Upper and lower plate controls on the great 2011 Tohoku-oki earthquake

Liu, Xin; Zhao, Dapeng

doi:10.1126/sciadv.aat4396

Cited by 54 publications

(61 citation statements)

References 49 publications

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“…These results indicate that the Great Alaska earthquake initiated underneath a high‐V anomaly whereas its large slips occurred beneath a low‐Vs anomaly. It is considered that the upper plate structure (e.g., faults, rock density, and topography) can control the rupture process of large megathrust earthquakes (Bassett et al, ; Bassett & Watts, ; Collot et al, ; X. Liu & Zhao, ; Tassara, ). Taking into account other clues as mentioned above, we think that a difference in rock rigidity of the overriding plate may affect the megathrust rupture.…”

Section: Discussionmentioning

confidence: 99%

“…The spatial distribution from shallow to deep for the megathrust earthquake, long‐term SSEs, and deep tectonic tremors in south‐central Alaska is generally consistent with those in the Nankai (Nishikawa et al, ) and Mexico (Kostoglodov et al, ) subduction zones, reflecting trench‐normal variations of fault behaviors from a seismogenic zone to a transition zone (Audet et al, ; Obara & Kato, ; Peng & Gomberg, ). It is important to investigate the relationship between structural heterogeneity and these different earthquake phenomena (e.g., X. Liu & Zhao, ), but there is still no such a study in south‐central Alaska till today.…”

Section: Introductionmentioning

confidence: 99%

“…It is important to investigate the relationship between structural heterogeneity and these different earthquake phenomena (e.g., X. Liu & Zhao, 2018), but there is still no such a study in south-central Alaska till today.…”

Section: Introductionmentioning

confidence: 99%

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Structural Heterogeneity in Source Zones of the 2018 Anchorage Intraslab Earthquake and the 1964 Alaska Megathrust Earthquake

Gou

Zhao

Huang

et al. 2020

Geochem Geophys Geosyst

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Structural heterogeneities in subduction zones can affect slip behaviors of the megathrust faults and the generation of intraslab earthquakes. In this work we study the 3‐D seismic structures (Vp, Vs, and Poisson's ratio) in and around the source zones of the 2018 Anchorage intraslab earthquake (Mw 7.1) and the 1964 Alaska megathrust earthquake (Mw 9.2). The Anchorage earthquake occurred in an anomalous zone within the subducting Yakutat/Pacific plate with a higher Poisson's ratio than the normal slab. Above the source zone, the overriding North American plate shows a low Vs and a high Poisson's ratio. These features indicate that strong dehydration occurs in the source zone and released fluids ascend into the overlying crust. Two areas with long‐term slow slip events in the Upper and Lower Cook Inlet predominantly exhibit a high Poisson's ratio in the lowermost portion of the crust and the cold nose of the mantle wedge, whereas a low Poisson's ratio zone is revealed between them, suggesting that their segmentation is possibly related to localized slab‐releasing fluids. In the Prince William Sound, the rupture of the 1964 Great Alaska earthquake initiated beneath a high‐V and high Poisson's ratio zone of the overlying crust and the large slips occurred beneath a low‐Vs and high Poisson's ratio zone, suggesting that lateral heterogeneities of the overriding plate may have played an important role in the nucleation and rupture processes of the Great Alaska earthquake.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structural Heterogeneity in Source Zones of the 2018 Anchorage Intraslab Earthquake and the 1964 Alaska Megathrust Earthquake

Gou

Zhao

Huang

et al. 2020

Geochem Geophys Geosyst

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“…Anomalies A and B, beneath southwest Santo, align roughly with the DER (which curves to the south as it subducts; Baillard et al, ), whereas anomalies D and E, near and beneath northwest Malekula, correspond to the continuation of the DFZ's southern volcanic chain. These low‐velocity anomalies may reflect both the high water content of the strongly fractured subducted features through sediments and fluid associated with slab dehydration or change in pore fluid content (Liu & Zhao, ; Mishra et al, ; Ranero et al, ; Zhao et al, ) and a forearc plate damaged zone resulting from the subduction collision of the DFZ. A line through these anomalies crosses the region of maximum Holocene uplift rate on south Santo island (Taylor et al, ), further indicating that these are subducted features that play an important role in the forearc geodynamics.…”

