TY - JOUR
T1 - Upper Plate Structure and Megathrust Properties in the Shumagin Gap Near the July 2020 M7.8 Simeonof Event
AU - Shillington, Donna J.
AU - Bécel, Anne
AU - Nedimović, Mladen R.
N1 - Funding Information:
We thank the captain, crew, and scientific staff of the R/V and personnel from the Ocean Bottom Seismic Instrument Pool at Scripps Oceanographic Institution, who made the acquisition of ALEUT data possible. Funding was provided by NSF grants OCE‐0926614 and EAR‐1347312. We thank Christine Regalla and James Gaherty for discussions, and Jean‐Xavier Dessa and two anonymous reviewers for constructive comments that improved the manuscript. Marcus G. Langseth
Funding Information:
We thank the captain, crew, and scientific staff of the R/V Marcus G. Langseth and personnel from the Ocean Bottom Seismic Instrument Pool at Scripps Oceanographic Institution, who made the acquisition of ALEUT data possible. Funding was provided by NSF grants OCE-0926614 and EAR-1347312. We thank Christine Regalla and James Gaherty for discussions, and Jean-Xavier Dessa and two anonymous reviewers for constructive comments that improved the manuscript.
Publisher Copyright:
© 2022. American Geophysical Union. All Rights Reserved.
PY - 2022/1/28
Y1 - 2022/1/28
N2 - Subduction zone architecture and properties are thought to control megathrust slip behavior, but few constraints on crustal structure and megathrust properties are available at sufficient resolution and depth, hindering understanding of linkages between structure and behavior. Here we present a P-wave seismic velocity model based on wide-angle seismic data integrated with collocated reflection imaging in the weakly coupled Shumagin Gap in the Alaska subduction zone, where a M7.8 occurred in July 2020. We show that this earthquake occurred near and below the Moho of the overriding plate where the megathrust is characterized by a 3- to 5-km-thick reflection band interpreted to represent tectonic mixing. The rheological heterogeneity of the plate boundary near and below the Moho could account for abundant interplate seismicity, repeated M7.x events, and patchiness of the 2020 rupture. Velocity variations in the overriding continental crust imply changes in rigidity that could further influence megathrust slip.
AB - Subduction zone architecture and properties are thought to control megathrust slip behavior, but few constraints on crustal structure and megathrust properties are available at sufficient resolution and depth, hindering understanding of linkages between structure and behavior. Here we present a P-wave seismic velocity model based on wide-angle seismic data integrated with collocated reflection imaging in the weakly coupled Shumagin Gap in the Alaska subduction zone, where a M7.8 occurred in July 2020. We show that this earthquake occurred near and below the Moho of the overriding plate where the megathrust is characterized by a 3- to 5-km-thick reflection band interpreted to represent tectonic mixing. The rheological heterogeneity of the plate boundary near and below the Moho could account for abundant interplate seismicity, repeated M7.x events, and patchiness of the 2020 rupture. Velocity variations in the overriding continental crust imply changes in rigidity that could further influence megathrust slip.
KW - Alaska subduction zone
KW - marine seismic data
KW - megathrust
KW - Shumagin Gap
UR - http://www.scopus.com/inward/record.url?scp=85123772538&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85123772538&partnerID=8YFLogxK
U2 - 10.1029/2021GL096974
DO - 10.1029/2021GL096974
M3 - Letter
AN - SCOPUS:85123772538
VL - 49
JO - Geophysical Research Letters
JF - Geophysical Research Letters
SN - 0094-8276
IS - 2
M1 - e2021GL096974
ER -