Crustal deformation measured by GPS in the South Iceland Seismic Zone due to two large earthquakes in June 2000

Two large earthquakes struck the South Iceland Seismic Zone in June 2000, the first on June 17 (M-w=6.5) and the second on June 21 (M-W=6.4). These are the largest earthquakes in the area in the past 88 years. A network of GPS stations was remeasured following the earthquakes. The whole network was last measured in 1995, and partly in 1999. We correct for the interseismic motion from 1995 to 2000, to obtain the coseismic displacements. The largest coseismic motion we observe is about 0.55 m in the epicentral area of the June 17 event. We model the surface deformation for the two earthquakes using rectangular dislocations in an elastic half space. Best fit uniform slip models indicate that the events occurred on two parallel, N-S vertical faults, with right-lateral strike slip motion. This is the same style of faulting believed to have occurred in large historical earthquake sequences in South Iceland.