Seismology: Earthquake stations take long view of Sumatran slip
DOI: 10.1038/nature03675
DOI: 10.1038/nature03696
Two studies published online by Nature on 22 May take a long-distance look at the massive earthquake that caused the devastating Indian Ocean tsunami of 26 December 2004. Data collected by seismic monitoring arrays in Japan and Germany provide the most detailed picture yet of the rupture and how it propagated.
Using data collected by the Hi-Net seismic array in Japan, Miaki Ishii and colleagues report that the rupture propagated in a single direction, taking around eight minutes to travel the 1,300 kilometres from south to north - an average of around 2.8 kilometres per second.
The calculations are based on the first seismic waves to reach the array; the authors add that such a system could in future be used to profile large earthquakes within 20-30 minutes of their occurrence.
A similar, albeit more distant, approach is taken by Frank Krüger and Matthias Ohrnberger, who investigated the rupture using the German Regional Seismic Network, which spans the entire country. At a distance of 9,000 kilometres from the event, they calculate that the rupture initially proceeded at between 2.4 and 2.8 kilometres per second, as it proceeded northwest from its origin, before slowing slightly as it turned due north. The fact that it did not travel far southwards may explain why the subsequent earthquake, on 28 March 2005, occurred mainly to the south of the original.
CONTACT
Miaki Ishii (Scripps Institution of Oceanography, La Jolla, CA, USA)
Tel: +1 858 534 4643; E-mail: [email protected]
Frank Krüger (University of Potsdam, Golm, Germany)
Tel: +49 331 977 5256; E-mail: [email protected]
