Editor's Summary
5 November 2009
Aftershock or small quake?
The assessment of earthquake hazards within continents relies in large part on the assumption that the locations of small earthquakes in the historical record reflect continuing deformation that will cause future large earthquakes. However, this assumption is beginning to look suspect. As demonstrated by the Wenchuan earthquake of May 2008, faults with low recent seismicity are not immune from large earthquakes. And now Seth Stein and Mian Liu argue that many recent intraplate earthquakes are probably aftershocks of large earthquakes that occurred hundreds of years ago, so do not point to the location of future large earthquakes. Stein and Liu present a simple model predicting that the duration of aftershock sequences varies inversely with the rate at which faults are loaded. Thus the common practice of treating continental earthquakes as steady-state seismicity may overestimate the hazard in currently active areas and underestimate it elsewhere.
News and Views: Earth science: Lasting earthquake legacy
Earthquakes occur within continental tectonic plates as well as at plate boundaries. Do clusters of such mid-plate events constitute zones of continuing hazard, or are they aftershocks of long-past earthquakes?
Tom Parsons
doi:10.1038/462042a
Letter: Long aftershock sequences within continents and implications for earthquake hazard assessment
Seth Stein & Mian Liu
doi:10.1038/nature08502
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