Microseismicity and faulting in the southwestern Okinawa Trough

Jing Yi Lin, Jean Claude Sibuet, Chao Shing Lee, Shu Kun Hsu, Frauke Klingelhoefer, Yves Auffret, Pascal Pelleau, Jacques Crozon, Cheng Horng Lin

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

In November 2003, 15 ocean bottom seismometers were deployed in the southwestern Okinawa Trough. More than 3300 microearthquakes were located during the 10-days passive seismic experiment. The earthquake activity is characterized by the ceaseless occurrence of small earthquakes in the vicinity of all the instruments. The seismicity is essentially restricted to the central part of the Southwestern Okinawa Trough, except for one cluster of events situated in the southern part of it (cluster 2). The seismic activity terminates abruptly against the NE-SW trending prolongation of the Lishan fault. Most of the microearthquakes are aligned along the E-W trending normal faults, showing where the present-day active normal faulting occurs and how it accounts for the N-S extension in the Okinawa Trough. According to the P-wave velocity spectra estimated from some deep earthquakes located beneath the cross backarc volcanic trail area, the existence of a lower crustal/upper mantle magma chamber is confirmed by the presence of low frequency earthquakes in the 3-10 Hz bandwidth.

Original languageEnglish
Pages (from-to)268-280
Number of pages13
JournalTectonophysics
Volume466
Issue number3-4
DOIs
StatePublished - 10 Mar 2009

Keywords

  • Backarc basin
  • Cross backarc volcanic trail
  • Extension
  • Microseismicity
  • Normal faulting
  • Southwestern Okinawa Through

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