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Title: Triggering an unexpected earthquake in an uncoupled subduction zone
In the 1970s, the Shumagin Islands region of the Alaska subduction zone was identified as a seismic gap expected to host a future great [moment magnitude ( M w ) ≥8.0] earthquake. More recent geodetic data indicate that this region is weakly coupled, and the geologic record shows little evidence of past large events. From July to October 2020, a series of earthquakes occurred in this region, raising the possibility of greater coupling. The initial M w 7.8 thrust faulting earthquake straddled the eastern edge of the Shumagin Gap and was followed by an M w 7.6 strike-slip earthquake within the Shumagin Gap. Stress modeling indicates that this strike-slip earthquake is in fact favored if the Shumagin Gap has low coupling, whereas a highly coupled Shumagin Gap inhibits that type and location of earthquake. The initial thrust earthquake and its afterslip enhanced the strike-slip loading within the subducting slab, helping to trigger the October event.  more » « less
Award ID(s):
1757581
PAR ID:
10249389
Author(s) / Creator(s):
;
Date Published:
Journal Name:
Science Advances
Volume:
7
Issue:
13
ISSN:
2375-2548
Page Range / eLocation ID:
eabf7590
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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