A magnitude 9.0 megathrust earthquake occurred on December 26, 2004 just off the coast of Sumatra, Indonesia. The earthquake happened on the interface of the India and Burma plates. Based on preliminary locations of larger aftershocks, approximately 1200 kilometers of the plate boundary slipped as a result of the earthquake. From the size of the earthquake it is likely that average displacement on the fault plane was about 15 meters.

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Science magazine Special Issue: The Great Sumatra-Andaman Earthquake

The following figures help to illustrate the science of seismology and plate tectonics. Click on the small image to get a larger image and full caption.


Normal modes show that the December 26, 2004 Sumatra earthquake was even bigger than previously thought. Analysis of the longest period normal modes of the earth, 0S2 and 0S3, yields a moment of 1.3e30 dyn-cm, approximately three times larger than the 4e29 dyn-cm measured from long period surface waves. (More...)

Epicenters of the December 26, 2004, northern Sumatra earthquake and its large aftershocks are plotted as stars. The Harvard CMT (Centroid Moment Tensor) solutions are plotted as beach-balls, which indicate mode of earthquake faulting. (More...)

Cumulative seismic moment of earthquakes in the Harvard CMT catalog since 1976. (More...)

GSN Waveforms

This record section plot displays vertical displacements of the Earth's surface recorded by the IRIS GSN stations. (More...)

A map of the GSN stations is helpful for locating the stations used in this figure.


Global map showing the location of GSN stations in the above waveform plot and great circle paths between the stations and the Sumatra-Andaman Earthquake. (More...)

Similar to the plot above, this record section plot also displays vertical displacements of the Earth's surface recorded by the EarthScope USArray stations. (More...)

A map of the GSN stations is helpful for locating the stations used in this figure.


The first day’s recording at station PALK (distance 14 degrees) beginning one hour after the main earthquake occurred and filtered to display waves of period longer than 200 seconds. (More...)

The same recording at station PALK but filtered to emphasize waves of period shorter than one second. (More...)

Broadband seismometers recorded ground motions from the Sumatran earthquake "on  scale" at locations worldwide. (More...)

The spectrum of a P wave follows a characteristic shape, with a low-frequency plateau and a high-frequency rolloff. (More...)

The Sumatra earthquake was recorded by the first of five NSF-funded long-baseline tiltmeters in Washington State designed to monitor slow earthquakes associated with deep subduction zone activity. (More...)

This figure shows the path of the tilt vector with the time indicated at approximately 1 minute increments. (More...)

At longest periods, the 2004 Sumatra-Andaman earthquake rang Earth like a bell, and the planet is still ringing. (More...)

Periodically-triggered seismic events at Mt. Wrangell Volcano, Alaska following the Sumatra-Andaman Islands earthquake. (More...)

This plot shows the accelerations observed at IRIS/IDA stations COCO (Cocos Keeling Island) and PALK (Pallekele, Sri Lanka) during the 12/26/04 Sumatran earthquake. (More...)

As the Earth is a finite body, there is a series of arrivals of different seismic phases that constructively and destructively interfere after propagating around the Earth, such that only certain frequencies will resonate over long time intervals. (More...)

This movie illustrates simulation of seismic wave propagation generated by
Dec. 26 Sumatra earthquake.
(More...)

Horizontally-polarized (SH) shear displacement wavefield recorded at a subset of GSN stations (54 - 72 degrees epicentral distance), plotted along zimuths from the epicenter. (More...)

Seismograms recorded by a prototype optical fiber seismometer in an IGPP laboratory at SIO and an STS-2 at the ANZA seismographic station SOL about 3 km away. (More...)

Sections of the seismograms from the above figure. (More...)