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| Titel |
Seismic discontinuities beneath the Tatun volcano group in northern Taiwan from teleseismic receiver functions |
| VerfasserIn |
Chih-Wei Cheng, Chin-Wu Chen, Ya-Chuan Lai, Cheng-Horng Lin |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250142965
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| Publikation (Nr.) |
 EGU/EGU2017-6649.pdf |
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| Zusammenfassung |
| The Tatun volcano group (TVG) is located in northern Taiwan, near the capital city Taipei
and two nuclear power plants on the northern coast. The TVG was built up mainly during the
last 0.8 to 0.2 Ma, and its last eruption occurred ∼6000 years ago. The TVG is composed of
∼20 volcanic composites, cones and domes. Post volcanic activities, such as hot springs and
gas fumaroles, are abundant and active, and small earthquakes are frequent in this region.
These observations indicate that a magma chamber may still exist beneath the TVG.
However, the extent and depth of the potential magma chamber and associated crustal
structures beneath TVG remain elusive. Although numerous seismic studies have
been dedicated to illuminating the crustal structure beneath Taiwan, the resolution
is insufficient for imaging small-scale features such as TVG, mainly due to the
available spacing of seismic stations. To increase the capacity of monitoring TVG
activities, the Taiwan Volcano Observatory at Tatun (TVO) has been deploying a dense
broadband seismic network in the TVG region. In this study, we analyze waveform data
recorded at 16 TVO seismic stations from 140 magnitude>6.0 teleseismic events
during 2012-2013, generating receiver functions (RF) to detect seismic velocity
discontinuity in the crust and upper mantle beneath TVG. Our preliminary results
show that the crustal structure in this region is likely highly heterogeneous, and the
Moho discontinuity presents significant lateral variation. The crust is thinnest in the
central TVG, manifest in RF with positive pulses (indicating downward velocity
increase) at 1.5-2.5 s. The crust thickens outward to the margins of TVG, as the
times of positive pulses increase to 3-4 s. In addition, pronounced negative pulses
(downward velocity decrease) are observed at times of ∼1-2 s, corresponding to mid- to
lower-crustal depths, which appear to represent a low velocity layer that dips southeasterly
across the TVG region. We further invert the RF signals for velocity models to
investigate the nature and spatial distribution of the low velocity layer beneath the TVG. |
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