The deep Shumagin gap filled: Kinematic rupture model and slip budget analysis of the 2020 Mw 7.8 Simeonof earthquake constrained by GNSS, global seismic waveforms, and floating InSAR

Xiao, Zhuohui; Freymueller, J. T.; Grapenthin, Ronni; Elliott, Julie; Drooff, Connor; Fusso, L.

doi:10.1016/j.epsl.2021.117241

Cited by 42 publications

(83 citation statements)

References 36 publications

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“…Using teleseismic and high-rate Global Navigation Satellite System (GNSS) waveforms, static GNSS offsets, and interferometric synthetic aperture radar (InSAR) line-of-sight (LOS) offsets for separate patches of coherent pixels (Fig. 2) that are either tied to static GNSS offsets or “floating” with an ambiguity parameter estimated during the inversion ( 6 ), we infer the coseismic slip model in Fig. 3 (details in Materials and Methods).…”

Section: Resultsmentioning

confidence: 99%

“…Red dot marks the hypocenter of Chignik event, and arrow points to the focal mechanism for that earthquake. Grid shows the model fault plane for Simeonof event ( 6 ). Two coefficients of friction (0.1 and 0.4) are shown.…”

Section: Resultsmentioning

confidence: 99%

“…1) or 2.5 m of slip (based on westernmost coseismic estimate, which is in lower-coupled region) had accumulated by 2020, meeting or exceeding the estimated slip during the 1938 earthquake. A major caveat to this potential increased seismic hazard is that the 1938 earthquake occurred at shallower depths where we do not have direct geodetic constraints and coupling estimates are strongly influenced by model regularization ( 6 ). Another reason to question the seismic hazard around the region of the 1938 earthquake is the extremely rapid afterslip observed at AC13 on Chirikof Island (fig.…”

Section: Discussionmentioning

confidence: 99%

“…The method to estimate time evolving slip on a fine fault from seismic and geodetic data is described by Xiao et al . ( 6 ) who expand a nonlinear wavelet-based inversion routine ( 48 ) to estimate parameters that capture missing phase cycles of the floating InSAR patches.…”

Section: Methodsmentioning

confidence: 99%

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Cascading rupture of a megathrust

et al. 2022

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Understanding variability in the size and location of large earthquakes along subduction margins is crucial for evaluating seismic and tsunami hazards. We present a coseismic slip model for the 2021 M 8.2 Chignik earthquake and investigate the relationship of this earthquake to previous major events in the Alaska Peninsula region and to interseismic coupling. Stress changes from the 2020 M 7.8 Simeonof event triggered the Chignik event, and together, the earthquakes partially filled an unruptured section along a 3000-km subduction margin that has experienced a series of ruptures along almost its entire length over the past century. Variations in coupling and structural characteristics may make the region more prone to nucleating M 7 to M 8 events rather than larger M > 8.5 earthquakes. Stress changes and rupture areas suggest that the two recent earthquakes may be part of an 80-year-long rupture cascade and may have advanced seismic hazard in the region.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Cascading rupture of a megathrust

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“…assumption (Xiao et al, 2021). It is well known that land-based geodetic slip deficit estimates have limited near-trench resolution.…”

Section: Discussionmentioning

confidence: 99%

The 29 July 2021 M_W 8.2 Chignik, Alaska Peninsula Earthquake Rupture Inferred From Seismic and Geodetic Observations: Re‐Rupture of the Western 2/3 of the 1938 Rupture Zone

Liu

Lay

Xiong

2022

Geophysical Research Letters

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The Pacific plate underthrusts the North America plate along the Alaska-Aleutian subduction zone, producing great earthquake ruptures along most of the arc (e.g., Sykes et al., 1981). Southwest of the great 1964 Alaska rupture zone, the Semidi segment offshore of the Alaska Peninsula (Figure 1) has experienced several great earthquakes. On 29 July 2021, an M W 8.2 thrust-faulting earthquake ruptured this region. This is the largest earthquake to strike U.S. territory in 55 years. The 2021 aftershock distribution overlaps the rupture zone of an M W 8.2 event in 1938, which had an aftershock zone and tsunami source region extending approximately 270-300 km along the megathrust (e.g.,

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An Alaska–Aleutian Subduction Zone Interface Earthquake Recurrence Model From Geology and Geodesy

Briggs,

Witter,

Freymueller

et al. 2024

Geophysical Monograph Series

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The deep Shumagin gap filled: Kinematic rupture model and slip budget analysis of the 2020 Mw 7.8 Simeonof earthquake constrained by GNSS, global seismic waveforms, and floating InSAR

Cited by 42 publications

References 36 publications

Cascading rupture of a megathrust

Cascading rupture of a megathrust

The 29 July 2021 M_W 8.2 Chignik, Alaska Peninsula Earthquake Rupture Inferred From Seismic and Geodetic Observations: Re‐Rupture of the Western 2/3 of the 1938 Rupture Zone

An Alaska–Aleutian Subduction Zone Interface Earthquake Recurrence Model From Geology and Geodesy

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The deep Shumagin gap filled: Kinematic rupture model and slip budget analysis of the 2020 Mw 7.8 Simeonof earthquake constrained by GNSS, global seismic waveforms, and floating InSAR

Cited by 42 publications

References 36 publications

Cascading rupture of a megathrust

Cascading rupture of a megathrust

The 29 July 2021 MW 8.2 Chignik, Alaska Peninsula Earthquake Rupture Inferred From Seismic and Geodetic Observations: Re‐Rupture of the Western 2/3 of the 1938 Rupture Zone

An Alaska–Aleutian Subduction Zone Interface Earthquake Recurrence Model From Geology and Geodesy

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Product

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The 29 July 2021 M_W 8.2 Chignik, Alaska Peninsula Earthquake Rupture Inferred From Seismic and Geodetic Observations: Re‐Rupture of the Western 2/3 of the 1938 Rupture Zone