利用大地观测台网对1992年6月28日兰德斯地震破裂过程的研究

使用正演点源求和技术对大地观测台网记录到的1992年6月28日兰德斯地震(M_W7.3)的位移地震图进行了决定性的模拟。虽然数据组是稀少的,但仍能有力地确定主要的破裂参数,例如,总滑动分布、破裂速度、上升时间和总的震源持续时间。如能得到本区合适的格林函数表,则本比较简单的方法适于大震后的快速跟踪使用。用来模拟兰德斯主震的断层具有沿走向70km的长度和沿倾斜方向15km的宽度。我们找到了一个模型,其在地表的滑动范围和幅度与观测到的表面滑动是一致的,并提供了对地震数据拟合非常好的参考。从地震方面来讲,兰德斯地震其特点为由两个小一点的地震所组成。第一个小震的最大滑动是在震中以北10km,而第二个小地震是沿断层走向在震中西北40km处。地震矩分布分别为,第一个地震是2×10^(26)dyne-cm(1 dyne-cm=10^(-7)Nm);第二个地震是6×10^(26)dyne-cm。在我们的模型中假设地震矩的分布沿走向并在各种深度是相同的。这个假设意味着,由于速度模型中材料性质的不同使得在深处的滑动是地表滑动的69％。震源模型对破裂速度和错位上升时间的灵敏度是经过检验的。我们发现2.9km/s的破裂速度(剪切波速度的80％)和1-3s的上升时间是与数据适合的。上升时间只是24s总的震源过程的一小部分,这意味着断层的滑动发生在一个很窄的地带上(3到10km),滑动会发生在整个破裂过程中的任何一个瞬间。

Seismic Monitoring Network and Seismic Activities in Thailand

The details of seismic monitoring network and seismological work in Thailand, including some information on felt earthquakes that occurred from 2000 to August 2001, are reported here.

Preliminary Study on the Relationship between the M_s8.0 Wenchuan Earthquake of 2008 and the Anomalies of Earth Resistivity Observed at Qingdao Seismic Station

Near-surface earth resistivity and underground water level anomalies were recorded at Qingdao seismic observatory of Shandong Province before and after the MS8.0 Wenchuan Earthquake of May 12,2008.The observed data of earth resistivity at the observatory revealed that the underground water level dropped and the resistivity increased.It is postulated that in the special tectonic setting at Qingdao observatory,the variation of stress and strain caused the change of water level beneath the station,thus,leading to the variation of earth resistivity.The relationship between the variation of stress field and the change of earth resistivity before earthquake is analyzed.