Abstract:
To investigate the transient strain rate of postseismic deformation associated with the highly
devastating December 26, 2004 Andaman–Sumatra earthquake (Mw 9.3), a combined
analysis have been done using GPS data and Seismic Moment Tensors (SMT) acquired
from Andaman–Nicobar–Sumatra regions during 2005–2007. The displacement estimated
during postseismic periods 2005–2006 and 2006–2007with respect to ITRF2008 and Indian
Reference Frame, display dominating arc-normal active deformation in the southern part
close to epicenter, and arc-parallel deformation towards the northern part of the Andaman–
Nicobar–Sumatra Subduction Zone (ANSSZ). The principal strain rates during 2005–2006
periods indicate larger strain accumulation and decreased rate of strain during 2006–2007
with a maximum arc-normal compression on southern part of ANSSZ and a changing trend
of arc-parallel extension towards the central and northern part along the ANSSZ. Stress
inversion using SMT also indicate compressive horizontal stress in the southern part and
extensional stress towards the central and northern part of the study area, and a remarkable
agreement with GPS derived strain rate pattern.
