Abstract
The Solomon megathrust along the western Solomon arc generated two megathrust earthquakes in the past decade (M-w 8.1 in 2007 and M-w 7.1 in 2010). To investigate the interseismic deformation and inferred coupling on the megathrust, we deployed the first continuous GPS network in the Western Solomon Islands. Our 2011-2014 GPS data and the back slip inversion model show coupling ratio as high as 73% along the southeastern 2007 rupture segment but only 10% on average along the segment of 2010 event. Based on the spatial distribution of coseismic slip, aftershock clusters, derived coupling pattern, and paleogeodetic records, we discovered the former as a semipermanent asperity and the latter as a potential megathrust barrier. We propose that a characteristic earthquake of magnitude not less than M-w 8 will recur in an interval of 100 or more years by either single or doublet earthquake.