Slab dehydration and earthquake distribution beneath southwestern and central Japan based on three‐dimensional thermal modeling

• Published in: Geophysical research letters Vol. 44; no. 6; pp. 2679 - 2686
• Main Authors: Ji, Yingfeng, Yoshioka, Shoichi
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28.03.2017
• Subjects: 3‐D; Amphibolites; Cellular convection; Convection; Dehydration; Distribution; Earthquakes; Free convection; geodynamics; geophysics; Japan; Low temperature; Mathematical models; Moisture content; Phase transitions; Plate tectonics; Plates (tectonics); Seismic activity; Seismology; slab; Slabs; Subduction; Subduction (geology); Tectonics; Temperature; Temperature gradients; thermal; Thermal analysis; Thermal convection; Thermal models; Three dimensional models; Tremors; Water content; Philippine Sea; Japan; ISEW, Philippine Sea; INW, Japan, Shikoku; Japan, Honshu, Mie Prefect., Tokai District; Philippine Sea Plate
• DOI: 10.1002/2016GL072295
• ISSN: 0094-8276

We developed a 3‐D thermal convection model to estimate the thermal regime, water content distribution, and slab dehydration beneath southwestern and central Japan, where deep tectonic tremors and short‐term slow slip events (S‐SSEs) are frequently observed on the plate interface extending from the western Shikoku to the Tokai district. The results showed that the pressure‐temperature (P‐T) conditions for the S‐SSEs, deep tectonic tremors, and regular earthquakes indicate that they probably originated from slab dehydration in association with subduction, resulting in a phase transformation from prehnite‐actinolite/lawsonite blueschist to amphibolite with a large thermal gradient. Slab dehydration and the thermal gradient in the dip direction are considered key factors for controlling the seismogenesis of slow and regular earthquakes in the Philippine Sea plate beneath southwestern and central Japan, although the deep tectonic tremors are more complicated because they are likely favored by a comparatively low temperature gradient in southwestern Japan. Key Points A correspondence between slab dehydration and earthquakes distribution beneath SW and central Japan was identified The occurrence of tectonic tremors and deep SSEs in SW Japan also relate to the interface with high slab dehydration The 3‐D modeling method for slab dehydration distribution is a new subject in this research field