Co-seismic 3d gravity model for 2010 Chile earthquake

Co-seismic 3-D density distribution within crust and mantle along with other physical properties in seismogenic region of offshore mega-thrust earthquakes like Chile Earthquake 2010 can help understanding Earth's instantaneous site geodynamic response. We modeled carefully isolated co-seismic GRACE gravity response by a novel unit vertical pyramid based six-layered 3-D forward gravity mega-thrust fault model for Chile earthquake 2010, which honours co-seismic deformation of sea surface to hypocenter region (hypocenter depth of 35 km, rupture length of 700 km and dip slip of 15.38 m). Our gravity model provides a snapshot of episodic subduction of Nazca plate below South American Plate. The computed gravity response closely matches the observed gravity (RMS error of 5.776×10−12µgal) while fully accounting for co-seismic mass redistribution. Further, our gravity analysis has independently inferred rupture length, instantaneous velocity, average seismic moment magnitude and momentum as 700km, 2.89km/s, 1.48×1022Nm and 7.72×1016 GNs respectively, which fairly agree with the literature. Our model inferred momentum at sea floor corresponds to an area pulse that led to Tsunami generation.