The central region of the Bering Sea is virtually aseismic. In the north, a wide diffuse zone of seismicity extends from western Alaska across the Bering Strait into eastern Russia. This zone is believed to mark the northern boundary of the Bering microplate. The southern edge of the Bering Sea is marked by the Aleutian Arc, where seismicity is associated with the ongoing subduction processes.
In 1991, a magnitude 6.6 earthquake occurred about 210 km (150 miles) to the southeast of the April 30, 2010 earthquakes. The 1991 and 2010 earthquakes indicate N-S extension and E-W compression of the crust.
The source area of the April 30, 2010 event might be structurally linked to the graben-like structure that underlies the headwall area of Zhemchug Canyon, which is the largest submarine canyon in the world (by volume). Both the mainshock and largest aftershock are strike-slip earthquakes. The structural grain of the headwall structures is NW-SE, parallel to the left-lateral nodal plane of the April 30 events. The right-lateral nodal plane is parallel to the crustal fabric of the hypothetical offshore continuation of the great family of NE-SW trending strike-slip faults of western Alaska (Kaltag, Kobuk, Denali, etc.). If these crustal structures continue offshore, they may be the source of the April 30 earthquakes.
Last Modified: May 13, 2020