Ash Fall Impacts: what really matters?

Ash Fall Impacts:

what really matters?

Tom Wilson

; Andrew King

;

Carol Stewart

_{; Graham}

Leonard

_{; Natalia Deligne}

;

Overview



_{NZ Research programme}



General context



Focus on building impacts



Observations from field surveys



Laboratory experiments



_{Impacts to urban environments...what is}

important?

New Zealand Research Programme



_{Mid 1990’s – present}



need to develop a greater evidence-base of

volcanic impacts to enhance preparedness and

mitigation decision making (particularly for ash

fall)



1995-96 Ruapehu eruption catalyst



_{Riskscape and DEVORA Projects (2010-}

present)



Quantitative volcano loss model – initial focus

Research Context – Ash Impact Research

• _{Over the past 20 years our New Zealand research}

group (and collaborators) have aimed to undertake a sustained and systematic approach to volcanic impact assessment

- _{critical infrastructure: electricity, water supplies,}

wastewater, land and air transport, telecommunications

- _{ash cleanup and disposal}

- _{primary industries, e.g. agriculture} - _{social impacts}

- _{emergency management}

• _{Reconnaissance trips to impacted areas to bring}

lessons home

• _{Followed by laboratory testing of critical infrastructure}

Recon Trips:

by volcano & year visited

Eldfell (Heimaey) 2008 Eldfell (Heimaey) 2008 Redoubt 1996; 2010

Redoubt 1996; 2010

Pinatubo 2007 Pinatubo 2007 Merapi 2006 Merapi 2006 Sakurajima 2001 Sakurajima 2001 Shinmoedake 2011 Shinmoedake 2011 Ruapehu 1995-96 Ruapehu 1995-96 Lapevi 2003-05 Lapevi 2003-05 Hudson 2008 Hudson

What pops up time after time...

 _{Health (most important!)}

 _{What does ash do to me….to my children?}  _{What will ash do to water supplies?}

 _{What impact will it have on food?}

 _Farming

 _{What will ash do to my animals and crops?}  _{How can I remediate the damage?}

 _{How much Fluoride is in the ash?}

 _{Infrastructure}

 _{Clean up – difficult and expensive (time & $}

$ )

 _{Didn’t expect those impacts.}  _{Wish we had planned for this…}

 _{Business Disruption}

 _{Difficult to clean up. Is it safe to remain?}  _{How do we get the tourists back?}

 _{Government level – what are the losses?}



_{Volcanic ash falls are often regarded as exotic}

Which hazard intensity?



_Loading?



_Thickness?



_{Duration of fall?}



_Grainsize?



_{Agriculturally}

Building Damage Observations

 _{Structural damage from ash loading has been}

rarely observed by our group

 _{Acknowledging Rabaul, Pinatubo, etc}

 _{Futaleufú, Chile (Chaiten, 2008)}  _{75 mm + snow}

 _{Long span roof (gym) began deforming (not}

built to snow code)

 _{Villa La Angostura, Argentina (PCC, 2011)}  _{75-100 mm + rain}

 _{Non-snow code (pre-1980’s) residential}

houses require extra bracing

 _{Shinmoedake, Japan (Shinmoedake, 2011)}  _{Long span roof (agricultural feedlot)}

collapsed CHAITEN

Ash damage to buildings

1. Structural

 Observations rare

2. Envelope: non-structural elements

 _{Gutter damage is very common (when fitted)}  _{Corrosion of metal roofs}

3. Fittings : systems which allow building to function

 _{HVAC systems vulnerable to disruption} 4. Contents and Plant

 _{Contamination of the interior space}  _{Clean up is expensive + on-going}

 _{Actual loss is dependent on all these elements,}

which act as an interdependent system

Chasing D1: Laboratory experiments



_{Dynamics ash deposition on roofs – what}

actually happens?



_{How vulnerable are gutters?}

Behaviour of ash on sheet metal roofs + gutter

vulnerability

Hampton, S.J., Cole, J.W., Wilson, T.M., Wilson, G., (in prep). Volcanic ash

Volcanic ash accumulation and shedding relative to roof

pitch (50 mm/40kg/m

_{deposition of ash)}

Hampton, S.J., Cole, J.W., Wilson, T.M., Wilson, G., (in prep). Volcanic ash

Sheet metal roof corrosion from ash deposition

Oze, C., Cole, J.W., Scott, A., Wilson, T.M., Wilson, G., Gaw, S., Hampton, S.J., Doyle, C., Li, Z., (accepted). Corrosion of metal roof materials related to

 _{No significant corrosion}

was macroscopically or microscopically present on any roofing surfaces despite the presence of corrosive salts after a duration of 30 days

 _Suggests

ash-leachate-related corrosion is not a major or immediate

concern in the short term (~1 month)

 _{Ash still present after}

brushing – suggesting power washing might be required

Oze, C., Cole, J.W., Scott, A., Wilson, T.M., Wilson, G., Gaw, S., Hampton, S.J., Doyle, C., Li, Z., (accepted). Corrosion of metal roof materials related to

NZ approach to ash fragility functions for

buildings?



_Currently

 Very basic: long span vs. short span



_{Planned Work (<12 months)}

 _{Direct structural damage from ash and PDC}

 _{Is this really significant? What is the likelihood of ash}

deposition which might cause structural losses

 _{Guided by the NZ snow loading code}  Light industrial = problem

 Residential = ok

 _{Building Vulnerability Schema}  Roof structure information

Beyond buildings



_{Buildings are only a small portion of the}

problem.



