Arc-arc collision caused the 2018 Eastern Iburi earthquake (M 6.7) in Hokkaido, Japan

Hua, Yilei; Zhao, Dapeng; Xu, Yixian; Wang, Zewei

doi:10.1038/s41598-019-50305-x

Cited by 25 publications

(10 citation statements)

References 57 publications

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“…The forearc mantle with a low‐V anomaly is only observed in the collision zone of the Kuril arc with the Honshu arc (iii in Figure and III‐III′ in Figure S8), indicating that more water from the subducting slab has entered into the overlying mantle wedge there (e.g., Gou et al, ; Hua et al, ). It is also possible that the low‐V anomaly reflects delamination of the lower crust from the base of the upper plate and sinking to the upper mantle (e.g., Gou et al, ; Ito, ; Kita et al, ; Koulakov et al, ; Niu et al, ).…”

Section: Discussionmentioning

confidence: 99%

Seismic Evidence for Water Transportation in the Forearc off Northern Japan

Zhao

2020

JGR Solid Earth

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The water cycle plays an essential role in arc volcanism, earthquake generation, mantle rheology, and thermal structure of subduction zones. Previous seismic studies have revealed strong structural heterogeneities in the megathrust zone in Northeast Japan and Hokkaido. However, water transportation in the forearc region remains poorly understood due to the lack of long-term seismic observatories at the seafloor. Using high-quality data recently recorded by the permanent ocean-bottom-seismometer network (S-net) in the Pacific Ocean off Northern Japan, we study the fine three-dimensional P wave velocity (V p ) structure of the crust and upper mantle beneath the Kuril and Tohoku forearc region. Our results reveal high velocities in the mantle-wedge corner, implying a low degree of serpentinization there. We suggest that the forearc mantle in the study region is cold and anhydrous. The slab interface under the forearc area may have a low permeability, which controls the fluid flux to the mantle wedge and the overriding plate. A low-V p layer atop the subducting Pacific plate is interpreted as the subducted oceanic crust. Dehydration of the subducted oceanic crust occurs at depths of 80-120 km, providing a large volume of water to the overriding mantle wedge to produce arc volcanoes, and part of the water may migrate upward to the shallow area. Large megathrust earthquakes (M w ≥ 6.0) mainly occurred around low-V p patches in the megathrust zone. Destruction of the low-permeability slab interface would result in fluid flow upward, which may trigger large megathrust earthquakes and seismicity in the mantle wedge under the forearc.

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Section: Discussionmentioning

confidence: 99%

Seismic Evidence for Water Transportation in the Forearc off Northern Japan

Zhao

2020

JGR Solid Earth

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“…This process can induce structural and compositional evolution in fault zones and finally trigger intraslab earthquakes, which may accompany changes of seismic velocity and Poisson's ratio as our results revealed. Furthermore, the excluded fluids can migrate upward to the mantle wedge and the overriding crust, probably triggering shallow inland earthquakes as revealed in some fore‐arc areas (e.g., Gou et al, ; Hua et al, ; Tong et al, ; Zhao et al, ).…”

Section: Discussionmentioning

confidence: 99%

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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“…After spot selection based on CL and BSE images, the analyses were completed using a Thermo Fisher Elemen-tXR ICP-MS, coupled with a Photon-Machines Analyte G2 193 nm excimer laser, with a wavelength of 193 nm. U, Th and Pb concentrations were calculated in relation to the reference zircon GJ-1 (Jackson et al, 2004). Isotope ratios were normalized to the same reference zircon.…”

Section: Appendix Bmentioning

confidence: 99%

The Piuquencillo fault system: a long-lived, Andean-transverse fault system and its relationship with magmatic and hydrothermal activity

Piquer

Rivera²,

Yáñez

et al. 2021

Solid Earth

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Abstract. Lithospheric-scale fault systems control the large-scale permeability in the Earth's crust and lithospheric mantle, and its proper recognition is fundamental to understand the geometry and distribution of mineral deposits, volcanic and plutonic complexes and geothermal systems. However, their manifestations at the current surface can be very subtle, as in many cases they are oriented oblique to the current continental margin and to the axis of the magmatic arc; be partially obliterated by younger, arc-parallel faults; and also be covered by volcanic and sedimentary deposits, through which the fault might propagate vertically. The Piuquencillo fault system (PFS) is a proposed lithospheric-scale fault system, located in the Main Cordillera of central Chile. Here, we present the results of the first detailed field study of the PFS, based on structural data collected at 82 structural stations distributed across all the western Main Cordillera. The first published U–Pb zircon ages for the La Obra batholith, which is bounded to the south by the PFS but also affected by younger reactivations of it, were obtained. They yielded 20.79 ± 0.13 Ma (granodiorite) and 20.69 ± 0.07 Ma (monzogranite). Statistical analysis of fault-plane data shows that the presence of the PFS is reflected on a strong preferred NW to WNW strike, with variable dip directions, evident from the analysis of the total fault-plane population and also from individual segments of the PFS. In some segments, the presence of major NE- to ENE-striking faults which intersect the PFS is also reflected in the preferred orientation of fault planes. Preferred orientations of hydrothermal veins, breccias and dikes show that both the PFS and some ENE-striking faults were capable of channelling hydrothermal fluids and magma. Kinematic and dynamic analysis of fault-plane data reveals that most of the PFS was reactivated with sinistral ± reverse kinematics during the Neogene, under a strike-slip to transpressive regime with E- to ENE-trending shortening direction (σ1). Detailed kinematic and dynamic analyses were completed for various segments of the PFS and also for the different rock units affected by it. This study supports the concept that the PFS is a lithospheric-scale fault system, which strongly controlled deformation and the flow of magmas and hydrothermal fluids during the Neogene. The PFS forms part of a larger, margin-transverse structure, the Maipo deformation zone, a continental-scale discontinuity which cut across the entire Chilean continental margin and has been active at least since the Jurassic.

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Arc-arc collision caused the 2018 Eastern Iburi earthquake (M 6.7) in Hokkaido, Japan

Cited by 25 publications

References 57 publications

Seismic Evidence for Water Transportation in the Forearc off Northern Japan

Seismic Evidence for Water Transportation in the Forearc off Northern Japan

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

The Piuquencillo fault system: a long-lived, Andean-transverse fault system and its relationship with magmatic and hydrothermal activity

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