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Titolo:
Distribution of magma beneath the Toba caldera complex, north Sumatra, Indonesia, constrained by three-dimensional P wave velocities, seismicity, andgravity data
Autore:
Masturyono; McCaffrey, R; Wark, DA; Roeckere, SW; Fauzi; Ibrahim, G; Sukhyar;
Indirizzi:
Rensselaer Polytech Inst, Dept Earth & Environm Sci, Troy, NY 12181 USA Rensselaer Polytech Inst Troy NY USA 12181 vironm Sci, Troy, NY 12181 USA Meteorol & Geophys Agcy, Jakarta, Indonesia Meteorol & Geophys Agcy Jakarta Indonesia phys Agcy, Jakarta, Indonesia Volcanol Survey Indonesia, Bandung, Indonesia Volcanol Survey Indonesia Bandung Indonesia donesia, Bandung, Indonesia
Titolo Testata:
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
, volume: 2, anno: 2001,
pagine: NIL_1 - NIL_24
SICI:
1525-2027(20010416)2:<NIL_1:DOMBTT>2.0.ZU;2-L
Fonte:
ISI
Lingua:
ENG
Soggetto:
ARC-CONTINENT COLLISION; UPPER-MANTLE P; TELESEISMIC TOMOGRAPHY; NEW-MEXICO; VOLCANIC FIELD; VALLES-CALDERA; DEEP-STRUCTURE; ARRIVAL TIMES; EARTHQUAKE; CRUST;
Keywords:
Magma; Sumatra; tomography; caldera; earthquakes; subduction; lithosphere and upper mantle; volcano seismology; physics and chemistry of magma bodies; Asia;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
48
Recensione:
Indirizzi per estratti:
Indirizzo: Masturyono Rensselaer Polytech Inst, Dept Earth & Environm Sci, Troy, NY 12181 USA Rensselaer Polytech Inst Troy NY USA 12181 Troy, NY 12181 USA
Citazione:
Masturyono et al., "Distribution of magma beneath the Toba caldera complex, north Sumatra, Indonesia, constrained by three-dimensional P wave velocities, seismicity, andgravity data", GEOCH GEO G, 2, 2001, pp. NIL_1-NIL_24

Abstract

We estimate the one- and three-dimensional P wave velocity structure beneath the Toba caldera complex, a 30 X 100 km topographic depression in North Sumatra, using arrival time data of local earthquake recorded by a 40-station seismic network that operated for 4 months. Inversions reveal the presence of P velocities up to 37% below normal that likely map the distribution of magma within this subduction-related volcanic system, considered the world's largest. In the upper 10 km of crust the largest low-velocity region underlies the southern two thirds of the depression and coincides with a gravity low centered over the resurgent dome. A smaller volume of low velocities is observed in the upper crust under the north end of the depression. Separating the two regions is a zone of locally high velocities, indicating that the shallow, subcaldera magma system is composed of two separate reservoirs, not a single one that extends the entire length of the caldera complex. Above each low-velocity region is a postcollapse volcano that erupted mostly mafic lavas after the last major caldera collapse similar to 74 kyr ago. A low-velocity column below one of these volcanoes can be traced into the uppermost mantle and corresponds with a planar distribution of low-frequency earthquakes in the 20- to 40-km-depth range. The low-frequency earthquakes apparently record the migration of melt in the mafic roots of this large-volume, crustal magma system.

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Documento generato il 04/12/20 alle ore 12:48:51