This is an abstract of a talk presented at American Geophysical Union, Fall Meeting 2011. Active deformation along the western margin of the present day Mentawai forearc basin appeared as anticlinal ridges. Beneath the anticlinal ridges, the deformation zone exhibits (1) main backthrust, as the upward continuation of the Mentawai Backthrust in forearc basin, (2) seaward verging imbricated thrusts developed in the accretionary wedge and (3) the landward verging thrust developed in the forearc basin. The landward verging Mentawai Backthrust zone and together with the Frontal Thrusts, formed the doubly vergent active tectonics in the Sumatra subduction system.
Tektonesiana 