environmental sciences research institute - University of Ulster

4.5 GEOPHYSICS RESEARCH
A major focus of geophysics research this year has been our NERC funded project to model the next likely earthquake
and tsunami to affect Sumatra. As details of the next earthquake are unknowable, in practice we model a suite of possible
earthquakes and their consequent tsunamis.
Our starting point is illustrated in Figure 1 where we show the regions that ruptured in the 2004 and 2005 earthquakes,
the stress changes caused by these events, and the approximate rupture areas of previous large earthquakes. The area
of greatest concern for the occurrence of a tsunamigenic earthquake is near Siberut Island as it has experienced a
significant stress increase and hence we assume that the next large earthquake will initiate somewhere in this region
and propagate primarily to the south.
Figure 1: Previous earthquake history on the subduction zone off the coast of Sumatra. Blue patches to the north represent a
portion of the area that slipped in the great 2004 earthquake as well as the rupture zone of the 2005 event. Purple rectangle
immediately south indicates a portion of the trench under the Batu Islands that is believed to be slipping aseismically (i.e. without
experiencing large earthquakes) and hence is unlikely to participate in the next large event. Dotted ovals outline the portions of
the subduction zone that experienced large earthquakes in 1797 and 1833.
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