Agriculture



_{Clean up}



Tourism



Aviation...



_{Business continuity impacts}

Impacts to the built

environment from large

silicic tephra falls



_{New Zealand and}

Patagonia share

similar:



_Latitude

_Volcanoes



_{Climate (esp. west}

)

References:

• PCC: Villarosa et al.

unpub data

• _Chaiten: Watt et al. 2009; Alfano et al. 2011

• Hudson: Scasso et al. 1994 40°S 50°S Puerto Ibanez Chile Chico Los Antiguos Tres Cerros

Puerto San Julian Perito Moreno Chaiten

Futaleyufu Esquel

Trevelin Villa La Angostura

Bariloche

CHAITEN

HUDSON PCC

Jaccobacci

1991 Hudson Eruption

• VEI 5

• 4.3 km3 _{bulk volume}

• 100,000km2 _affected

• Trachyandesite-rhyodacite

2008 Chaiten Eruption

• VEI 4

• 0.5-1.0 km3 _{bulk volume}

• 150,000km2 _affected

• Rhyolite

2011 Puyehue Cordon-Caulle Eruption

• VEI 4

• ~4.5 km3 _{bulk volume}

• 150,000km2 _affected

2008 Chaiten eruption, Chile

75 mm of ash fall induced infrastructure failure in Futaleufu, Chile (2,000 residents -

temporary evacuation)

• Water supply compromised

• Power supply cut

• Roads disrupted by thick ashfalls

• Health concerns Compounded effects

Eruption HUDSON 1991 CHAITEN 2008 PUYEHUE CORDON-CAULLE ₂₀₁₁ Town Affected Puerto _Ibanez Chile Chico _AntiguosLos _MorenoPerito _CerrosTres _{San Julian Chaiten Futaleyufu Trevelin}Puerto Esquel _{Angostura Bariloche Jaccobacci}Villa La Distance from Vent

(km) 90 120 125 175 473 545 11 75 100 110 44 90 231

Ash hazard

character-istics

Thickness of

ash fall (mm) 20 100 80 20 40 5 20 30 15 10 150 40 35

Duration of

main ash fall 4 days 4 days 4 days 4 days 2-4 days 2-4 days 3 days 6 days 4 days 2-3 days 5-6 days 5-6 days 5-6 days Remob of

ash

(duration) 15 years 15 years 15 years 15 years

5-10

years years5-10 0.5-4 years 1-2 years months6-18 months6-18 months6-12 months6-12 months>18

Critical Infra-structure Power Water Ground Transport Waste-water & Sewage Telecom Municipal

Cleanup Undertaken_Duration Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Evacuation

of population

Official Evac Yes No No No No No Yes Yes No No No No No Self evac –

immediate <50% <50% <30% <25% >75% <5% 100% >50% <5% <5% <20% <5% <20% Self evac -

long term <50% Yes Yes Yes >75% Yes >50% -- -- -- ??? --

--DURATION Hour(s) Day(s) Month(s) Year(s) SEVERETY

Few isolated issues Widespread outages Total disruption

Electrical + Water: high dependence  high

disruptive impact

System design key factor

Ground transportation: most common and often longest

disruption.

Roads (and properties) require clean up  costly and time

General findings for infrastructure



_{Loose relationship with ash thickness/load, but}

strongly influenced by:

system design



level of planning



adaptive capacities + mitigation actions (clean ash

off roof)



_{The complex characteristics of volcanic ash can}

create a range of possible

direct

and

indirect

impacts



Possibly leading to complex, cascading effects

_{Individual case-by-case assessment approach}

Kaharoa

Eruption Model

•

Based on 1315 A.D.

Fragility

functions

Relate hazard

intensity (X)

and fragility

(Y)

Probability can

be loss,

replacement,

etc.

Link is then

made between

hazard and

inventory via

fragility

function

Seasonal Vulnerability

•

Dairy farms carry out

different activities

throughout the year

•

Creates variable

Seasonal Vulnerability

•

Seasonality Coefficient

– only applicable to production

loss

Estimated Losses

Eruption Scenario Number of Exposed Dairy

Farms

Estimated Loss

High Vulnerability Low Vulnerability

Kaharoa 8,760 $2,970 million $2,440 million Inglewood 4,884 $1,120 million $911 million Ruapehu 2,368

(trace ash included)

$1.34 million $0.91 million

• Compare to 1 in 100 year Manawatu flood loss estimates

Volcanic Ash Testing Lab



_{Identified some components/systems}

are vulnerable, or might be vulnerable



Laboratory testing in controlled

environment



_{Electricity – flashover (AELG-19)}



_{Water – coag/floc}



_{Computers – damage & function loss}



_{GenSets – filter fragility/replacement}

Clean String

Evacuatio

n

following

Ash Falls

supplies Critical Infrastructu re failure (power, water, etc.) Anxiety of ash contaminatio n of water

supplies



_{Official evacuations rare}



_{But self-evacuation very}

common



_{Persistence of ashy}

conditions (

direct or

reomob

) will influence

duration of evacuation



_{Few evacuation from fear}

of roof collapse

 insufficient ash loads



_{Remobilisation of ash (esp. on regional scale) is just as}

disruptive as primary fall as it extends

duration of impact