Investigation of T-Wave Propagation in the Offshore Area East of Taiwan from Early Analog Seismic Network Observations

  • Author(s): Bor-Shouh Huang, Po-Fei Chen, Yi-Ling Huang, Win-Gee Huang, and Chun-Chi Liu
  • DOI: 10.3319/TAO.2011.03.09.01(T)
  • Keywords: T-wave, Earthquake, Propagation, Analog records, Taiwan



Extant paper records of the early analog seismic network of Taiwan represent a large resource for earthquake studies in several disciplines. In this study, we report on T waves generated from offshore earthquakes, based on analog observations. The T phases were identified from their stable apparent velocity of about 1.5 km s-1 and other observations using data recorded by stations in eastern Taiwan and on two nearby islands. The observed T phases are recorded for the first time from Taiwan, and in particular are observed by the network in the distal range of local earthquakes. Most of the T waves are observed at island stations at epicentral distances greater than 100 km. For earthquakes that occurred a great distance east of Taiwan, the T phases are always the most dominant phases observed at island stations east of Taiwan, and are also seen at some inland stations with smaller amplitudes. No T phases from inland events were observed by stations on Taiwan or on nearby islands. The observations indicate that the amplitude of the T phase is highly attenuated on its land path and that the propagation direction of the T phase is affected by water depth.

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