Hydroacoustic Earthquake Detection in the Arctic Basin with the Spinnaker Array

Abstract

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. Event ranges were estimated via the arrival time difference between the solid earth 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 Trough). One of the events ( m b 5.4, 11 May 1996, Spitsbergen Fracture Zone) was detected by the Global Seismic Network (GSN) with an epicenter that differs from our hydroacoustic estimate by 51 km. Our hydroacoustic detection threshold appears to be m b ∼3–4 within a ∼1100 km radius 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.