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| Titel |
Repetitive fracturing during spine extrusion at Unzen volcano, Japan |
| VerfasserIn |
O. D. Lamb, S. Angelis, K. Umakoshi, A. J. Hornby, J. E. Kendrick, Y. Lavallée |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 6, no. 4 ; Nr. 6, no. 4 (2015-12-07), S.1277-1293 |
| Datensatznummer |
250115528
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| Publikation (Nr.) |
 copernicus.org/se-6-1277-2015.pdf |
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| Zusammenfassung |
| Rhythmic seismicity associated with spine extrusion is a well-documented
phenomenon at a number of dome-forming volcanic systems. At Unzen volcano,
Japan, a 4-year dome-forming eruption concluded with the emplacement of a
spine from October 1994 to February 1995, offering a valuable opportunity to
further investigate seismogenic processes at dome-forming volcanoes. Using
continuous data recorded at a seismic station located close to the dome, this
study explores trends in the seismic activity during the extrusion of the
spine. We identify a total of 12 208 volcano-seismic events in the period
between October 1994 and February 1995. Hourly event counts indicate cyclic
activity with periods of ∼ 40 to ∼ 100 h, attributed to pulsatory
ascent defined by strain localisation and faulting at the conduit margins.
Waveform correlation revealed two strong clusters (a.k.a. multiplets,
families) which are attributed to fracturing along the margins of the
shallow, ascending spine. Further analysis indicates variable seismic
velocities during the spine extrusion as well as migration of the cluster
sources along the spine margins. Our interpretation of the results from
seismic data analyses is supported by previously published field and
experimental observations, suggesting that the spine was extruded along an
inclined conduit with brittle and ductile deformation occurring along the
margins. We infer that changes in stress conditions acting on the upper and
lower spine margins led to deepening and shallowing of the faulting sources,
respectively. We demonstrate that the combination of geophysical, field and
experimental evidence can help improve physical models of shallow conduit
processes. |
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