INDIAN OCEAN EARTHQUAKES AND TSUNAMIS

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INDIAN OCEAN EARTHQUAKES AND TSUNAMIS December
26, 2004 and March 28,2005
USGS field response
International Tsunami Survey Teams January, 2005
- Sri Lanka (2) January, 2005 - Sumatra
(1) March-April - Sumatra (6) United Nations
Environment Program Team February-March -
Maldives (1) USAID Coastal Zone Management Team
August - Sri Lanka (1) Supported by USGS,
OFDA, USAID
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Location of 26 December and 28 MarchEarthquakes
March 28, 2005 M 8.7
Dec 26, 2004 M 9.3
Modified from Kerry Sieh, CalTech
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USGS Tsunami Web Sites
USGS Tsunami Research http//walrus.wr.usgs.gov/
tsunami/ Tsunami Generation from the 2004 M 9.0
Sumatra Earthquake http//walrus.wr.usgs.gov/tsu
nami/sumatraEQ/ Initial findings from Sri Lanka
http//walrus.wr.usgs.gov/tsunami/indianocean.html
Initial findings from Sumatra (Jan. 20 - 29)
http//walrus.wr.usgs.gov/tsunami/sumatra05/ Initi
al findings from Sumatra (March 28 - April 26)
http//walrus.wr.usgs.gov/news/field.html

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West Sumatra International Tsunami Survey
Team (ITST2)
Leg 1 (30 March -12 April 2005) Gegar Prasetya
(BPPT)- Leg 1 Co-Leader Jose Borrero (USC)- Leg 1
Co-Leader Rahman Hidayat (BPPT) Bretwood Higman
(UW) Etienne Kingsley (USGS) Lukiyanto (BPPT)
Brian McAdoo (Vassar) Bob Peters
(USGS) Widjokongko (BPPT) Vasily Titov (NOAA PMEL)
Leg 2 (13 April -26 April 2005) Bruce Jaffe
(USGS)- Leg 2 Leader Lori Dengler (Humboldt
State) Guy Gelfenbaum (USGS) Bretwood Higman
(UW) Andy Moore (Kent State) Bob Morton
(USGS) Peter Ruggiero (USGS) Widjokongko
(BPPT) Eko Yulianto (LIPI)
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Data Collected During Surveys of26 December 2004
and 28 March 2005 Tsunamis

• Eyewitness Reports
• Water Levels
• Flow Directions
• Water and Sand Inundation
• Bathymetry and topography profiles
• Subsidence/Uplift
• Coastal Morphology and Response
• Sediment deposit profiles

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Need for rapid post-tsunami investigations
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Need for rapid post-tsunami investigations
January 22, 2005
April 17, 2005
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RV Seimoa
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Water Level Indicators
Tsunami Water Level
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Water Level Indicators in Trees
Stripped bark
Broken branch
Debris pile
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ITST 1 Tsuji et al
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ITST 2 sites surveyed

• 13 topographic profiles
• water levels, water depths, runup
• 9 detailed sediment transects
• 100s sediment samples for grain-size analysis
• 5 bathymetric surveys

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Topographic Profiles
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Nearshore Bathymetric Mapping
Monitor w/ navigation
GPS antenna
echo sounder
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Jantang Bathymetry
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Jantang Topographic Profiles
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Jantang
Erosion zone
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Langi
Wave direction
Return flow
Return flow (dominant)
N
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Tsunami Flow Direction
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Tsunami Deposits
tsunami sand
buried soil

• marine sand over soil
• thickness varies 0-70 cm
• often normal grading
• multiple pulses of sedimentation

