12/26/2004 sumatra-andaman islands earthquake

12/26/2004 Sumatra-Andaman Islands Earthquake

• 3rd largest earthquake of the past 100 years (Mw 9.3).

• Generated historically large tsunamis that struck Indonesia, Thailand, Sri Lanka, India, Africa that killed approximately 300,000 people.

• No effective warning of tsunami due to lack of monitoring/communication system in the Indian Ocean

Seismograms of the day: Global Seismic Displacement Wavefield, December 26, 2004.

Earth Simulator Sumatra Surface Wave Simulation

c/o Jeroen Tromp

0S0 - 20.5 minutes

0S3 - 35.6 minutes

0S2 - 53.9 minutes

Spheroidal Normal Modes

Very Large Earthquakes Significantly Excite the Planet’s Normal Modes

The Sumatra-Andaman

rupture was significant, even on the scale of the

entire planet.

c/o Miaki Ishii

The Sumatra-Andaman rupture was complex and distributed over more than 7 minutes.

Global Moment Release (1906-2005)

Chile (1960)

Alaska (1964)

Sumatra (2004)

“Great” earthquake are very significant global events.

…seismic Momentis proportionalto fault areatimes fault slip

Global Moment Release (1906-2005)

Approximately half of all earthquake moment release on the planet over the past 100 years occurred in just three earthquakes (a manifestation of power law statistics)!

Physics of Water Waves

Waves are the response of a liquid to departures from gravitational equilibrium.

•Wind waves in the deep ocean: Wavelength << water depth

•Tsunami waves in the deep ocean: Wavelength >> water depth

Wind Waves (away from shore)

Tsunamis in the deep ocean

c/o Steve Ward

Global Tsunami Simulation