Between a rock and a simulated space: Lava inundation probability

James Madison University Geology and Environmental ScienceSeminar Series 1/19/2013

Julie A. Herrick

Intro To Volcanic Hazards

October 1st, 2004

Precursory Activity

New Technologies

Communication

HAWAI’I

MAUNA LOA

MAUNA KEA

HUALALAI

KILAUEA

KOHALA

51%

Modified from Lockwood, 1976

Primary Features of Big Island Volcanism

Summit Crater

Rift Zones: NE and SW

Radial Vents: N flank

Zonation: Red Yellow Blue

“Over the past 3,000 years it has erupted lava flows, on average, every 6 years.

Since 1843, Mauna Loa has erupted 33 times, averaging one eruption every 5 years.”

~ USGS Fact Sheet ‘12

Mauna Loa Observatory (MLO) area

N

Mauna Loa Observatory (MLO) area

600 m350 m

Facility was operating in 1956

Barrier constructed in 1986

GOAL

TOOLS

WHY?

HAZARD assessment• Lava flow paths• Inundation zones• Inundation probability

• NOAA MLO Hazard assessment

• Isolated target (within our scope)• High vulnerability• Continued expansion of facilities

• Detailed geological map (5.5 x 2.5 km)• DEM 10 m• 1984 topography

BASINVORIS

Rift

Moku’aweoweo

Mauna Loa Weather Observatory

1956 Observatory established

1984: Flow from NERZ

Barrier construction in 1986

NE Rift Zone

Summit Crater

Radial Vents

1984

Rad

ial V

ents

S

Field Area: ~14 km2

• # Lava Flows: 41

• Radial Vents

• Spatter Ramparts

• Cinder Cones

• North Pit Crater

• Collapse Crater

• Lava Tubes

• Pahoehoe

• A`a

Geological Map

Spatial Distribution Zone Susceptibility

Qualitative data Quantitative data

+ +

Flow network Probability distributionBASIN VORIS

Inundation zones • Flow simulation• Occurrence probability

cont

rol control

DEM DEM

Ivan Petras 2000, for hydrological studies.

Flow direction grid

Flow accumulation grid(Cell Flow Accumulation)

- Computing the cumulative cell count upstream each cell

- Cells with high CFA lie in major channel

- Cells with zero CFA identify a ridge

BASIN

N

BASIN Analysis: Sensitivity Testing

Topography: good agreement

Mapped channels: good agreement

FLOW NETWORK with CFA=400

Threshold:CFA=cell flow accumulation

BASIN Analysis: Results

OBSERVATIONS • Branches following contacts (eg. old pahoehoe, new a’a)

• Branches cutting old flows (tumulus and channels)

• 4 Zones ~= 4 Basins

• All zones can be affected by the summit caldera, North Pit Crater

ERRORS• DEM has no major errors

• Errors occur where small topographic variations

BARRIERS • One branch follows the main western barrier

BASIN Analysis

4 NEW inundation zones

• rift + summit caldera• rift + summit caldera + radial vents

• summit caldera + radial vents

All zones can be affected by the summit caldera, North Pit Crater

Three radial vents shared by two zones:more lava directions due to vent complexity

Geographic Controls

1. Each future eruption will occur independently (eg. will not be related to the timing of previous eruptions).

2. The probability that an eruption will occur in a future time interval will not change with the passage of time.

3. The probability that an eruption will occur in a particular time interval is proportional only to the length of that interval.

4. The probability of more than one eruption occurring in the same time interval is very small.

P = 100 (1 – e-t I T )

(Lockwood and Hazlett, 2010; Davis 1986)

Analysis #2

Occurrence probability in a 50 yrs time period

POISSON Probability

Recurrence time = Oldest flow age

Total # of flows

4 vent classes

Radial vents

Rift vents

W N Pit crater

E N Pit Crater

VORIS

VORIS: theory and advantages

From Felpeto et al., 2002

Topography plays the major role

DEM

• Probability proportional to the difference in height

• can test various flow thickness (Hc)

• can test LAVA SOURCES

and their SUSCEPTIBILITY

1984 lava flow simulation

• known history (summit and rift vents)• fluid shelly pahoehoe, does not alter the

topography

1984 flow chosen because of:

Sources: two points are sufficient

Tephra high Tephra high

NOAA MLO natural topographic protection • Punctual vents to open outside the barriers

• as close as possible to the barriers• located on flow network branches

SOURCES

Hc

Major threat

Well diverted

1852 high ground: good topographic protection

CONCLUSIONS

W B

arrier

• Barriers planned well!

• Low risk to MLO from rifts

• High risk from radial vents and North Pit Crater (W edge)

Escape road, to HWY200

Easy to read inundation zones map + probability of lava inundation

long term land use planningemergency defense plan

• Western barrier is a success

• Escape road is at risk (eg. 1975)

Thanks!

Dr. Anna Courtier,James Madison University

Erika Ronchin, Institute of Earth Sciences Jaume Almera (CSIC),

Grupo de Volcanología de Barcelona (GVB-CSIC), & SIMGEO (UB-CSIC)

Frank Trusdell, Hawaiian Volcano Observatory, USGS

Jack Lockwood, Geohazards Consultants International, Inc.

Lava Diversion Methods

1983 lava flows from Mount EtnaSapienza resort and tramway complex