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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