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

Great Earthquake and Tsunami of 26 December 2004


At 00:58:53 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.gov/neis/bulletin/neic_slav_l.html)


Tectonic Setting of Earthquake of 26 December 2004 from United States Geological Survey(http://earthquake.usgs.gov/eqinthenews/2004/usslav/)

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 PlateEurasia PlateSunda TrenchSunda PlateAustralian PlateNinety East Ridge


Map showing epicenter (star) of earthquake from the National Earthquake Information Center(http://neic.usgs.gov/neis/bulletin/neic_slav_l.html)

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 historical seismicity (1900 - 2004) from the National Earthquake Information Center(http://neic.usgs.gov/neis/bulletin/neic_slav_l.html)

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 > 6.5 (damaging magnitudes)


Map showing historical seismicity (1900 - 2004) from the National Earthquake Information Center(http://neic.usgs.gov/neis/bulletin/neic_slav_l.html)

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

Great Earthquake and Tsunami of 26 December 2004Areas potentially affected by tsunami inundation and run-up in yellow

(i.e. shore zones < 20 m above sea-level)

Areas Potentially Affected by Tsunami of 26 December 2004 from UNOSAT(www.unosat.org)

Great Earthquake and Tsunami of 26 December 2004Areas 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/Tsunami/JRC/Asia_Tsunami_07January_landcover.pdf)


Potential population affected by tsunami on 26 December 2004 from UNOSAT(http://cern.ch/unosat/freeproducts/Tsunami/JRC/Asia_Tsunami_04January.pdf)

Potential population affected by tsunami in red zone

Great Earthquake and Tsunami of 26 December 2004Predicted Arrival Time of First Tsunami Wave (in hours after earthquake)



Numerical simulation (computer model) of tsunami Dr. A. Piatanesi of the National Institute of Geophysics and Volcanology (INGV) in Rome, Italy.


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


Countries Reporting Direct Casualties from Earthquake and Tsunami

IndonesiaThailand

Andaman Islands (India)Nicobar Islands (India)

MyanmarBangladesh

IndiaSri Lanka

The MaldivesThe Seychelles

KenyaSomaliaTanzania

In addition, many western nations are reporting fatalities and missing among tourists who were visiting the affected countries


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)


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)!


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


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


Numerical simulation (computer model) of tsunami Dr. A. Piatanesi of the National Institute of Geophysics and Volcanology (INGV) in Rome, Italy.


Tsunamis are waves generated by displacement of the ocean by impulsive events

Events known to generate tsunamis:

Submarine earthquakesExplosive volcanic eruptions

Submarine landslidesTerrestrial landslides that enter water bodies

Impacts of large extraterrestrial objects (e.g. asteroids or comets) in the ocean


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 communitiesTsunami also devastated Crescent City, California


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


Tsunami Triggered by Submarine Landslides

Storrega, 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


Tsunami Triggered by Terrestrial Landslide that Entered Water Body

Lituya Bay, Alaska9 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!


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


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.Individuals interested in contributing to tsunami relief efforts are encouraged to contact reputable humanitarian agencies.

Documents

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