M.A.; Ronan, K. (Ihutai): Palaeoenvironmental changes – Final stage report. (2007). Flood risk perceptions, education and warning in NIWA Client Report CCC07501. Prepared for Christchurch four communities in New South Wales, Australia: results of City Council. 22 p. a questionnaire survey, November 2005. Lower Hutt: GNS Halstead, I.; Tuck, I.; Hendrikx, J. (2007). Waitaki catchment Science. GNS Science report 2007/30. 66 p. snow report 2006–2007 season: Panorama, Rose, and Mueller Robinson, R.; Rhoades, D.A. (2007). Preliminary study of snow courses. NIWA Client report MEL07501. Prepared for accelerating moment release (AMR) in recent Italian seismicity. Meridian Energy Ltd. GNS Science consultancy report 2007/345. ii, 9 p. Langridge, R.M.; Duncan, R.; Almond, P.; Robinson, R. (2007). Scott, B.J.; Gledhill, K.R.; Cronin, S.J. (2007). A volcano-seismic Indicators of recent paleoseismic activity along the western monitoring system for Vanuatu. Final scoping report. GNS Hope Fault. GNS Science consultancy report 2006/151. iv, 115 p. Science consultancy report 2007/136. v, 33 p. Lewis, M.J.; Bell, R.G. (2007). Sumner Head Sea-Level Station: Stirling, M.W. (2007). Preliminary estimates of maximum Annual Report for 2006. NIWA Client Report HAM2007–067. ground motions at Yucca Mountain: review of recent studies. Prepared for Environment Canterbury. 25 p. GNS Science consultancy report 2007/148. 8 p. Lewis, M.J.; Bell, R.G. (2007). Timaru Sea-Level Station: Stirling, M.W.; Peruzza, L.; Slejko, D.; Pace, B. (2007). Annual Report for 2006. NIWA Client Report HAM2007–068. Seismotectonic modelling in northeastern Italy. GNS Science Prepared for Environment Canterbury. 31 p. consultancy report 2007/84. ii, 19 p., figs, maps. Tuck, E.; Halstead, I. (2007). Waitaki Catchment snow survey 19 December 2006. NIWA Client report WLG2007–04. Most of the reports listed here are prepared under contract for clients: Prepared for Meridian Energy Ltd. 10 p. contact the authors for more details of availability.

Natural Hazards 2007 29 Science contributors to Natural Hazards 2007 Contributors

Doug Ramsay Wendy Saunders Rob Bell Kelvin Berryman Kevin Fenaughty Andrew King

Vern Manville Stefan Reese Graeme Smart Michael Uddstrom Murray Poulter Terry Webb

Doug Ramsay Kevin Fenaughty Dr Graeme Smart Coastal Consultant, NIWA GeoNet Data Centre Manager, GNS Science Rivers Consultant, NIWA Doug coordinates coastal consultancy work in Kevin is responsible for the running of the Graeme has expertise in the fields of NIWA’s Hamilton office and leads the NIWA GeoNet data centre, including the data hydrology, river control, and sediment component of the Natural Hazards Centre. He collection systems, the analysis of earthquakes transport. He is currently leading the work is involved with work both in New Zealand and the release of hazards information. A on high-resolution flood-inundation hazard and the Pacific Islands on understanding and particular interest is ensuring that GeoNet’s mapping which uses remotely sensed data managing coastal hazard risk and the impacts information is accessible to a wide audience to determine ground topography, surface of climate change on these risks. Doug that includes emergency managers, academic roughness, flood depths, and water velocities. coordinated the production of this annual researchers, and the community at large. review in conjunction with Wendy Saunders. Dr Michael Uddstrom Andrew King Science Leader, Environmental Forecasting, Wendy Saunders Section Manager, Active Landscapes, GNS and Programme Leader, Reducing the Impact Natural Hazards Planner, GNS Science Science and Co-Leader, RiskScape New of Weather Related Hazards, NIWA Wendy is involved in researching policy and Zealand JV Michael’s research interest is in the use planning for natural hazard risk reduction, Andrew manages the Geohazards Solutions of satellite observations of atmospheric which has included compiling landslide section of GNS Science. He is a civil engineer emissions to improve the accuracy of weather guidelines for consent and policy planners. with specialist knowledge in structural forecasts, and hence of the entire downstream Wendy coordinated the production of this engineering, particularly the response modelling system. annual review in conjunction with Doug of the built environment to earthquakes. Ramsay. Andrew coordinates the RiskScape research General Managers programme in conjunction with Rob Bell. Dr Rob Bell Dr Murray Poulter General Manager, Atmosphere, Natural Science Leader, Natural Hazards, NIWA and Dr Vern Manville Hazards, & Energy, NIWA Co-Leader, RiskScape New Zealand JV Scientist, Volcanic Hazards, GNS Science Murray is General Manager of NIWA’s Rob is NIWA’s Science Leader for natural Vern is leading the science project designed atmosphere research and consulting portfolio, hazards research and consultancy work. to capture maximum benefit from Ruapehu’s which includes natural hazards, atmospheric His specialities are coastal hazards and the crater lake break-out lahar. He has been pollutants, and renewable energy. Within effect of climate change. Rob coordinates studying volcano-hydrologic hazards and the natural hazards area this covers weather, the RiskScape research programme in landscape responses to volcanic activity on flooding, and coastal-related hazards, the conjunction with Andrew King. the Pacific Rim for over 12 years. impacts of climate change on these hazards, Dr Kelvin Berryman Dr Stefan Reese and development of forecasting systems. Hazards & Society Programme Leader, GNS Risk Engineer, NIWA Dr Terry Webb Science Stefan has a background in physical General Manager, Natural Hazards, GNS Science Kelvin manages ten objectives under geography and specialises in the physical and Terry manages the Natural Hazards Group at the programme, which aims to develop socio-economic impacts of different types of GNS Science and is thus responsible for the quantitative estimates of geological hazards, hazards such as tsunamis, river floods, storm Group’s research and consultancy services in and evaluate how New Zealand society is surges, and wind events. Other research the areas of geological hazards (earthquakes, addressing these perils. interests are climate change impacts, social volcanoes, landslides, and tsunami) and vulnerability, risk perception and planning for geological mapping. Management of natural hazard risk reduction. Stefan is also the EQC-funded GeoNet project is also a heavily involved in the RiskScape research responsibility of the Group. programme.

