Between a rock and a simulated space: Lava inundation probability


Published on

"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."

Published in: Education
  • Be the first to comment

  • Be the first to like this

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide
  • My supervisor says to me: Welcome to The Big Island, the place where you’ll learn that no other volcanic terrain is so difficult to map. Big grin.“If the endless sea of aphyric black rock doesn’t burn out your mind, if the shelleyphh doesn’t caused maddness, then you will at least end your term worshipping your boots and learn a’a swagger.”
  • Sure, I knew all about volcanic hazards! Just follow me, right?Well, I didn’t come here today to brag about how many craters I fell into, boots I destroyed, trucks I broke, and arguments I won against Frank Trusdell.I’m here to present the gritty results of the mapping on Mauna Loa and how that fieldwork translated into a useful hazard assessment.The boots-on-the-ground fieldwork led to a useful assessment of hazards on the northern flank of MLO.Volcanologists in the room? Ah, not so many… then I’ll just take a minute to explain the highlights of Mauna Loa.
  • After all that description, how can we improve on the Qualitative hazard zones?
  • I just wanted to map, map, map, map.Whereas Erika had insightful questions like: access? Area large enough to analyze? Enough geochemical variablility??
  • Built on the 1852 historical lava flowMauna Loa last erupted in 1984
  • Since we have now determined the connectivity of the lava…Assuming that any given area could be inundated in the future = use Poisson Analysis
  • Between a rock and a simulated space: Lava inundation probability

    1. 1. Between a rock and a simulated space:Lava inundation probabilityJames Madison UniversityGeology and Environmental ScienceSeminar Series 1/19/2013Julie A. Herrick
    2. 2. Intro To Volcanic Hazards October 1st, 2004
    3. 3. Precursory Activity
    4. 4. New Technologies
    5. 5. Communication
    7. 7. Primary Features of Big Island Volcanism Summit Crater Rift Zones: NE and SW Radial Vents: N flank Zonation: Red Yellow BlueModified from Lockwood, 1976
    8. 8. “Over the past 3,000 years ithas erupted lava flows, onaverage, every 6 years.Since 1843, Mauna Loa haserupted 33 times, averagingone eruption every 5 years.”~ USGS Fact Sheet „12
    9. 9. Mauna Loa Observatory (MLO) areaN
    10. 10. Mauna Loa Observatory (MLO) area Facility was operating in 1956350 m Barrier constructed in 1986 600 m
    11. 11. GOAL HAZARD assessment • Lava flow paths • Inundation zones • Inundation probabilityTOOLS • Detailed geological map (5.5 x 2.5 km) • DEM 10 m • 1984 topography BASIN VORISWHY? • NOAA MLO Hazard assessment • Isolated target (within our scope) • High vulnerability • Continued expansion of facilities
    12. 12. Mauna Loa Weather Observatory 1984 Moku’aweoweo Summit Crater NE Rift Zone Radial Vents  1956 Observatory established  1984: Flow from NERZ  Barrier construction in 1986S
    13. 13. Field Area: ~14 km2 • # Lava Flows: 41 • Radial Vents • Spatter Ramparts • Cinder Cones • North Pit Crater • Collapse Crater • Lava Tubes • Pahoehoe • A`a
    14. 14. Geological Map Qualitative data Quantitative data Spatial Distribution Zone Susceptibility + + DEM DEM Flow network Probability distributionBASIN VORIS Inundation zones • Flow simulation • Occurrence probability
    15. 15. BASINIvan 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
    16. 16. BASIN Analysis: Sensitivity Testing Threshold: CFA=cell flow accumulation Topography: good agreement Mapped channels: good agreementN FLOW NETWORK with CFA=400
    17. 17. 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
    18. 18. 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
    19. 19. Geographic Controls
    20. 20. Analysis #21. Each future eruption will occur independently (eg. will not berelated to the timing of previous eruptions).2. The probability that an eruption will occur in a future timeinterval will not change with the passage of time.3. The probability that an eruption will occur in a particular timeinterval is proportional only to the length of that interval.4. The probability of more than one eruption occurring in the sametime interval is very small.P = 100 (1 – e-t I T )(Lockwood and Hazlett, 2010; Davis 1986)
    21. 21. 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 ventsW N Pit crater E N Pit Crater
    22. 22. VORIS: theory and advantagesTopography 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
    23. 23. 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 sufficientTephra high Tephra high
    24. 24. NOAA MLO natural topographic protectionSOURCES • 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
    25. 25. 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 HWY200Easy to read inundation zones map + probability of lava inundation emergency defense plan long term land use planning
    26. 26. 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.
    27. 27. Lava Diversion Methods 1983 lava flows from Mount EtnaSapienza resort and tramway complex