Integrated seismic exploration in the collision plate boundary of Taiwan

2005年，我们在台湾南部一条150公里长的线路上部署了60台三分量地震仪来观测天然地震。我们记录了当地、区域和远震事件。这些资料显示了地壳的大规模形变，这可能受台湾地区碰撞构造的控制。通过对2005年获得的地震资料进行分析，得到了东西向线下的二维地震速度结构。我们获得的层析图像显示了中央山脉之下的厚重地壳和侵入地壳较浅部分的高速体。我们综合了1999年集集地震的余震观测、2001年台湾观测的数据和其他地球物理数据，这些数据是为规划美国和台湾科学家提出的TAIGER项目而收集的。综合结果显示，整个岩石圈碰撞构造，至少在台湾山区的中部和南部，对了解造山过程是重要的。碰撞构造对2004年新泻县中期地震等日本内陆地震具有重要意义。我们比较了台湾和日本的地震和构造。

We deployed 60 3-component seismographs along a 150-km-long line in the southern part of Taiwan to observe natural earthquakes in 2005. We have recorded local, regional and teleseismic events. The data show large-scale deformation of the crust, which might be controlled by the collision tectonics in Taiwan. A highly active seismic activity was detected in central part of the east-west line indicating intra seicmic activity.We analyzed the seismic data that we acquired in 2005 to obtain a two-dimensional seismic velocity structure under the east-west line. The tomogram that we obtained shows a thick crust beneath the central mountains and a high velocity body intruding to a shallower part of the crust.We integrated the data form the observation of aftershocks of the 1999 Chi-Chi earthquake, those of the 2001 observation in Taiwan, and other geophysical data, which are collected to plan the TAIGER project proposed by the US and Taiwan scientists. We discussed the results in the TAIGER work shop held in Taiwan.The integrated results indicate that the whole lithospheric collision tectonics is, at least the central and southern part of Taiwan mountain areas, important to understand the mountain building process. The collision tectonics has important implication to the Japanese in-land earthquakes such as the 2004 mid-Niigata prefecture earthquake. We compared earthquakes and tectonics in Taiwan and Japan.