"The combination of geologic field mapping and geospatial methods allowed us to demonstrate the probability of lava flow inundation for an important location on the N flank of Mauna Loa. We focused on the 2.5 x 5.5 km area from radial vents, rift zones, and the summit crater that encompasses the NOAA weather station (MLO). Field investigations conducted in 2005 determined that 30 unique geologic units cross this study area and originated from the summit, radial vents, and the NERZ. We combined two DEM-based simulation models to provide a detailed examination of lava flow paths with the purpose of developing a hazard assessment for the NOAA facility. Two GIS computer software programs (BASIN1 and VORIS) were used to analyze the digital terrain based on a 10 m DEM in order to outline possible inundation zones. The advantage of the BASIN1 results is that they provide clear delineations of the flow network. Subsequently, preliminary inundation zones were drawn based on model results. Additional information provided by VORIS defines the probability of each flow network branch being inundated. By overlapping the inundation zones with the map of inundation probability within a 50-year time interval, it is clear that the NOAA Facility should not be affected by lava flows originating from the NERZ. The main threats are from lavas originating from the western edge of Moku`aweoweo and the potential formation of radial vents."

1. Between a rock and a simulated space:
Lava inundation probability
James Madison University
Geology and Environmental Science
Seminar Series 1/19/2013
Julie A. Herrick

3. Intro To Volcanic Hazards
October 1st, 2004

4. Precursory Activity

5. New Technologies

6. Communication

8. KOHALA
MAUNA KEA
HUALALAI
MAUNA LOA KILAUEA
51%
HAWAI’I

9. Primary Features of Big Island Volcanism
Summit Crater
Rift Zones: NE and SW
Radial Vents: N flank
Zonation:
Red
Yellow
Blue
Modified from Lockwood, 1976

10. “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

11. Mauna Loa Observatory (MLO) area
N

12. Mauna Loa Observatory (MLO) area
Facility was operating in 1956
350 m Barrier constructed in 1986
600 m

13. GOAL HAZARD assessment
• Lava flow paths
• Inundation zones
• Inundation probability
TOOLS • Detailed geological map (5.5 x 2.5 km)
• DEM 10 m
• 1984 topography
BASIN
VORIS
WHY? • NOAA MLO Hazard assessment
• Isolated target (within our scope)
• High vulnerability
• Continued expansion of facilities

14. Mauna Loa Weather Observatory
1984 Moku’aweoweo
Summit Crater
NE Rift Zone
Radial Vents
 1956 Observatory established
 1984: Flow from NERZ
 Barrier construction in 1986
S

15. Field Area: ~14 km2
• # Lava Flows: 41
• Radial Vents
• Spatter Ramparts
• Cinder Cones
• North Pit Crater
• Collapse Crater
• Lava Tubes
• Pahoehoe
• A`a

16. Geological Map
Qualitative data Quantitative data
Spatial Distribution Zone Susceptibility
+ +
DEM DEM
Flow network Probability distribution
BASIN VORIS
Inundation zones • Flow simulation
• Occurrence probability

17. BASIN
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

18. BASIN Analysis: Sensitivity Testing
Threshold:
CFA=cell flow accumulation
Topography: good agreement
Mapped channels: good agreement
N
FLOW NETWORK with CFA=400

19. 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
BARRIERS • One branch follows the
main western barrier
• DEM has no major errors
ERRORS
• Errors occur where small
topographic variations

20. 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

21. Geographic Controls

22. Analysis #2
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)

23. Occurrence probability in a 50 yrs time period
4 vent classes
Oldest flow age
Recurrence time =
Total # of flows
Radial vents
VORIS
POISSON Probability
Rift vents
W N Pit crater
E N Pit Crater

24. VORIS: theory and advantages
Topography plays the major role • Probability proportional to the difference in height
• can test various flow thickness (Hc)
• can test LAVA SOURCES
and their SUSCEPTIBILITY
DEM
From Felpeto et al., 2002

25. 1984 lava flow simulation
1984 flow chosen because of:
• known history (summit and rift vents)
• fluid shelly pahoehoe, does not alter the topography
Sources: two points are sufficient
Tephra high Tephra high

26. NOAA MLO natural topographic protection
SOURCES • Punctual vents to open outside the barriers
• as close as possible to the barriers
• located on flow network branches
Hc
Major threat
Well diverted
1852 high ground: good topographic protection

27. CONCLUSIONS
• Low risk to MLO from rifts
• High risk from radial vents and North
Pit Crater (W edge)
• Western barrier is a success
• Barriers planned well!
• Escape road is at risk (eg. 1975)
Escape road, to HWY200
Easy to read inundation zones map + probability of lava inundation
emergency defense plan long term land use planning

28. 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.

30. Lava Diversion Methods
1983 lava flows from Mount Etna
Sapienza resort and tramway complex