Seismic Detection of a Magma Reservoir beneath Turtle Island of Taiwan by S-Wave Shadows and Reflections

Abstract Although surface geology, eruption information and clustering seismicity all suggest Turtle Island (Kueishantao) of northern Taiwan is an active volcano, there was no direct evidence to conclude that magma reservoirs exist beneath it. Even less evidence is available to determine their spati...

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Autores principales:	Cheng-Horng Lin, Ya-Chuan Lai, Min-Hung Shih, Hsin-Chieh Pu, Shiann-Jong Lee
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2018
Materias:	Magma Reservoir Turtle Island Compensated Linear Vector Dipole (CLVD) Okinawa Trough Tatun Volcano Group Medicine R Science Q
Acceso en línea:	https://doaj.org/article/7f914e4377b747f4844cd233172b0f21
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spelling	oai:doaj.org-article:7f914e4377b747f4844cd233172b0f212021-12-02T15:08:52ZSeismic Detection of a Magma Reservoir beneath Turtle Island of Taiwan by S-Wave Shadows and Reflections10.1038/s41598-018-34596-02045-2322https://doaj.org/article/7f914e4377b747f4844cd233172b0f212018-11-01T00:00:00Zhttps://doi.org/10.1038/s41598-018-34596-0https://doaj.org/toc/2045-2322Abstract Although surface geology, eruption information and clustering seismicity all suggest Turtle Island (Kueishantao) of northern Taiwan is an active volcano, there was no direct evidence to conclude that magma reservoirs exist beneath it. Even less evidence is available to determine their spatial configuration. If the magma reservoirs are filled by liquids and melt, S-waves are totally reflected and leave behind a shadow, like when passing through the Earth’s outer core. We detect both these S-wave shadows and strong reflections from the surface using earthquakes at different depths and azimuths. These observations identify a km-scale molten-filled volume located beneath Turtle Island. The magmatic nature of the reservoir is supported by the onset of non-double-couple earthquakes with strong CLVD (Compensated Linear Vector Dipole) and ISO (Isotropic) components, which show a tensor crack compatible with some volume changes within the reservoir. Combining these results with two independent 3-D velocity models and aeromagnetic anomalies recorded in Taiwan, a partially-molten ~19% low-velocity volume is estimated in the mid-crust (13–23 km), with spatial uncertainties of ~3 km. The elongated direction approximately follows the strike of the Okinawa trough, indicating that the source of the magma reservoir might be a back-arc opening.Cheng-Horng LinYa-Chuan LaiMin-Hung ShihHsin-Chieh PuShiann-Jong LeeNature PortfolioarticleMagma ReservoirTurtle IslandCompensated Linear Vector Dipole (CLVD)Okinawa TroughTatun Volcano GroupMedicineRScienceQENScientific Reports, Vol 8, Iss 1, Pp 1-12 (2018)
institution	DOAJ
collection	DOAJ
language	EN
topic	Magma Reservoir Turtle Island Compensated Linear Vector Dipole (CLVD) Okinawa Trough Tatun Volcano Group Medicine R Science Q
spellingShingle	Magma Reservoir Turtle Island Compensated Linear Vector Dipole (CLVD) Okinawa Trough Tatun Volcano Group Medicine R Science Q Cheng-Horng Lin Ya-Chuan Lai Min-Hung Shih Hsin-Chieh Pu Shiann-Jong Lee Seismic Detection of a Magma Reservoir beneath Turtle Island of Taiwan by S-Wave Shadows and Reflections
description	Abstract Although surface geology, eruption information and clustering seismicity all suggest Turtle Island (Kueishantao) of northern Taiwan is an active volcano, there was no direct evidence to conclude that magma reservoirs exist beneath it. Even less evidence is available to determine their spatial configuration. If the magma reservoirs are filled by liquids and melt, S-waves are totally reflected and leave behind a shadow, like when passing through the Earth’s outer core. We detect both these S-wave shadows and strong reflections from the surface using earthquakes at different depths and azimuths. These observations identify a km-scale molten-filled volume located beneath Turtle Island. The magmatic nature of the reservoir is supported by the onset of non-double-couple earthquakes with strong CLVD (Compensated Linear Vector Dipole) and ISO (Isotropic) components, which show a tensor crack compatible with some volume changes within the reservoir. Combining these results with two independent 3-D velocity models and aeromagnetic anomalies recorded in Taiwan, a partially-molten ~19% low-velocity volume is estimated in the mid-crust (13–23 km), with spatial uncertainties of ~3 km. The elongated direction approximately follows the strike of the Okinawa trough, indicating that the source of the magma reservoir might be a back-arc opening.
format	article
author	Cheng-Horng Lin Ya-Chuan Lai Min-Hung Shih Hsin-Chieh Pu Shiann-Jong Lee
author_facet	Cheng-Horng Lin Ya-Chuan Lai Min-Hung Shih Hsin-Chieh Pu Shiann-Jong Lee
author_sort	Cheng-Horng Lin
title	Seismic Detection of a Magma Reservoir beneath Turtle Island of Taiwan by S-Wave Shadows and Reflections
title_short	Seismic Detection of a Magma Reservoir beneath Turtle Island of Taiwan by S-Wave Shadows and Reflections
title_full	Seismic Detection of a Magma Reservoir beneath Turtle Island of Taiwan by S-Wave Shadows and Reflections
title_fullStr	Seismic Detection of a Magma Reservoir beneath Turtle Island of Taiwan by S-Wave Shadows and Reflections
title_full_unstemmed	Seismic Detection of a Magma Reservoir beneath Turtle Island of Taiwan by S-Wave Shadows and Reflections
title_sort	seismic detection of a magma reservoir beneath turtle island of taiwan by s-wave shadows and reflections
publisher	Nature Portfolio
publishDate	2018
url	https://doaj.org/article/7f914e4377b747f4844cd233172b0f21
work_keys_str_mv	AT chenghornglin seismicdetectionofamagmareservoirbeneathturtleislandoftaiwanbyswaveshadowsandreflections AT yachuanlai seismicdetectionofamagmareservoirbeneathturtleislandoftaiwanbyswaveshadowsandreflections AT minhungshih seismicdetectionofamagmareservoirbeneathturtleislandoftaiwanbyswaveshadowsandreflections AT hsinchiehpu seismicdetectionofamagmareservoirbeneathturtleislandoftaiwanbyswaveshadowsandreflections AT shiannjonglee seismicdetectionofamagmareservoirbeneathturtleislandoftaiwanbyswaveshadowsandreflections
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Seismic Detection of a Magma Reservoir beneath Turtle Island of Taiwan by S-Wave Shadows and Reflections

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