Coseismic stress changes and crustal deformation on the Reykjanes Peninsula due to triggered earthquakes on 17 June 2000

A large (Mw = 6.5) earthquake struck the South Iceland Seismic Zone (SISZ) on 17 June 2000. The 17 June main shock triggered increased seismicity over a large area and significant slip on at least three distinct faults on the Reykjanes Peninsula, up to 87 km to the west of the event. A second large (Mw = 6.4) earthquake in the SISZ occurred on 21 June 2000, about 17 km west of the 17 June main shock. This event does not appear to have triggered as much activity on the Reykjanes Peninsula as the 17 June main shock, although the epicenter was closer. Crustal deformation signals due to the June 2000 earthquakes on the Reykjanes Peninsula were observed with campaign and continuous GPS and synthetic aperture radar interferometry, with the largest coseismic deformation signal near lake Kleifarvatn. We model the faults using three uniform slip rectangular dislocations in an elastic half‐space. Best fit uniform slip models consistent with seismic and geodetic data indicate that all three faults trend N‐S and the motion on them was primarily right‐lateral strike slip. Our study suggests that the event near Kleifarvatn had a significantly larger moment than seismic estimates, indicating a component of aseismic slip on the fault lasting no more than several hours. Static Coulomb failure stress change calculations indicate that the event at Kleifarvatn increased the Coulomb stress at the hypocenter of the Núpshlídarháls event by 0.1–0.2 MPa as well as loading the Hvalhnúkur fault.