At 00:58:53 UTC on 26 December 2004,

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(No Transcript)
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At 005853 UTC on 26 December 2004, Great
earthquake off northeast coast of Sumatra,
Indonesia.
Location map of Indonesia from the National
Earthquake Information Center (http//neic.usgs.go
v/neis/bulletin/neic_slav_l.html)
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Earthquake caused by subduction of Indian plate
beneath the Burma microplate
Relative motion of Indian plate to Burma
microplate 0.06 m per year (2.4 inches per year)
Other tectonic elements in region Yangtze
Plate Eurasia Plate Sunda Trench Sunda
Plate Australian Plate Ninety East Ridge
Tectonic Setting of Earthquake of 26 December
2004 from United States Geological
Survey (http//earthquake.usgs.gov/eqinthenews/200
4/usslav/)
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Mw 9.0 Hypocenter 30 km depth Focal
mechanism thrust Largest quake since 1964 Good
Friday event, Alaska Large magnitude quakes at
subduction zones are often tsunamigenic Local
tsunamis propagate toward nearest
shoreline Teletsunamis spread out across ocean
basins
Map showing epicenter (star) of earthquake from
the National Earthquake Information
Center (http//neic.usgs.gov/neis/bulletin/neic_sl
av_l.html)
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Seismicity 1900-2004 Star is 26 Dec 2004
event Well-defined Benioff Zone associated with
subduction of Indian plate beneath Burmas
microplate Thus, main event occurred in
seismically active area Many earthquakes
annually Many have Mw gt 6.5 (damaging magnitudes)
Map showing historical seismicity (1900 - 2004)
from the National Earthquake Information
Center(http//neic.usgs.gov/neis/bulletin/neic_sl
av_l.html)
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Est. rupture length 1200 km Est. rupture width
100 km Est. thrust fault offset 15m Est.
seafloor uplift m? Uplift of seafloor is
responsible for excitation of tsunamis
Map showing historical seismicity (1900 - 2004)
from the National Earthquake Information
Center(http//neic.usgs.gov/neis/bulletin/neic_sl
av_l.html)
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Areas potentially affected by tsunami inundation
and run-up in yellow (i.e. shore zones lt 20 m
above sea-level)
Areas Potentially Affected by Tsunami of 26
December 2004 from UNOSAT(www.unosat.org)
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Areas potentially affected by tsunami inundation
and run-up in red
Map showing areas potentially inundated by
tsunami on 26 December 2004 from
UNOSAT.(http//cern.ch/unosat/freeproducts/Tsunam
i/JRC/Asia_Tsunami_07January_landcover.pdf)
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Potential population affected by tsunami in red
zone
Potential population affected by tsunami on 26
December 2004 from UNOSAT(http//cern.ch/unosat/f
reeproducts/Tsunami/JRC/Asia_Tsunami_04January.pdf
)
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Predicted Arrival Time of First Tsunami Wave (in
hours after earthquake)
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Numerical simulation (computer model) of tsunami
Dr. A. Piatanesi of the National Institute of
Geophysics and Volcanology (INGV) in Rome, Italy.
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Animation of Before and After Images of Banda
Aceh, Indonesia
Animation produced at the Earth Visualization
Laboratory, University of Arkansas, USA By Dr.
Stephen K. Boss
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Countries Reporting Direct Casualties from
Earthquake and Tsunami Indonesia Thailand Andaman
Islands (India) Nicobar Islands
(India) Myanmar Bangladesh India Sri Lanka The
Maldives The Seychelles Kenya Somalia Tanzania In
addition, many western nations are reporting
fatalities and missing among tourists who were
visiting the affected countries
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Fundamental Features of Water Waves
Wave Crest is the highest portion of the
wave. Wave Trough is the lowest portion of the
wave. Wavelength is the linear distance
separating wave crests (or separating wave
troughs). Wave Amplitude is the displacement of
a crest or trough about the mean position or
water level. Wave Height is the total vertical
distance from crest to trough (equal to twice the
amplitude). Wave Period is the time required for
successive wave crests (or troughs) to pass a
fixed point.
from An Introduction to the World's Oceans, 8th
edition by K.A. Sverdrup, A.C. Duxbury, and A.B.
