Slip distribution from the 1 April 2007 Solomon Islands earthquake: A unique image of near‐trench rupture

Abstract

We estimate the slip distribution from the MW 8.1 Solomon Islands earthquake in 2007, from two post‐seismic surveys measuring uplifted coral and submerged coastal features. The occurrence of islands extremely proximal to the trench and nucleation of rupture allowed for the collection of unprecedented coseismic deformation dataset along a large megathrust earthquake. Using data from the two surveys along the southeastern half of the slip zone within five weeks of the event, we model the elastic dislocation to identify the optimal (29°), and alternate (20°), dip and distribution of thrust along the southern rupture. The vertical deformation, which includes both coseismic and early postseismic deformation, has highly variable and large slip within 25 km of the trench and straddling Ranongga Island. The shallow focus of slip in the near‐trench area may explain the locally high tsunami run‐up on portions of Simbo Island, however the aseismic contribution of afterslip remains unknown.