3-D thermal regime and dehydration processes around the regions of slow earthquakes along the Ryukyu Trench

Abstract Several interplate seismic events, such as short-term slow slip events (S-SSEs) and low-frequency earthquakes (LFEs), have been identified in the Ryukyu Trench, southwestern Japan. As one of the specific characteristics of this seismicity, the depths at which S-SSEs occur at the plate inter...

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Autores principales:	Nobuaki Suenaga, Shoichi Yoshioka, Yingfeng Ji
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/bbe6162754764584a101d4b136a2a2da
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spelling	oai:doaj.org-article:bbe6162754764584a101d4b136a2a2da2021-12-02T16:53:01Z3-D thermal regime and dehydration processes around the regions of slow earthquakes along the Ryukyu Trench10.1038/s41598-021-90199-22045-2322https://doaj.org/article/bbe6162754764584a101d4b136a2a2da2021-05-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-90199-2https://doaj.org/toc/2045-2322Abstract Several interplate seismic events, such as short-term slow slip events (S-SSEs) and low-frequency earthquakes (LFEs), have been identified in the Ryukyu Trench, southwestern Japan. As one of the specific characteristics of this seismicity, the depths at which S-SSEs occur at the plate interface beneath Okinawa Island are approximately 5–10 km shallower than those beneath the Yaeyama Islands. To elucidate the cause of this difference in depth, we constructed a three-dimensional, Cartesian thermomechanical subduction model and applied the subduction history of the Philippine Sea (PHS) plate in the model region. As a result, the interplate temperatures at which S-SSEs take place were estimated to range from 350 to 450 °C beneath Okinawa Island and from 500 to 600 °C beneath the Yaeyama Islands. The former temperature range is consistent with previous thermal modelling studies for the occurrence of slow earthquakes, but the latter temperature range is by approximately 150 °C higher than the former. Therefore, explaining how the depth difference in S-SSEs could be caused from the aspect of only the thermal regime is difficult. Using phase diagrams for hydrous minerals in the oceanic crust and mantle wedge, we also estimated the water content distribution on and above the plate interface of the PHS plate. Near the S-SSE fault planes, almost the same amount of dehydration associated with phase transformations of hydrous minerals from blueschist to amphibolite and from amphibolite to amphibole eclogite within the oceanic crust were inferred along Okinawa Island and the Yaeyama Islands, respectively. On the other hand, the phase transformations within the mantle wedge were inferred only beneath the Yaeyama Islands, whereas no specific phase transformation was inferred beneath Okinawa Island around the S-SSE occurrence region. Therefore, we conclude that dehydrated fluid derived from the oceanic crust at the plate interface would play a key role in the occurrence of S-SSEs.Nobuaki SuenagaShoichi YoshiokaYingfeng JiNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-9 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Nobuaki Suenaga Shoichi Yoshioka Yingfeng Ji 3-D thermal regime and dehydration processes around the regions of slow earthquakes along the Ryukyu Trench
description	Abstract Several interplate seismic events, such as short-term slow slip events (S-SSEs) and low-frequency earthquakes (LFEs), have been identified in the Ryukyu Trench, southwestern Japan. As one of the specific characteristics of this seismicity, the depths at which S-SSEs occur at the plate interface beneath Okinawa Island are approximately 5–10 km shallower than those beneath the Yaeyama Islands. To elucidate the cause of this difference in depth, we constructed a three-dimensional, Cartesian thermomechanical subduction model and applied the subduction history of the Philippine Sea (PHS) plate in the model region. As a result, the interplate temperatures at which S-SSEs take place were estimated to range from 350 to 450 °C beneath Okinawa Island and from 500 to 600 °C beneath the Yaeyama Islands. The former temperature range is consistent with previous thermal modelling studies for the occurrence of slow earthquakes, but the latter temperature range is by approximately 150 °C higher than the former. Therefore, explaining how the depth difference in S-SSEs could be caused from the aspect of only the thermal regime is difficult. Using phase diagrams for hydrous minerals in the oceanic crust and mantle wedge, we also estimated the water content distribution on and above the plate interface of the PHS plate. Near the S-SSE fault planes, almost the same amount of dehydration associated with phase transformations of hydrous minerals from blueschist to amphibolite and from amphibolite to amphibole eclogite within the oceanic crust were inferred along Okinawa Island and the Yaeyama Islands, respectively. On the other hand, the phase transformations within the mantle wedge were inferred only beneath the Yaeyama Islands, whereas no specific phase transformation was inferred beneath Okinawa Island around the S-SSE occurrence region. Therefore, we conclude that dehydrated fluid derived from the oceanic crust at the plate interface would play a key role in the occurrence of S-SSEs.
format	article
author	Nobuaki Suenaga Shoichi Yoshioka Yingfeng Ji
author_facet	Nobuaki Suenaga Shoichi Yoshioka Yingfeng Ji
author_sort	Nobuaki Suenaga
title	3-D thermal regime and dehydration processes around the regions of slow earthquakes along the Ryukyu Trench
title_short	3-D thermal regime and dehydration processes around the regions of slow earthquakes along the Ryukyu Trench
title_full	3-D thermal regime and dehydration processes around the regions of slow earthquakes along the Ryukyu Trench
title_fullStr	3-D thermal regime and dehydration processes around the regions of slow earthquakes along the Ryukyu Trench
title_full_unstemmed	3-D thermal regime and dehydration processes around the regions of slow earthquakes along the Ryukyu Trench
title_sort	3-d thermal regime and dehydration processes around the regions of slow earthquakes along the ryukyu trench
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/bbe6162754764584a101d4b136a2a2da
work_keys_str_mv	AT nobuakisuenaga 3dthermalregimeanddehydrationprocessesaroundtheregionsofslowearthquakesalongtheryukyutrench AT shoichiyoshioka 3dthermalregimeanddehydrationprocessesaroundtheregionsofslowearthquakesalongtheryukyutrench AT yingfengji 3dthermalregimeanddehydrationprocessesaroundtheregionsofslowearthquakesalongtheryukyutrench
_version_	1718382883435970560

3-D thermal regime and dehydration processes around the regions of slow earthquakes along the Ryukyu Trench

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