Duxbury (2004)
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deep-water waves water depth is greater than
one-half the waves' length. shallow-water
waves depth becomes shallower than 1/20th of the
wavelength
Tsunamis have wavelengths ranging from 100 200
km! Tsunamis are, therefore, shallow-water waves
(even in the open ocean)! Though tsunamis have
very long wavelengths, their amplitude in the
open ocean is often relatively small - commonly
only a meter or two - and this amplitude is
distributed over the very long wavelength so that
tsunamis are quite imperceptible on the surface
of the ocean. The speed of tsunamis is called
celerity and is equal to 3.31 x D0.5, where D
water depth (in meters) In the deep ocean,
tsunamis travel at speeds up to 750 km per hour
(465 mi/hr)!
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Wave Refraction occurs when waves enter shallow
water over an irregular bottom Wave traveling in
shallowest water will also move with the slowest
celerity Waves in deeper water continue moving
with relatively greater celerity Wave crests
will curve or refract as the wave moves forward
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Waves spread or disperse upon passing through the
gaps in barriers. This process is called "wave
diffraction Barriers with many gaps scatter
wave energy, diminish wave height and power
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Numerical simulation (computer model) of tsunami
Dr. A. Piatanesi of the National Institute of
Geophysics and Volcanology (INGV) in Rome, Italy.
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Tsunamis are waves generated by displacement of
the ocean by impulsive events Events known to
generate tsunamis Submarine earthquakes Explosi
ve volcanic eruptions Submarine
landslides Terrestrial landslides that enter
water bodies Impacts of large extraterrestrial
objects (e.g. asteroids or comets) in the ocean
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Tsunami Triggered by Submarine Earthquake (other
than 26 December 2004) The Great Chilean
Earthquake and Tsunami, 1960 (largest earthquake
ever recorded, Mw 9.5) Tsunamis devastated
Pacific Rim (Chile, Hawaii, Japan) Good Friday
Earthquake, Anchorage, Alaska, 1964 (also an Mw
9.2 earthquake) Tsunamis devastated coastal
Alaskan communities Tsunami also devastated
Crescent City, California
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Tsunami Triggered by Explosive Volcanic
Eruption Krakatau, Indonesia, 1883 On 26-27
August 1883, Krakatau volcano erupted Among most
violent volcanic eruptions in last 200
years Tsunamis triggered by volcanic explosion
and caldera collapse Destroyed 165 coastal
Indonesian villages on Java and Sumatra 36,000
Fatalities Prior to 26 December 2004, most
destructive tsunamis on record
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Tsunami Triggered by Submarine Landslides Storreg
a, Norway Series of submarine slides at ca.
35,000 and ca. 7,000 years ago Triggered by
earthquake or decomposition of gas hydrate in
seafloor sediment Storegga 1 (30,000-35,000
years before present) Storegga 2(approximately
7,000 years before present) Storegga
3(approximately 7,000 years before
present) Largest mass movement affecting the
northwest European continental margin in the
last 50,000 years Tsunami deposited sediment
widespread on Scottish coast
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Tsunami Triggered by Terrestrial Landslide that
Entered Water Body Lituya Bay, Alaska 9 July
1958 Large earthquake created massive rock
avalanche into fjord in southeast
Alaska Resulting impulsive wave is the highest
ever recorded 525 m (over 1,700 ft) Several
eyewitnesses lived to tell about it!
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Tsunami Triggered by Impacts of Large
Extraterrestrial Objects Chicxulub,
Mexico Asteroid impact site and tsunami trigger
terminating the Cretaceous Period Asteroid
believed to have had 10 km diameter (6.2
miles) Impact in shallow tropical seas Tsunami
deposits widespread across Caribbean basin Gulf
of Mexico Impact event also associated with mass
extinction of terrestrial and marine biota
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The Andaman-Nicobar Earthquake and Tsunamis are
possibly the greatest natural disasters in human
history. At this time, worldwide relief efforts
are underway as all nations attempt to provide
comfort and aid to tsunami and earthquake
survivors while also accounting for those who
forever washed away. Individuals interested in
contributing to tsunami relief efforts are
encouraged to contact reputable humanitarian
agencies.