INDIAN OCEAN BOTTOM PROFIL

EPICENTER

TSUNAMI COASTAL AMPLITUDES

TSUNAMI 2004 ANIMATION

NOAA

NOAA ANIMATION SHOWS WORLDWIDE REACH OF INDIAN OCEAN TSUNAMI

The massive tsunami triggered by an undersea earthquake in the Indian Ocean literally rippled around the world. NOAA scientist Vasily Titov, using seismic data, rendered an animation showing how the tsunami waves propagated across the Earth. Some of the waves reached the United States and many other nations outside the Indian Ocean.

NOAA screen capture of Indian Ocean tsunami propagating across the world.

Click NOAA screen capture for larger view of tsunami worldwide propagation. Click here for high resolution version. Please credit "NOAA."

Titov used the numerical model called Method of Splitting Tsunami, or MOST. He used this model hours after the tsunami first struck showing the quake’s epicenter and how the tsunami moved across the Indian Ocean.

The animation covers a period of 44 hours and 27 minutes of tsunami propagation. The tsunami reached the Atlantic and Pacific coasts of the United States about the same time—some 28 hours after the earthquake struck on Dec. 26, 2004, at 00.59 UTC or 7:59 p.m. EST. The MOST model also was used to interpret the data for the tsunami's wave height from four satellites.

Please credit “NOAA” in your Chyron or in print.

Please note: "Right-click" the links below to download the very large files.

MPG || AVI || MOV

NOAA Tsunami Research

 http://www.noaanews.noaa.gov/stories2005/s2365.htm

SATAKE

PRE DISASTER SEISMICITY: NE IO REGION

AFTERSHOCKS

Map showing earthquake activity in the vicinity of the Java Trench around the time of the 2004 Indian Ocean earthquake. Prepared by the USGS/NEIC

SUNDA TRENCH AND SUBDUCTION ZONE

Sunda Trench

From Wikipedia

Map showing earthquake activity in the vicinity of the Java Trench around the time of the 2004 Indian Ocean earthquake. Prepared by the United States Geological Survey

The Sunda Trench, earlier known as, and sometimes still indicated as the Java Trench,^[1] is located in the northeastern Indian Ocean, with a length of 3,200 kilometres (2,000 mi).^[2] The maximum depth of 7,725 metres (25,344 ft) (at 10°19'S, 109°58'E, about 320 km south of Yogyakarta), is the deepest point in the Indian Ocean. The trench stretches from the Lesser Sunda Islands past Java, around the southern coast of Sumatra on to the Andaman Islands, and forms the boundary between Indo-Australian Plate and Eurasian plate (more specifically, Sunda Plate). The trench is considered to be part of the Pacific Ring of Fire as well as one of a ring of oceanic trenches around the northern edges of the Australian Plate.
There is scientific evidence that the 2004 earthquake activity in the area of the Java Trench could lead to further catastrophic shifting within a relatively short period of time, perhaps less than a decade.^[3] This threat has resulted in international agreements to establish a tsunami warning system in place along the Indian Ocean coast.^[4]

Characteristics

For about half its length, off of Sumatra, it is divided into two parallel troughs by an underwater ridge, and much of the trench is at least partially filled with sediments. Mappings after the 2004 Indian Ocean earthquake of the plate boundary showed resemblance to suspension bridge cables, with peaks and sags, indicative of asperity and locked faults, instead of the traditional wedge shape expected.^[5]

Exploration

Some of the earliest exploration of the Trench occurred in the late 1950s when Robert Fisher, Research Geologist at the Scripps Institution of Oceanography, investigated the trench as part of a worldwide scientific field exploration of the world's ocean floor and sub-oceanic crustal-structure. Bomb-sounding, echo-train analysis and manometer were some of the techniques used to determine the depth of the trench. The research contributed to an understanding of the subduction characteristic of the Pacific margins.^[6]
Various agencies have explored the trench in the aftermath of the 2004 earthquake, and these explorations have revealed extensive changes in the ocean floor.^[7]

Associated seismicity

The subduction of the Indo-Australian Plate beneath a bloc of the Eurasian Plate is associated with numerous earthquakes. Several of these earthquakes are notable for their size, associated tsunamis, and/or the number of fatalities they caused.

Sumatra segment

• 1797 Sumatra earthquake: Magnitude ~8.4
• 1833 Sumatra earthquake: Magnitude 8.8–9.2
• 1861 Sumatra earthquake: Magnitude ~8.5
• 1935 Sumatra earthquake: Magnitude 7.7
• 2000 Sumatra earthquake: Magnitude 7.9
• 2002 Sumatra earthquake: A Magnitude 7.3 earthquake that occurred at the boundary between the rupture areas of the 2004 and 2005 earthquakes listed below.
• 2004 Indian Ocean earthquake and tsunami: Mw 9.1–9.3
• 2005 Sumatra earthquake: Magnitude 8.6
• September 2007 Sumatra earthquakes: Series of earthquakes, the three largest were magnitude 8.5, 7.9 and 7.0.
• 2009 Sumatra earthquakes: Magnitude 7.9
• October 2010 Sumatra earthquake and tsunami: Magnitude 7.7

