論文

査読有り
2020年2月

Reliability evaluation of volcanic tremor source location determination using cross-correlation functions

GEOPHYSICAL JOURNAL INTERNATIONAL
  • Theodorus Permana
  • ,
  • Takeshi Nishimura
  • ,
  • Hisashi Nakahara
  • ,
  • Eisuke Fujita
  • ,
  • Hideki Ueda

220
2
開始ページ
1300
終了ページ
1315
記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.1093/gji/ggz523
出版者・発行元
OXFORD UNIV PRESS

Source location determination of volcanic tremor has been a challenge in seismology due to the waveform complexity and difficulties in reading P- and S-wave arrival times. We present a method for locating volcanic tremor recorded at a seismic network distributed around a volcano. The method combines the source-scanning algorithm and cross-correlation analysis. Tremor records are processed using a technique adopted from ambient seismic interferometry to obtain stacked cross-correlation functions (CCFs) for all station pairs, which are expected to show high amplitudes at the lag time that corresponds to the traveltime difference between the stations. The best seismic source location is determined from the maximum of the sum of envelope amplitudes of CCFs at predicted traveltime differences between all pairs of stations. This method does not compute theoretical amplitudes, assume an initial hypocentre location or measure the arrival times. To quantitatively evaluate the accuracy of the location determination, we examine the method by using the vertical component seismic data of volcano-tectonic (VT) earthquakes recorded at six seismic stations at Izu-Oshima volcano. The VTs have been previously located by using arrival times of P and S waves, and the hypocentres are used as the reference for evaluation and error estimation of the method. The results show that the misfit, which is the distance between our estimated sources and the references, is about 2 km or less when using CCFs at the frequency band of 4-16 Hz which contains the dominant frequencies of direct S waves. To test whether the method can be used for volcanic tremor, we simulate the tremors by combining the observed VTs that occurred randomly in time in a localized region. The simulated tremors are determined with location errors of approximately 1 km or less, when the sources of VTs are located within a distance of 1 km and CCFs are calculated for a minimum data length of about 2 min. The volcanic tremor location method we present here can be used as an alternative tool for volcano monitoring, especially to locate tremors and seismic events with no clear phase arrival.

リンク情報
DOI
https://doi.org/10.1093/gji/ggz523
Web of Science
https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:000506848400038&DestApp=WOS_CPL
ID情報
  • DOI : 10.1093/gji/ggz523
  • ISSN : 0956-540X
  • eISSN : 1365-246X
  • Web of Science ID : WOS:000506848400038

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