Monday, April 22, 2013

Review Article: Recurrence Of Great Subduction Zone Earthquakes

Open Access in Current Science

Kusala Rajendran

The last decade has witnessed two unusually large tsunamigenic earthquakes. The devastation from the 2004 Sumatra–Andaman and the 2011 Tohoku-Oki earthquakes (both of moment magnitude ≥ 9.0) and their ensuing tsunamis comes as a harsh reminder on the need to assess and mitigate coastal hazards due to earthquakes and tsunamis worldwide. Along any given subduction zone, megathrust tsunamigenic earthquakes occur over intervals considerably longer than their documented histories and thus, 2004-type events may appear totally ‘out of the blue’. In order to understand and assess the risk from tsunamis, we need to know their long-term frequency and magnitude, going beyond documented history, to recent geological records. The ability to do this depends on our knowledge of the processes that govern subduction zones, their responses to interseismic and coseismic deformation, and on our expertise to identify and relate tsunami deposits to earthquake sources. In this article, we review the current state of understanding on the recurrence of great thrust earthquakes along global subduction zones.

The figure above shows the  Cascadia subduction zone, Pacific coast of N. America (source Rajendran 2013) . I looked through the Reference section and saw a number of recent papers addressing both the evidence for past earthquakes as well as the impact of the 2004 Sumatra earthquake on the Indian coastline. The acknowledgements indicate funding for this paper from the Ministry of Earth Sciences, Govt. of India. Its good to see basic geological research into subduction zone earthquakes being supported this way.

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