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Civil Defence and Emergency Management SCHOOL OF ENVIRONMENT From science to practice: bridging the gap through the Determining Volcanic Risk in Auckland (DEVORA) project Jan Lindsay1 and Gill Jolly2 1School of Environment, The University of Auckland, New Zealand; 2GNS Science, Taupo, New Zealand volcano volcano volcano volcano volcano volcano volcano volcano volcano volcano Photo courtesy of Lloyd Homer, GNS Science Auckland population: 1.5 million, ca. 1/3 of national population AVF: one of 3 potentially active intraplate volcanic fields in NZ Other fields: Kaikohe-Bay of Islands and Whangarei Fields SCHOOL OF ENVIRONMENT · Geology Auckland Volcanic Field ca. 50-55 small “monogenetic” basaltic centres Hayward et al. (2011) SCHOOL OF ENVIRONMENT · Geology Types of volcanoes Maars or explosion craters (e.g. Lake Pupuke, Orakei basin, Onepoto Domain) Scoria/cinder cones (e.g. Mt. Eden, Mt. Wellington, Mt. Albert) SCHOOL OF ENVIRONMENT · Geology Spatio-temporal relationships Rangitoto: 550 – 600 years ago Pupuke erupted about 250,000 years ago SCHOOL OF ENVIRONMENT · Geology Will the AVF erupt again? • Such fields can be long- lived (> 1 million years), AVF ~ 250,000 yrs • Last eruption 550 yrs ago Horspool et al. (2006) Mantle anomaly 70-90 km beneath Auckland = partially molten mantle?? SCHOOL OF ENVIRONMENT · Geology Slide courtesy Greg Auckland CBD Holland, Auck. Council SH1 Parnell Grafton Newmarket Epsom SH16 Remuera Greenland Mt Eden One Tree Hill Oranga Royal Oak Three Kings Mt Eden Sandringham St Lukes Balmoral Population: 223,000 Morningside West’n Springs Businesses: 38,000 Kingsland Grey Lynn Employees: 204,000 Ponsonby SCHOOL OF ENVIRONMENT · Geology Herne Bay Volcanic Risk = (hazard, vulnerability) Auckland is vulnerable. So, even though the probability of the “hazard” of an AVF eruption is low – the risk is not low. An eruption in Auckland would be a low probability, high consequence event “DEtermining VOlcanic Risk in Auckland” A UoA-GNS Science collaborative project Project aim: a much-improved assessment of volcanic hazard and risk from the Auckland Volcanic Field & ash fall from Central North Island volcanoes Core Funding: EQC, Auckland Council, MBIE, GNS Science, UoA Co-funding: Massey, Victoria, Canterbury Universities, Marsden, VORiSA Regular engagement with all partners (e.g. EQC, Civil Defence, Lifelines) Determining Volcanic Risk in Auckland (DEVORA) A UoA-GNS Science collaborative project Three main themes: Geological Model Probabilistic Hazard Model Risk and Social model currently in 6th year of a 7 year project. 30 Researchers & 10 PhD students across 9 institutions Theme 1: Geological model • Using geochemistry to understand how volcanic systems work Determining the conditions of magma genesis – depth, degree of partial melting, source characteristics. Defining trends within individual volcanoes to establish the type of processes that have modified rising magma and provide constraints on the rates of magma ascent • Using structural geology to identify volcanic pathways Statistical analysis of vent locations Using geological (incl. borehole) and geophysical data • Integration and development of geological model SCHOOL OF ENVIRONMENT · Geology Theme 2: Hazard model Refining hazard knowledge • Field studies and modelling of base surge, lava flows, gas, ash Determining magnitude-frequency relationships • Reassessing old ages (C14, K-Ar, Ar-Ar) • New C14, Ar-Ar and Paleomag proxy ages • Tephrochronology • Correlation of ash layers with source volcanoes Spatio-temporal modelling • BET VH/EF • Scenario probability matrix • Refine all models and develop for RiskScape SCHOOL OF ENVIRONMENT · Geology Theme 3: Risk and Social Model Impacts (determining vulnerability) • Exposure database (assets) • Fragility of Auckland’s infrastructure, buildings, and population • Intangible and indirect impacts Societal response • Determine best risk assessment and risk communication methods • Development of tools for improved societal response Calculate Volcanic Risk! SCHOOL OF ENVIRONMENT · Geology Recent discovery !! Thin basaltic tephra layers in Lake Pupuke that are 1,500 years old suggest Rangitoto may have erupted several times over 1,000 years Not reworked The Volcanoes, the City and the Borehole Database #0 #0 #0 #0 #0 #0 #0 #0 #0 #0 #0 #0 #0 #0 #0 #0#0 #0 #0 #0 #0 #0 #0 #0 #0 #0 #0#0 #0 #0 #0 #0 #0 #0 #0 #0 #0 #0#0 #0 #0#0 #0 #0#0 #0 Eruption Types and feeding systems - Auckland Jeju - magma evolves due to crustal/mantle modification Brenna et al., 2012, Lithos Controls on Auckland hazards Magma Volume, rise rate, ejection rates Magma properties: composition, gas, temperature, crystalinity etc. Environmental Properties Water, surface, saturation Country rock, structure, strength Topography Orakei Basin Study Nemeth et al. 2012 Bull Volcanol increasing water saturation of Plio-Miocene strata increasing thicness of Plio-MioceneSaturation strata increasing probaility of water filled fractures increasing probability of embeddedWater pressurisedsupply ground water in Miocene rock untis increasing standing waterDepth depth of soft sediment initial volcanic hazards dominate: external forcing external dominate: hazards volcanic initial External vs. internal factors for hazard for eruption factors vs. internal External increasing magma supply rata, magma flux magma rata, supply magma increasing Magma Supply Supply Magma Rate steady stage volcanic hazards dominate: internal forcing internal dominate: hazards volcanic stage steady Substrate matters Central-Nth Auckland – Waitemata Group – firm, dense rocks South Auckland – Soft, saturated sediments Play a major role in how volcanic eruptions occur Spatial classification of eruption scenario probabilities Substrate geology/water Past eruption type Volcano substrate is a critical factor for hazard Maungataketake, South Auckland Magma ponded in wet soft rock Eruptions low-energy “excavations” What about submarine volcanism? One of the few submarine volcanoes – North Head Most of the rest of the volcanoes erupted at periods of low-sea levels Agustin-Flores et al, in prep Lava flow hazards 1. Geomorphic modelling approach – using high precision LiDAR Kereszturi, et al., 2012 Remote Sensing of Environment Lava flow simulation codes (MAGFLOW) Best fit scenario (5000h) Three Kings Duration ~208 days volcano effusion rate = 5 m3/s Input into hazard scenarios… Kereszturi et al., in prep Auckland Civil Defence Emergency Where are we going with Management (CDEM) Group Plan 2011-2016 all this? 1 Oct 2009 www.stuff.co.nz SCHOOL OF ENVIRONMENT · Geology RiskScape Moving towards a quantitative volcanic risk assessment framework SCHOOL OF ENVIRONMENT · Geology Thanks to the team.
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