Rupture Along 400 km of the Bering Fracture Zone in the Komandorsky Islands Earthquake (MW 7.8) of 17 July 2017. Issue 24 (23rd December 2017)

• Record Type: Journal Article
• Authors: Lay, Thorne; Ye, Lingling; Bai, Yefei; Cheung, Kwok Fai; Kanamori, Hiroo; Freymueller, Jeffrey; Steblov, Grigory M.; Kogan, Mikhail G.
• Is Part Of: Geophysical research letters. Volume 44:Issue 24(2017)
• Page Start: 12, 161
• Page End: 12, 169
• Publication Date: 2017-12-23
• Subjects: Komandorsky Islands -- 2017 earthquake -- Bering Fracture Zone -- slip partitioning -- western Aleutians -- strike‐slip faulting; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2017GL076148
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: The 17 July 2017 Komandorsky Islands M W 7.8 earthquake involved arc‐parallel right‐lateral patchy strike‐slip faulting along ~400 km of the Bering Fracture Zone (BFZ) in the westernmost Aleutian Islands back arc. The large size of the earthquake indicates that the BFZ serves regionally as the primary plate boundary extending from the Near Islands to Kamchatka, with the fore‐arc Komandorsky Sliver translating rapidly parallel to the Aleutian Trench. The slip distribution is determined by analysis of seismic, tsunami, and geodetic observations. Fault displacements of 4 to 8.5 m, mostly in the upper 15 km, but with localized extension to 20 to 30 km depth along a ~100 km long segment of the BFZ, are comparable to the possible slip deficit since the last major earthquakes in this region in 1849 and 1858, given an estimated 5.1 cm/yr rate between the Komandorsky Sliver and the Bering Plate. Plain Language Summary: A large earthquake struck the westernmost portion of the Aleutian Island arc on 17 July 2017. In this region the Pacific plate is moving relative to the North American plate parallel to the plate boundary, with no convergence. As a result the plate motion is accommodated on a strike‐slip fault in the upper plate, located along the Bering Fracture Zone. The earthquake produced slip and aftershocks along a 400 km long stretch of the Bering Fracture Zone in a magnitude 7.8 earthquake. The slip distribution and time history are determined by modeling seismic, geodetic, and tsunami data. The event is comparable in length and seismic moment to the 1906 San Francisco earthquake on the San Andreas Fault. Key Points: The 17 July 2017 Komandorsky Islands earthquake ruptured the back‐arc Bering Fracture Zone between the Komandorsky Sliver and Bering Plate Right‐lateral strike‐slip faulting with patchy slip extended ~400 km along strike including a southeastern large‐slip patch ~100 km long The slip was sufficient to release strain accumulated since the last rupture in 1858; the BFZ is the primary plate boundary in the region