5 September 2002

Seismology: Stresses and strains beneath an island volcano

Bathymetry from GSI, seismicity from ERI; imagery by Serkan Bozkurt and Shinji Toda.

The most energetic seismic swarm known struck 60 km south of Japan's Izu peninsula in 2000. Over 7,000 earthquakes (disks proportional to magnitude) were accompanied by steam and debris eruptions of Miyake volcano (centre right on cover). The swarm was triggered by magma-related changes in stress. Stressing rate changes (warm colours denote increases; cool, decreases) are shown draped over the bathymetry, with coastlines brown.

Evidence from the AD 2000 Izu islands earthquake swarm that stressing rate governs seismicity
SHINJI TODA, ROSS S. STEIN & TAKESHI SAGIYA
Nature 419, 58–61 (2002); doi:10.1038/nature00997
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Seismology: Stressed to quaking point
CHRIS MARONE
The Earth's crust can deform catastrophically in earthquakes, but it's difficult to predict exactly what causes such failure. Analysing thousands of small shocks might help us better understand how earthquakes occur.
Nature 419, 32 (2002); doi:10.1038/419032a
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