Hydroacoustic earthquake detection in the Arctic Basin with the Spinnaker array

Eighteen Arctic Basin earthquakes were hydroacoustically detected during 64 days of monitoring with the Spinnaker hydrophone array in the Lincoln Sea (Arctic Ocean). Epicentral estimates were made for 12 of these events. Even t ranges were estimated via the arrival time difference between the solid e arth P-wave and the hydroacoustic T wave. Azimuths were estimated via plane -wave beamforming to the array elements in the 5-10 Hz band. The 12 events fall on the North American/Eurasian plate boundary at the extreme southern end of the Gakkel Ridge, and along the Spitsbergen Fracture Zone (Lena Trou gh). One of the events (m(b) 5.4, 11 May 1996, Spitsbergen Fracture Zone) w as detected by the Global Seismic Network (GSN) with an epicenter that diff ers from our hydroacoustic estimate by 51 km. Our hydroacoustic detection t hreshold appears to be m(b) similar to3-4 within a similar to 1100 km radiu s of the Spinnaker array, confirming that T waves propagate efficiently in the Arctic Basin and that hydroacoustic techniques hold promise for seismic monitoring of the region.