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2018 M_W 7.9 Gulf of Alaska Earthquake: Multiple Fault Rupture in the Pacific Plate

Lay, Thorne and Ye, Lingling and Bai, Yefei and Cheung, Kwok Fai and Kanamori, Hiroo (2018) 2018 M_W 7.9 Gulf of Alaska Earthquake: Multiple Fault Rupture in the Pacific Plate. Geophysical Research Letters, 45 (18). pp. 9542-9551. ISSN 0094-8276. doi:10.1029/2018gl079813.

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A major (M_W 7.9) intraplate earthquake ruptured the Pacific plate seaward of the Alaska subduction zone near Kodiak Island on 23 January 2018. The aftershock seismicity is diffuse, with both NNW‐ and ENE‐trending distributions, while long‐period point source moment tensors have near‐horizontal compressional and tensional principal strain axes and significant non‐double‐couple components. Backprojections from three large‐aperture networks indicate sources of short‐period radiation not aligned with the best double‐couple fault planes. A suite of finite‐fault rupture models with one to four faults was considered, and a four‐fault model, dominated by right‐lateral slip on an SSE trending, westward‐dipping fault, is compatible with most seismic, GPS, and tsunami data. However, the precise geometry, timing, and slip distribution of the complex set of faults is not well resolved. The sequence appears to be the result of intraplate stresses influenced by slab pull, the 1964 Alaska earthquake, and collision of the Yakutat terrane in northeastern Alaska.

Item Type:Article
Related URLs:
URLURL TypeDescription
Lay, Thorne0000-0003-2360-4213
Ye, Lingling0000-0002-8739-2072
Bai, Yefei0000-0003-3323-3348
Cheung, Kwok Fai0000-0002-7435-0500
Kanamori, Hiroo0000-0001-8219-9428
Additional Information:© 2018 American Geophysical Union. Received 31 JUL 2018; Accepted 4 SEP 2018; Accepted article online 10 SEP 2018; Published online 22 SEP 2018. The Incorporated Research Institutions for Seismology (IRIS) data management service (DMS) ( was used to access the seismic data from Global Seismic Network and Federation of Digital Seismic Network stations. Broadband data from China were obtained from the Data Management Centre of China National Seismic Network at Institute of Geophysics, Chinese Earthquake Administration (doi: 10.11998/SeisDmc/SN, GPS rapid solutions estimated by Tom Herring were accessed from the UNAVCO webpage ( Tsunami waveform data were obtained from the NOAA National Data Buoy Center ( and Ocean Networks Canada ( K. D. Koper kindly provided his backprojection software and training in its use. We thank editor Gavin Hayes, Jeff Freymueller, and an anonymous reviewer for helpful comments. This work was supported by NSF grant EAR1802364 to Thorne Lay and the junior Thousand Talents Plan of China and the 100 Talents program of Sun Yat‐sen University to Lingling Ye.
Group:Seismological Laboratory
Funding AgencyGrant Number
Sun Yat-sen UniversityUNSPECIFIED
China 1000-Young Talents PlanUNSPECIFIED
Subject Keywords:Gulf of Alaska; 2018 earthquake; plate deformation; outer‐rise rupture; intraplate earthquake; complex faulting
Issue or Number:18
Record Number:CaltechAUTHORS:20181212-123932303
Persistent URL:
Official Citation:Lay, T., Ye, L., Bai, Y., Cheung, K. F., & Kanamori, H. (2018). The 2018 MW 7.9 Gulf of Alaska earthquake: Multiple fault rupture in the Pacific plate. Geophysical Research Letters, 45, 9542–9551.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:91731
Deposited By: Tony Diaz
Deposited On:12 Dec 2018 20:53
Last Modified:16 Nov 2021 03:43

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