甘肃与邻近地区地震波运动学和动力学特性的某些观测研究及其应用

PRELIMINARY STUDY ON KINEMATIC AND DYNAMIC CHARACTERISTICS OF SEISMIC WAVES IN GANSU AND ITS VICINITY AND THEIR APPLICATIONS

摘要:

木文利用永登地区人工地震资料和九条岭、南坪、松潘天然地震资料研究甘肃及其邻近地区地震波特性。结果表明:在甘肃东部与邻近地区地壳中反射纵波的平均速度是6.21公里/秒,σ_v=0.029公里/秒;河西地区为6.32公里/秒,σ_v=0.016公里/秒。人工地震产生的回折纵波的衰减较天然地震横波快得多。在临界反射区以内,人工地震反射纵波的频率基本上保持稳定,反射波振幅与回折波振幅比A_P11/A_P按距离大体分为三段,每一段随距离变化不太明显。观测结果对于本区地震研究、测震分析有一定参考意义,也为观测震前振幅比异常提供了依据。
在分析速度分布和振幅衰减的基础上,本文认为甘肃及邻近地区地壳模型可取为单层不均匀介质(沉积层除外),本区西部地壳厚度为54公里,东部为50公里,在局部地区为47公里。
为了给今后本区的现测工作积累经验,对野外工作方法和仪器调试作了简要讨论,並编绘f爆破地动速度随宸中距衰减的经验曲线,可供野外工作参考。

Abstract:

In order to study the kinematic and dynamic regional characteritics of seismic waves in the crust and the upper mantle of Gansu Province and its vicinity,we have used a series of data concerning the blasts and some earthquakes.
The results obtained are as follows:
1) The average velocity of the longitudinal wave from M discontinuity is 6.21-6.32 km/sec passing the crust and the upper mantle of Gansu.
2) Inclusive of the relative、thick sendimentary layer,the crustal thickness is 54 km in the west and 50 km in the east of the region,and in the other area it is 47 km.
3) The dominant frequenc of the reflected wave is stable before critic cal reflection.A possible model of the crust about this region is given% roughly.