SCHOOL OF ENVIRONMENT

From science to practice: bridging the gap through the Determining Volcanic Risk in (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 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, , 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 External vs. internal factors for eruption hazard

increasingMagma magma Supply supply rata,Rate magma flux

steady stage volcanic hazards dominate: internal forcing Saturation supply Water Depthsoft of sediment

initial volcanic hazards dominate: external forcing increasing water saturation of Plio-Miocene strata ofPlio-Miocene saturation water increasing increasing thicness of Plio-Miocene strata Plio-Miocene of thicness increasing increasing probaility of water filled fractures filled of water probaility increasing increasing probability of embedded pressurised ground water in Miocene rock untis rock in Miocene water ground pressurised of embedded probability increasing increasing standing water depth water standing increasing 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