December 26, 2004

The Sumatra Earthquake &

TsunamiNick D’Anna

Plainedge Schools

Great Wave off the Coast of Kanagawa, by HokusaiThis print is somewhat misleading in that tsunamis

do not always manifest themselves as the huge breaking waves.

What is a tsunami?

• From the Japanese word tsunami meaning "harbor wave“

• Often mistakenly called "tidal waves“.

• They have nothing to do with tidal action.

• Seismic sea waves caused by earthquakes, submarine landslides, and, infrequently, by eruptions of island volcanoes.

Deep Earthquakes occur at subduction zones

Tsunami waves are sent outradially from the point of thrust. A tsunami wave can travel enormous distances. The Dec. 26th tsunami eventually made its way to the pacific ocean and noticeably affected the sea on the west coast of the US.

• Most tsunamis do not result in giant breaking waves.

• Rather, they come in much like very strong and very fast tides (i.e., a rapid, local rise in

sea level). • Much of the damage inflicted by tsunamis is

caused by strong currents and floating debris.

The Facts about December 26th

A great earthquake occurred at 00:58:50 (UTC), at 6:58 a.m. local time, on Sunday, 26 December 2004. The magnitude 9.0 event was located off the West coast of Northern Sumatra.

This is the fourth largest earthquake in the world since 1900 and is the largest since the 1964 Prince William Sound, Alaska earthquake. The earthquake had a depth of 10 km

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Page 5 of your ESRT

At Sumatra, the Indian plate was

subducted beneath the overriding

Burma plate. The Indian plate begins its decent into the

mantle at the Sundra trench

(west of the epicenter). The

relative motion of the two plates has

been 6cm/yr. Image curtsey of Eric Cohen

Historical Seismic Activity

Past Tsunamis

Indian Ocean

Tsunami Natl. Inst.

of Advanced Industrial Science &

Technology

A section of the northern shore of Aceh, Sumatra, Indonesia, pre- and post-tsunami

(by Digital Globe)

A section of the northern shore of Aceh, Sumatra, Indonesia, pre- and post-tsunami

(by Digital Globe)

A section of the northern shore of Aceh, Sumatra, Indonesia, pre- and post-tsunami

(by Digital Globe)

Tsunami Warning Systems do exist. Unfortunately, there was no such

system in place among the nations around the Indian Ocean. Within

15 minutes of the megaquake, officials from the PTWC were

calling nations in danger to warn them. The information was slow to get to the locations in greatest risk.

Tsunami Warnings

There are currently two tsunami warning centers for Canada and the US:

1. The West Coast / Alaskan Tsunami Warning Center (WC/ATWC)

2. The Pacific Tsunami Warning Center (PTWC)

• Seismographs record Earthquake activity world wide.

• Buoys in the ocean send signals to satellites about the level of the sea surface.

• That information is sent to the Tsunami warning centers which in turn make decisions about weather to issue a warning.

• If a warning is issued, there are a few ways to notify the public.

• Locally, sirens are used.

• For distant tsunamis, NOAA radio stations notify the public

• The best immediate response is to head for higher ground.

• Locations within 1 mile of the coast and at elevations lower than 100 ft are at the greatest risk.

Amateur video of the tsunami

A Sri Lanka resort

Another Sri Lanka resort

Phuket resort, Thailand

Patong beach, Thailand

Penang beach, Malaysia

Links for more information on this event• www.NYTimes.com• USGS Sundra Trench Earthquake and Aftershock Map

at http://www.oceansonline.com/sunda_trench_earthquake.pdf

• Tectonic Summary of Sumatra Earthquake, http://www.oceansonline.com/Tectonic%20Summary%20USGS.pdf

• 2004 Indian Ocean Earthquake graphic http://www.oceansonline.com/images/745px-Harta_Ocean_Indian_Quake.png

• Tsunami Great Waves, http://www.oceansonline.com/great_waves_en_2002.pdf

• Dr. C’s Remarkable Ocean World http://www.oceansonline.com/tsunami2004.htm

References

• Most of the diagrams and images from this PowerPoint come from GlobalSecurity.org at http://www.globalsecurity.org/eye/andaman-ani.htm

• The video clips are courtesy of Steve Kluge, Earth Science Teacher.