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The two largest earthquakes of the past 40 years ruptured a 1600-kilometer-long portion of the fault boundary between the Indo-Australian and southeastern Eurasian plates on 26 December 2004 [seismic moment magnitude ([M.sub.w]) = 9.1 to 9.3] and 28 March 2005 ([M.sub.w] = 8.6). The first event generated a tsunami that caused more than 283,000 deaths. Fault slip of up to 15 meters occurred near Banda Aceh, Sumatra, but to the north, along the Nicobar and Andaman Islands, rapid slip was much smaller. Tsunami and geodetic observations indicate that additional slow slip occurred in the north over a time scale of 50 minutes or longer., The 26 December 2004 Sumatra-Andaman earthquake was the largest seismic event on Earth in more than 40 years, and it produced the most devastating tsunami in recorded history (1). Like [...]

Most earthquakes follow a simple scaling relationship such that the duration of fault movement is proportional to [10.sup.M/2], where M is the earthquake moment magnitude. The typical duration of an [...], We have detected dozens of previously unknown, moderate earthquakes beneath large glaciers. The seismic radiation from these earthquakes is depleted at high frequencies, explaining their nondetection by traditional methods. Inverse modeling of the long-period seismic waveforms from the best-recorded earthquake, in southern Alaska, shows that the seismic source is well represented by stick-slip, downhill sliding of a glacial ice mass. The duration of sliding in the Alaska earthquake is 30 to 60 seconds, about 15 to 30 times longer than for a regular tectonic earthquake of similar magnitude.