Geometry and spatial variations of seismic reflection intensity of the upper surface of the Philippine Sea plate off the Boso Peninsula, Japan

Kono, Akihiro; Sato, Toshinori; Shinohara, Masanao; Mochizuki, Kimihiro; Yamada, Tomoaki; Uehira, Kenji; Shinbo, Toshio; Machida, Yuya; Hino, Ryota; Azuma, R.

doi:10.1016/j.tecto.2017.05.001

Cited by 7 publications

(11 citation statements)

References 41 publications

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“…In the landward area, the upper boundaries estimated by the present study coincide with those of Uchida et al (2010) at a depth of 30 km. The upper boundary of the PHS delineated by the present study is consistent with that compiled by Kono et al (2017) at 15 km depth (Fig. 5b).…”

Section: Upper Boundary Of the Phssupporting

confidence: 88%

“…5b). The boundary is shallower than that by Kono et al (2017) at the greater depths, perhaps because the Kono et al 's iso-depth at 20 km depth was delineated by a land-based study (Hirose et al 2008).…”

Section: Upper Boundary Of the Phsmentioning

confidence: 93%

“…The other symbols are same as those defined in Fig. 3 Uchida et al (2010) and compiled by Kono et al (2017). The location of the low-velocity anomaly in the NA plate is indicated by the black circle labeled "B. "…”

Section: Upper Boundary Of the Phsmentioning

confidence: 99%

“…Several offshore refraction studies have been performed to determine the crustal structure (Nakahigashi et al 2012;Kono et al 2017); however, these studies have allowed only two-dimensional model along the survey lines to be constructed.…”

Section: Introductionmentioning

confidence: 99%

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Tomographic image of crust and upper mantle off the Boso Peninsula using data from an ocean-bottom seismograph array

Ito

Yamamoto

Hino

et al. 2017

Earth Planets Space

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We determined the three-dimensional structure of the crust and upper mantle off the Boso Peninsula, Japan, by analyzing seismograms recorded by ocean-bottom seismometers and land stations between 2011 and 2013. We employed seismic tomography to determine the P-and S-wave velocity structures and earthquake locations simultaneously. The tomographic image shows that the mantle parts of the Pacific and the Philippine Sea plates have highvelocity anomalies. The upper boundary of the Philippine Sea plate is delineated as approximately 2-6 km shallower than that previously estimated from land-based data for the area 140.5°E-141.5°E and 35°N-35.5°N. A pronounced low-velocity anomaly in P-and S-waves with low-V p /V s ratio (1.5-1.6) was observed at depths shallower than 20 km in the overriding North American plate. This anomaly may be caused by the presence of rocks with a low-V p /V s ratio, such as quartzite, and the water expelled from the subducted Pacific and Philippine Sea plates.

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Section: Upper Boundary Of the Phssupporting

confidence: 88%

Section: Upper Boundary Of the Phsmentioning

confidence: 93%

Section: Upper Boundary Of the Phsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Tomographic image of crust and upper mantle off the Boso Peninsula using data from an ocean-bottom seismograph array

Ito

Yamamoto

Hino

et al. 2017

Earth Planets Space

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“…9. The black circles indicate the low-angle thrust-faulting earthquakes within 10 km of each section 1 5 20 25 30 3 5 4 5 5 0 60 65 70 75 NE limt of PHS PAC geometry (Nakajima et al 2009) 55 Low-angle thrust-faulting earthquake Offshore refraction survey (Nakahigashi et al 2012;Kono et al 2017) Velocity structure (interval of 0.05°) Fig. 11 Geometries of the upper boundary of the PHS compared to previous study.…”

Section: Upper Boundary and Eastern Limit Of Phsmentioning

confidence: 99%

Configuration and structure of the Philippine Sea Plate off Boso, Japan: constraints on the shallow subduction kinematics, seismicity, and slow slip events

Ito

Tonegawa

Uchida

et al. 2019

Earth Planets Space

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We applied tomographic inversion and receiver function analysis to seismic data from ocean-bottom seismometers and land-based stations to understand the structure and its relationship with slow slip events off Boso, Japan. First, we delineated the upper boundary of the Philippine Sea Plate based on both the velocity structure and the locations of the low-angle thrust-faulting earthquakes. The upper boundary of the Philippine Sea Plate is distorted upward by a few kilometers between 140.5 and 141.0°E. We also determined the eastern edge of the Philippine Sea Plate based on the delineated upper boundary and the results of the receiver function analysis. The eastern edge has a northwest-southeast trend between the triple junction and 141.6°E, which changes to a north-south trend north of 34.7°N. The change in the subduction direction at 1-3 Ma might have resulted in the inflection of the eastern edge of the subducted Philippine Sea Plate. Second, we compared the subduction zone structure and hypocenter locations and the area of the Boso slow slip events. Most of the low-angle thrust-faulting earthquakes identified in this study occurred outside the areas of recurrent Boso slow slip events, which indicates that the slow slip area and regular lowangle thrust earthquakes are spatially separated in the offshore area. In addition, the slow slip areas are located only at the contact zone between the crustal parts of the North American Plate and the subducting Philippine Sea Plate. The localization of the slow slip events in the crust-crust contact zone off Boso is examined for the first time in this study. Finally, we detected a relatively low-velocity region in the mantle of the Philippine Sea Plate. The low-velocity mantle can be interpreted as serpentinized peridotite, which is also found in the Philippine Sea Plate prior to subduction. The serpentinized peridotite zone remains after the subduction of the Philippine Sea Plate and is likely distributed over a wide area along the subducted slab.

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2D spatial distribution of reflection intensity on the upper surface of the Philippine Sea plate off the Boso Peninsula, Japan

et al. 2020

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Geometry and spatial variations of seismic reflection intensity of the upper surface of the Philippine Sea plate off the Boso Peninsula, Japan

Cited by 7 publications

References 41 publications

Tomographic image of crust and upper mantle off the Boso Peninsula using data from an ocean-bottom seismograph array

Tomographic image of crust and upper mantle off the Boso Peninsula using data from an ocean-bottom seismograph array

Configuration and structure of the Philippine Sea Plate off Boso, Japan: constraints on the shallow subduction kinematics, seismicity, and slow slip events

2D spatial distribution of reflection intensity on the upper surface of the Philippine Sea plate off the Boso Peninsula, Japan

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