Section: Discussionmentioning

confidence: 99%

The 3‐D Velocity Models and Seismicity Highlight Forearc Deformation Due to Subducting Features (Central Vanuatu)

et al. 2019

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The central Vanuatu forearc is characterized by a reduced convergence rate at the trench, significant uplift of the overriding plate, and the presence of large forearc islands. Volcanic activity and intermediate‐depth seismicity behind the forearc are among the highest on Earth. These features are presumed to be associated with the subduction of a large seamount chain and an immersed ridge. We used a catalog of P and S arrivals from a local seismological network to construct the first 3‐D velocity model of the region and to relocate earthquakes beneath the forearc. The 3‐D model reveals a highly heterogeneous velocity distribution in the first 40 km beneath the surface. Trench‐parallel low P and S velocity zones in the upper tens of kilometers beneath the western edges of the two largest forearc islands correlate to the major features entering into subduction and suggest highly fractured and probably water‐infiltrated features. Trench‐parallel high‐velocity zones at 5–15‐km depth, further to the east, may be part of a continuous consolidated rock structure that acts as a backstop. Thick overriding plate crust (29 ± 3 km) in the forearc is consistent with the presence of continental remnants. The earthquake distribution is generally heterogeneous, suggesting a complex fault structure and variable stress. Earthquakes are, however, well aligned at the plate interface in between the subducting features, where they constrain the angle of subduction to be 15° on average, down to 10–15‐km depth.

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“…Nishikawa et al 22 suggest that different slip behaviors exist in the Tohoku forearc, which may be caused by along-strike variations in pore fluids and lithology of the overriding and subducting plates. Previous tomographic studies [23][24][25] of the Tohoku megathrust zone suggested that the 2011 Tohoku-oki earthquake hypocenter was located in a significant high-velocity (high-V) anomaly, which may represent an asperity in the megathrust zone. These studies have improved our understanding of the structural variation along the plate boundary.…”

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confidence: 99%

Tomography of the source zone of the great 2011 Tohoku earthquake

et al. 2020

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The mechanism and rupture process of the giant 2011 Tohoku-oki earthquake (Mw 9.0) are still poorly understood due to lack of permanent near-field observations. Using seismic arrival times recorded by dense seismograph networks on land and at ocean floor, we determine a detailed seismic tomography model of the megathrust zone beneath the Tohoku forearc. Our results show that the coseismic slip of the 2011 Tohoku-oki earthquake initiated at a boundary between a down-dip high-velocity anomaly and an up-dip low-velocity anomaly. The slow anomaly at shallow depths near the Japan trench may reflect low-rigidity materials that are close to the free surface, resulting in large slip and weak high-frequency radiation. Our new tomographic model can account for not only large slip near the trench but also weak high-frequency radiation from the shallow rupture areas.

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Upper and lower plate controls on the great 2011 Tohoku-oki earthquake

Abstract: The 2011 Tohoku-oki earthquake was caused by structural heterogeneities in both the upper and lower plates.

Cited by 54 publications

References 49 publications

Structural Heterogeneity in Source Zones of the 2018 Anchorage Intraslab Earthquake and the 1964 Alaska Megathrust Earthquake

Structural Heterogeneity in Source Zones of the 2018 Anchorage Intraslab Earthquake and the 1964 Alaska Megathrust Earthquake

The 3‐D Velocity Models and Seismicity Highlight Forearc Deformation Due to Subducting Features (Central Vanuatu)

Tomography of the source zone of the great 2011 Tohoku earthquake

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