2004年苏门答腊大地震激发的T-波

T-phase from the big Sumatra earthquake(2004/12/26)

T-波是由海底地震或者海陆边界俯冲带附近地震激发,并在海洋低速层中传播的声波.2004年12月26日,在印度洋东部印尼苏门答腊岛附近发生MW=9.3级大地震,其产生的能量在印度洋中激发了巨大的海啸,造成了严重的人员伤亡和财产损失,受到了世界科学家们极大的关注.本文从台站（PALK）及台站（DGAR）记录到的地震的信号中,提取出了清晰的高频T-波,并在频率域内分析,最终得到了T-波的频谱已及频率随时间变化图像.另外,通过对大地震时间域和频率域内T-波信号的分析,了解到此次大地震断层破裂过程持续的时间大致为500 s,其间伴随有两次明显的能量释放过程.分析数据表明两次能量释放过程的间隔大致为80～100 s.T-波分析将为推断海洋地震以及海陆边界俯冲带附近地震的特征,提供一种独立的研究手段和方法.

Tertiary （T-） waves are seismically generated acoustic waves that can propagate over great distances in the SOund Fixing And Ranging （SOFAR） channel. On 2004/12/26, big Sumatra earthquake （Mw = 9.3） occurs at the Sumatra island. A huge tsunami excited by the energy from the big Sumatra earthquake causes a great lose, thus a lot of scientists from all over the world pay a lot attention to such big Sumatra earthquake. In this paper, we report the signal of the big earthquake at island stations （PALK） and （DGAR）, and extract the clear T-phase by high pass filter. At the same time, in frequency domain, we obtain the relationship between the spectrogram of the T-phase and the travel time. After the analysis, In addition we obtain the duration of the this Sumatra earthquake is about 500s, including two big energy extracting processes, the time difference between the two big processes is about from 80s to 100s. The study from T-phase will provide us an independent way to study the earthquake, especially the earthquakes occurring at the ocean bottom and subduction zone region.