UNDERWATER EXPLOSIONS AND THE SINKING OF THE KURSK: AN EXPERIMENT IN REGIONAL CALIBRATION
PAQUETTE, A.M., WALLACE, T.C., and KOPER, K., SASO, Dept. of Geosciences, University of Arizona, Tucson, AZ 85721
The exact cause of the sinking of the Russian submarine Kursk on August 12, 2000 remains a subject of controversy. Two events were recorded seismically and located by several research groups in Scandinavia. Analysis of the seismic signals from the second event shows that it is consistent with a 4-7 ton yield explosion detonated at a depth of 80-100 m beneath the surface of the Barents Sea. The Kursk events occurred in a region of the Barents Sea that was essentially aseismic. However, beginning in mid-September a number of additional events were seismically detected in the region of the Kursk wreckage. These events continue to the time of this abstract submission and have been interpreted as depth charges. More than 50 "depth charge" events have occurred in a one-degree square region surrounding the location of the wreckage. Waveforms for these events were obtained from open access AutoDRMs from the U.S. NDC, NORSAR, and IRIS. The data consists of short period and broadband vertical component recordings from stations in the Barents Sea region. Since these events occurred within a small region, they provide an excellent database to evaluate techniques for detecting small events and for seismically calibrating the region. We detect and determine arrival times of the events using a cross-correlation technique that uses both the largest Kursk explosion and several of the larger "depth charge" events as the Green's function. Using Progressive Multiple Event Location, precise relative locations and calibration are determined by simultaneously relocating multiple events and solving for the deviation from the input earth model for each station, commonly referred to as station or path corrections. Clustered events allow for a precise, relative determination of magnitude by assuming the source, path, and station effects are equivalent for all events.