Java segment

• 1917 Bali earthquake: Magnitude 6.6
• 1994 Java earthquake: Magnitude 7.8
• 2006 Pangandaran earthquake and tsunami: Magnitude 7.7
• 2009 West Java earthquake: Magnitude 7.0

References

                

1.·  Sunda Trench (4°30' S 11°10' S 100°00' E 119°00' Accredited by: SCGN (Apr. 1987) The trench was studied in some detail in 1920's-1930's by Dutch geodesist F.A. Vening Meinesz, who made classic pendulum gravity measurements in a Dutch submarine. Shown as Java Trench in ACUF (Advisory Committee on Undersea Features Gazetteer). see also: http://www.gebco.net/

2.·  ·  Java Trench - article from Encylopedia Britannica

3.·  ·  Asia primed for next big quake - earth - 19 March 2005 - New Scientist Environment

4.·  ·  IOC: Towards a Tsunami Warning System in the Indian Ocean

5.·  ·  Physorg:Folded sediment unusual in Sumatran Tsunami area

6.·  ·  http://web.archive.org/web/20060430125347/http://www.ngdc.noaa.gov/mgg/gebco/news/rlfnews.pdf

7.    ·  "The underwater survey of the SUMATRA earthquake source area"

Further reading

• Špičák, A., V. Hanuš, and J. Vaněk (2007), Earthquake occurrence along the Java trench in front of the onset of the Wadati-Benioff zone: Beginning of a new subduction cycle?, Tectonics, 26, TC1005 (This page was last modified on 3 April 2016, at 19:05).

FIGURE:  The faults around Sumatra and the Sunda trench.

From the following article:

Seismology:  Earthquake risk on the Sunda trench

Suleyman S. Nalbant, Sandy Steacy, Kerry Sieh, Danny Natawidjaja and John McCloskey

Nature 435, 756-757(9 June 2005)

doi:10.1038/nature435756a

a, Schematic of the Sumatran subduction zones with the overlying plates removed. Calculated three-dimensional stresses, including contributions from both earthquakes resolved directly on to the structures of interest, have been projected on to a diagram of the structural geometry and geography of the region. Here we use a low-value coefficient of effective friction, 0.4, although the main results are robust to large ranges of this value. Grey-scale values on the rupture plane represent the amount of slip in metres experienced on the southernmost 450 km of the Sumatra–Andaman earthquake and on the Simeulue–Nias earthquake. Colour-scale values represent the co-seismic stress change on the Sunda-trench subduction zone and the Sumatra fault. Stress contours are in 2-bar intervals. Red dashed contours indicate zero co-seismic stress. Black star indicates the location of Banda Aceh. b, Locations of ruptures of recent and historical earthquakes on the Sunda trench. Dotted lines indicate approximate extents of historical ruptures (1833, 1861 and 1935); solid lines surrounding dark-blue areas indicate seismological inversions of recent earthquakes; red star, epicentre of December 2004 event; yellow star, epicentre of March 2005 event; black star, Banda Aceh. The rupture area of the 1797 event, which is not shown here, probably overlaps significantly with the 1833 event under Sipura and Pagai Islands and may extend under Siberut Island. The precise extent of this event strongly influences the estimated slip deficit on the megathrust. (nature.com)


The Earth’s solid surface floats on a layer of softer rock as a collection of interlocking, movable puzzle pieces called tectonic plates. At 7:58 a.m. (local time), on December 26, 2004, beneath the Indian Ocean west of Sumatra, Indonesia, pent-up energy from the compressional forces of one tectonic plate grinding under another found a weak spot in the overlying rock. The rock was thrust upward, and the Earth shook as a 9.0 magnitude earthquake sent its vibrations out into the ocean. Tsunamis spread out in all directions; the massive waves washed over islands and crashed against coastlines in Sri Lanka, Southern India, and even the east coast of Africa. Tens of thousands of people were killed; millions are homeless.
The image above shows how the tectonic puzzle pieces fit together around Indonesia. The epicenter of the recent quake is marked with a red star in the image. It is located just to the east of the Sunda Trench, where the India Plate begins to get subducted beneath (forced under) the Burma Plate. The blue arrows along the plate boundary show the direction of subduction.
As the India Plate slides beneath the Burma Plate, it meets pockets of resistance, which causes compressional forces to build up. Weakened overlying rock gets forced upward. Based on the location of aftershocks (red shaded circles on the image), the United States Geological Survey reports that approximately 1,200 kilometers of the plate boundary probably slipped as a result of the quake. The initial rupture was likely more than 100 kilometers wide, and probably produced an average vertical displacement along the fault plane (the slope along which the two plates meet) of 15 meters.
When the bottom of the ocean is deformed by this type of “megathrust” quake, the upward force acts like a fist rising up from underwater. Water rolls down off the sides of the “fist,” creating massive waves that can travel as fast as an airplane. The waves can move across the ocean and barely disturb the surface, but when they reach shallow coastal water, the earthquake’s energy thrusts them tens of meters into the air. The tsunami created by this earthquake reached India and Sri Lanka in about four hours. The wave eventually reached Africa, the Pacific Ocean, Hawaii, and the west coast of North and South America.
For more information about this earthquake and plate tectonics, visit the Website of the USGS.

Image courtesy United States Geological Survey