Subduction of thick oceanic plateau and high‐angle normal‐fault earthquakes intersecting the slab
| Autor: | Ryuta Arai, Tomoaki Yamada, Yoshiyuki Kaneda, Mitsuhiro Oikawa, Azusa Nishizawa, Tsutomu Takahashi, Shuichi Kodaira, Seiichi Miura |
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| Rok vydání: | 2017 |
| Předmět: |
geography
geography.geographical_feature_category 010504 meteorology & atmospheric sciences Subduction Seamount Oceanic plateau Geophysics Fault (geology) 010502 geochemistry & geophysics 01 natural sciences Seismic tomography Depth of focus (tectonics) Intraplate earthquake General Earth and Planetary Sciences Seismology Geology Aftershock 0105 earth and related environmental sciences |
| Zdroj: | Geophysical Research Letters. 44:6109-6115 |
| ISSN: | 1944-8007 0094-8276 |
| Popis: | The role of seamounts on interplate earthquakes has been debated. However, its impact on intraslab deformation is poorly understood. Here we present unexpected evidence for large normal-fault earthquakes intersecting the slab just ahead of a subducting seamount. In 1995, a series of earthquakes with maximum magnitude of 7.1 occurred in northern Ryukyu where oceanic plateaus are subducting. The aftershock distribution shows that conjugate faults with an unusually high dip angle of 70-80° ruptured the entire subducting crust. Seismic reflection images reveal that the plate interface is displaced over 1 km along one of the fault planes of the 1995 events. These results suggest that a lateral variation in slab buoyancy can produce sufficient differential stress leading to near-vertical normal-fault earthquakes within the slab. On the contrary, the upper surface of the seamount (plate interface) may correspond to a weakly-coupled region, reflecting the dual effects of seamounts/plateaus on subduction earthquakes. |
| Databáze: | OpenAIRE |
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