fine sand
coarse sand
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Photo of making a peel
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Kuala Meurisi
water levels
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Beach Resort Profile
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Simeulue Island - Busung Bay
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Past Tsunamis Impacting Indonesia (ITDB)
Significant historical tsunamis
YEAR LOCATION HEIGHT VICTIM
1797 Padang ? 300
1833 W. Sumatra gt 4 m ?
1843 Nias Island many fatalities many fatalities
1861 W. Sumatra gt 6 m 725
1883 Java Sumatra 38 m 36,500
YEAR LOCATION HEIGHT VICTIM
1907 Simeulue Island ? 1700
1992 Flores 25 m 2000
1994 Banyuwangi 15 m 200
2004 Aceh 33 m 200,000
2005 Nias 4 m 0
Modified from ITDB and George Pararas-Carayannis
(http//wwww.drgeorgepc.com/Tsunami2005ndonesia.ht
ml)
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Searching for paleotsunami deposits
Outcrop observation
Coring
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Palaeotsunami Record Lhok Leumpung (Calang)
Dec 26 tsunami deposit
Soil
1907 tsunami deposit ?
Soil
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Palaeotsunami Record Busung Bay Simeulue Island
Dec 26 March 28 tsunami deposit
Soil
1907 tsunami deposit ?
Soil
Sand
Soil
Sand
Soil
Sand coral
Soil
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Coastal Change
29 Dec 2004
10 Jan 2003
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Subsidence (1-2 m)
after earthquake
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Pre-tsunami
road
Immediate post-tsunami
1-1.5 m subsidence
road
Rapid erosion No beach
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April 17, 2005
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sandy beach re-forming
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Coastal uplift
1.1 m above hwl
Coral platform
Oyster colony
Mangrove forest
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Asu Island, offshore Sumatra
http//walrus.wr.usgs.gov/news/field.html
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ICESat Determines Sumatra Earthquake Uplift
a Bathymetry and topography of the
Sumatra-Andaman arc, epicenter of December, 2004
M9 earthquake (star), and subduction zone 1500 km
rupture length (red), b ICESat ground tracks
(orange) on color-coded topography of the Andaman
Islands from SRTM, c enlargement of Sentinel
Island, d Landsat 7 Thematic Mapper
natural-color image of Sentinel Island showing
fringing coral reef (white) elevated above
sea-level by the earthquake, and e oblique
photo of the elevated coral reef and vegetation
cover on the island interior. POC David Harding,
NASA GSFC, Code 698
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Sentinel Island Uplift Approximately 2 m
a ICESat footprint locations (Release 19) for
Oct. 22, 2003 (red) and Feb. 24, 2005 (white),
with a 50 m cross-track distance between
profiles, on western Sentinel Island displayed as
color-coded topography from SRTM, and b
waveform-derived elevation profiles showing coral
reefs elevated 1 m above the ocean surface and
2 m uplift of the flat shorelines, where bare
and vegetation covered uplift in the island
interior is not apparent, probably because the
2005 profile is slightly down-slope from the 2003
profile causing a downward offset of several
meters. Saturation of reef and un-vegetated
shoreline waveforms precludes determination of
centroids and signal ends. Two repeat profiles
across the larger islands of the Andaman chain
will be acquired in March. POC David Harding,
NASA GSFC, Code 698
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Busung, Simelue Is. 12/26/04 - 0.5 m subsidence
3.2 m tsunami 3/28/05 - 1.5 m
uplift Gusung Bay, Simelue Island 3/28/05 -
1.5 m uplift 4.2 m tsunami
Salaut Island 12/26/04 - 2 m uplift
4-5 m tsunami 3/28/05 - 2m gt tsunami
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Sites Surveyed by ITST2
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Top priority Save Peoples Lives
Risk mitigation In Aceh Province from a Tsunami
Warning System on December 26 would have been
limited

• Not enough time between earthquake and tsunami to
  disseminate warnings
• 2) Some remote areas may have limited ability to
  receive warnings

Education is the main tool for saving lives in
the near source area
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Comparing what happened in Jantang and Langi
Langi
Jantang
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Jantang

• Water height 15 - 20 m
• 100 structures destroyed
• Few people survived
• No previous awareness of tsunamis

Current activities removing debris, gathering
coconuts, reclaiming family land
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Langi, Simuelue

• Water height gt10 m
• Many structures destroyed
• 100 of population survived
• Oral history of 1907 tsunami - smong

Current activities building boats, gardening,
fishing Still dependent upon aid but normal
village life has resumed
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Mitigation of the risk from locally generated
tsunamis

• The earthquake is the warning
• Long-term planning is essential
• Education is the tool
• Individuals must know what to do

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Using Coastal Geology to Reduce Tsunami Risk

• Generate maps of past tsunami erosion,
  deposition, and inundation
• Generate maps of tsunami hazard risk zones
• Incorporate in long-range coastal planning
  (evacuation routes, location of public buildings)
• Increase public awareness and education

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Incorporating Geologic Information into Tsunami
Mitigation Planning

• Geologic record of tsunami magnitude and
  frequency
• Factors influencing tsunami impacts (tsunami
  characteristics, topo-bathy, shore type, density
  and type of development)
• Site analysis (integrate with inundation modeling)

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Probabilistic Tsunami Hazard Assessmentthe
Seaside, Oregon Pilot Study
Probabilities Modeling Impacts
Co-operative Study NOAA USGS USC PSU METU OTHERS
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Seaside, OR Tsunami Pilot Study
Courtesy of Frank Gonzalez, NOAA