SGER: Resolving Coseismic Stress Drop, Afterslip, and Viscous Relaxation Caused by Mw=8.3, November 15, 2006 Kuril Earthquake: Evidence from GPS

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The Kuril subduction zone at the northwest Pacific Ocean margin is the plateboundary where the Pacific plate is rapidly underthrusting the North American plate. Great Mw=8.3November 15, 2006 Kuril earthquake ruptured one of the most conspicuous gaps in the subduction-zoneseismic activity; it occurred on the 600-km long Kuril arc segment with not a single great earthquake forabout a century. In the same time interval, the segments to the north (Kamchatka) and south (the southernKurils and Hokkaido) exhibited several great earthquakes. This Small Grant for ExploratoryResearch addresses a unique opportunity to resolve and analyze coseismic stress drop, afterslip, andviscous relaxation following this recent earthquake. This SGER proposal focuses on making in May 2007the critical time-sensitive observations that will enable the studies of this earthquake and itsconsequences. The proposed project addresses several important questions that arise in connection withthis event. How much of the strain built up from the subduction of the Pacific plate beneath the NorthAmerican plate (or the Okhotsk plate) has been released on November 15, 2006 coseismically andpostseismically? What is the danger of further great earthquakes accompanied by Pacific-wide tsunamisin the central and northern Kurils?The research relies on a combination of continuous GPS (CGPS) stations over the Kuril arc established several months before the November 15, 2006 earthquake and new CGPS stations that the investigators intend to install on the islands nearest to the rupture of the earthquake. To accomplish the goal of the project, the investigators will use a cruise of the ship of NOAA, which shall start in mid-May 2007 from Petropavlovsk, Kamchatka to many Kuril islands.Broader Impacts include international collaborations with Russian scientists, research that may impact earthquake hazards and important data collection.