Coseismic slip distribution of the February 27, 2010 Mw 8.8 Maule, Chile earthquake

Abstract

Static offsets produced by the February 27, 2010 M-w = 8.8 Maule, Chile earthquake as measured by GPS and InSAR constrain coseismic slip along a section of the Andean megathrust of dimensions 650 km (in length) x 180 km (in width). GPS data have been collected from both campaign and continuous sites sampling both the near-field and far field. ALOS/PALSAR data from several ascending and descending tracks constrain the near-field crustal deformation. Inversions of the geodetic data for distributed slip on the megathrust reveal a pronounced slip maximum of order 15 m at similar to 15-25 km depth on the megathrust offshore Lloca, indicating that seismic slip was greatest north of the epicenter of the bilaterally propagating rupture. A secondary slip maximum appears at depth similar to 25 km on the megathrust just west of Concepcicn. Coseismic slip is negligible below 35 km depth. Estimates of the seismic moment based on different datasets and modeling approaches vary from 1.8 to 2.6 x 10 N m. Our study is the first to model the static displacement field using a layered spherical Earth model, allowing us to incorporate both near-field and far-field static displacements in a consistent manner. The obtained seismic moment of 1.97 x 10 N m, corresponding to a moment magnitude of 8.8, is similar to that obtained by previous seismic and geodetic inversions.