Figure 1

Earthquake-prone area in west coast of Sumatra island. Modified from Vigny [2]. Red dots show large subduction earthquake epicentre, yellow dots depict the aftershocks occurring within one month after the main shock. The red star shows the epicentre of September 30th, Padang earthquake. The inset box, shows the amount of average slip (in meters) associated to each earthquake since 2000 and the obvious slip deficit in front of Padang, which will have to catch up with the remaining of the subduction sooner or later, in successive medium-size events or in one larger.