A complex earthquake sequence captured by the continuous GPS network in SW Iceland

Abstract

A complex sequence of earthquakes struck the western part of the South Iceland Scismic Zone (SISZ) on 29 May 2008. The sequence initiated with a M w6.3 (NEIC) earthquake in the western part of the SISZ. Aftershocks from the earthquake delineate two parallel N-S trending structures 4 km apart, in addition to activity along an E-W zone further westward. Continuous GPS measurements can best be explained by right-lateral strike-slip motion on two parallel N-S trending faults, with little slip occurring on other structures illuminated by earthquake activity. We estimate a total moment release of M w6.2, with Mw6.1 on the first rupture and Mw6.0 on the second rupture. High rate ( 1 Hz) CGPS data from a near-field station suggest that the main asperity on the Kross fault ruptured within 3 s of the initial mainshock on the Ingólfsfjall fault. Copyright 2009 by the American Geophysical Union.