Transcript Great Earthquake and Tsunami of 2004

Great Earthquake and Tsunami of 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)
Great Earthquake and Tsunami of 26 December 2004
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/2004/usslav/)
Great Earthquake and Tsunami of 26 December 2004
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_slav_l.html)
Great Earthquake and Tsunami of 26 December 2004
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)
Great Earthquake and Tsunami of 26 December 2004
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_slav_l.html)
Great Earthquake and Tsunami of 26 December 2004
Areas 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 2004
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/Tsunami/JRC/Asia_Tsunami_07January_landcover.pdf)
Great Earthquake and Tsunami of 26 December 2004
Potential population affected by tsunami in red zone
Potential population affected by tsunami on 26 December 2004 from UNOSAT
(http://cern.ch/unosat/freeproducts/Tsunami/JRC/Asia_Tsunami_04January.pdf)
Great Earthquake and Tsunami of 26 December 2004
Predicted Arrival Time of First Tsunami Wave (in hours after earthquake)
Great Earthquake and Tsunami of 26 December 2004
Great Earthquake and Tsunami of 26 December 2004
Numerical simulation (computer model) of tsunami
Dr. A. Piatanesi of the National Institute of Geophysics and Volcanology (INGV) in Rome, Italy.
Great Earthquake and Tsunami of 26 December 2004
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
Great Earthquake and Tsunami of 26 December 2004
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
Great Earthquake and Tsunami of 26 December 2004
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)
Great Earthquake and Tsunami of 26 December 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)!
Great Earthquake and Tsunami of 26 December 2004
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
Great Earthquake and Tsunami of 26 December 2004
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
Great Earthquake and Tsunami of 26 December 2004
Numerical simulation (computer model) of tsunami
Dr. A. Piatanesi of the National Institute of Geophysics and Volcanology (INGV) in Rome, Italy.
Great Earthquake and Tsunami of 26 December 2004
Tsunamis are waves generated by displacement of the ocean by impulsive events
Events known to generate tsunamis:
Submarine earthquakes
Explosive volcanic eruptions
Submarine landslides
Terrestrial landslides that enter water bodies
Impacts of large extraterrestrial objects (e.g. asteroids or comets) in the ocean
Great Earthquake and Tsunami of 26 December 2004
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
Great Earthquake and Tsunami of 26 December 2004
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
Great Earthquake and Tsunami of 26 December 2004
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
Great Earthquake and Tsunami of 26 December 2004
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!
Great Earthquake and Tsunami of 26 December 2004
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
Great Earthquake and Tsunami of 26 December 2004
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.