30 Natural Hazards 2007 Acknowledgments

Publication of Natural Hazards 2007 was funded by NIWA and GNS Science with additional financial support from the Ministry of Civil Defence and Emergency Management (MCDEM) and Ministry for the Environment (MfE).

A number of other people provided valuable contributions to Natural Hazards 2007, including: Anna Altenberger, Stuart Burgess, Dr Giovanni Coco, Dr Terry Hume, Dr Andrew Lorrey, Dr Hilary McMillan, Dr Richard Turner (NIWA); and Grant Dellow, Dr Mark Stirling, Dr Graham Leonard, Dr Hannah Brackley, Brad Scott (GNS Science).

We are also grateful for contributions from our external collaborators, including: Richard Smith (MCDEM), Joanna Martin (EQC), John Lucas (Insurance Council), and Trecia Smith (MfE).

Production was by Harriet Palmer and Wendy St George (NIWA). Short courses and conference in 2008 In 2008 the Natural Hazards Centre will be running four two-day courses (with optional field trips) focusing on understanding natural hazards, and on ways that individuals, communities, organisations, and government can plan to avoid and manage the consequences of such hazards. The Natural Hazards Centre is also coordinating a major international conference in July 2008. conference and courses Short

Our courses are aimed at anyone with an interest, or role, in assessing, managing or communicating the risks associated with natural hazard events including: • planners nd • emergency managers 2 Australasian Natural Hazards • educators • engineers Management Conference 2008 • utility and asset managers • local, regional and central government policy makers. From warnings to effective response and recovery Understanding and Managing Earthquake Hazards Wellington, 15–16 May, 2008 Managing Extreme Weather and Flooding Wellington, 18–19 September, 2008 Planning for a Volcano Crisis Rotorua, 24–26 September, 2008

Understanding and Managing Landslide Hazards Photo: Wellington city and fault, GNS Science Photo Library Wellington, 5–7 November, 2008 Te Papa, Wellington, New Zealand For more information on these courses and to 29-30 July 2008 download the course brochures got to: Optional Workshops 28 & 31 July 2008 www.naturalhazards.net.nz/courses

The conference will provide a forum to discuss the integration of hazard The Managing Coastal Hazards course will return in information into effective risk management, including: 2009. A number of other workshops with coastal (and • Applying hazard information to best practice planning other weather-related hazard) content will be run in • Developing effective warning systems • Improved response and recovery from events 2008 including: • Creating resilient communities through integrating science into practice Coastal Climate Change: Planning on rising sea-levels Our target audience is: Emergency managers, planners, risk assessors, asset and utility managers, natural hazards researchers and scientists. Workshop at the NZ Planning Institute conference, Shantytown, Greymouth, 3–5 April, 2008 Further information is available on the conference website at: Incorporating climate change into engineering design www.hazards-education.org/ahmc/2008/2008index.php (run by IPENZ) Taupo, 19 August, 2008 Auckland, 11 September, 2008 Christchurch, 2 October, 2008 Front and back cover: After the 25 September blue sky eruption, Mt Ruapehu. Photos: Vern Manville, GNS Science.

Natural Hazards 2007 31

The Natural Hazards Centre The Natural Hazards Centre was established in 2002 by NIWA and GNS Science, New Zealand’s leading hazard Crown Research Institutes. Its role is to provide New Zealanders with a single point of contact for the latest research, resources, and scientific expertise. Its strength lies in multidisciplinary skills, all-hazard coverage, and resources for delivering world-class research to emergency and resource managers, the science community, planners, and policy makers. www.naturalhazards.net.nz

A joint publication by NIWA and GNS Science Enquiries to: Science Communication, NIWA, Private Bag 14901, Kilbirnie, Wellington NIWA Information Series No. 67 ISSN 1174-264X or Communications Manager, GNS Science, PO Box 30368, Lower Hutt GNS Science Miscellaneous Series 14 ISSN 1177-2441 www.niwa.co.nz www.gns.cri.nz

This publication is printed on paper produced using chlorine-free processes, from timber harvested from sustainably managed forests. The printer uses mineral-free inks and recycles cartridges, waste paper,

The Canterbury [Cover snowstorm, photos: , GNS] July 2007. aluminium plates, and used cartridges. Waste chemicals are collected and destroyed by a certified company.