A Flying Start, Then a Slow Slip.

The human tragedy caused by the Sumatra-Andaman earthquake (momentmagnitude 9.3) on 26 December 2004 and its companion Nias earthquake(moment magnitude 8.7) on 28 March 2005 is difficult to comprehend.These earthquakes, the largest in 40 years, have also left seismologistssearching for the words and tools to describe the enormity of thegeological processes involved. Four papers in this issue discuss aspectsof a rupture process of surprising complexity, the first such event totest the sensitivity and range of many new technologies. A surprisingfeature of the earthquake is that after the initial rapid rupture,subsequent slip of the plate interface occurred with decreasing speedtoward the north. [ABSTRACT FROM AUTHOR]