THE Sumatra stretch of the Indo-Australia tectonic plate, which caused the magnitude 9 earthquake near Aceh last year, could be unusually susceptible to major earthquakes, according to research completed before the earthquake struck.
As the Indo-Australia plate slides under the Burma plate, most of the energy is absorbed deep within the Earth, but a small proportion is reflected back to the shallow levels of the plate where damaging quakes occur. Mike Sandiford of the University of Melbourne in Australia and his colleagues modelled the energy distribution in two sections of the plate near Sumatra and Java.
鈥淭he tectonic plate near Aceh could be unusually susceptible to major quakes鈥�
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They found that up to 10 per cent of the energy is transmitted back towards the surface, and that the Sumatra slab receives almost twice as much energy as the Java slab, probably because it does not go as deep (Geology, vol 33, p 113). This could explain why so many earthquakes strike here 鈥� quakes that are slowly splitting the Indo-Australia plate into two.
