Yesterday's quakes killed about ten people, some from falling masonry. The tsunami generated was about three metres high, not enough to cause serious damage, even though the revised magnitude of the temblor
was 8.4, the biggest since the one that hit Aceh and caused the
have been reported today in the Mentawai Islands region:
150 km (95 miles) SSW of Padang, Sumatra
330 km (205 miles) WNW of Bengkulu, Sumatra
625 km (385 miles) SSW of Kuala Lumpur, Malaysia
885 km (550 miles) WNW of Jakarta, Java.
No tsunamis have been reported.
Seismotectonics of the Indonesian RegionThe Indonesian region is one of the most seismically active zones of the earth; at the same time it has a leading position from the point of view of active and potentially active volcanoes. It is a typical island-arc structure with its characteristic physiographic features, such as a deep oceanic trench, a geanticline belt, a volcanic inner arc and a marginal basin.
In most subduction zones, motion of the subducted plate is nearly perpendicular to the trench axis. In some cases, for example Sumatra, where the motion is oblique to the axis, a strike-slip fault zone is seen, and is lying parallel to the volcanic chain.
In plain language, this means that the Mentawai group of islands are in danger of being tipped into the Java Trench, which I believe would be a great shame. I've visited and written about the peoples of these islands a few times, such as here
Incidentally, there doesn't seem to be such a thing as an 'earthquake season'. They happen year round here ~ but there was another one today
at the eastern end of the 'Ring of Fire'.