宁夏及其邻区虚波速度与震源深度分布

本文采用和达法求宁夏五个区的虚波速度,并用各区虚波速度求得1460次地震震源深度,由这些深度的空间分布看出,宁夏地区震源深度由南向北逐渐加深,但几个地震集中的地区各有不同。西海固地区震源分布近似椭球形区域,在15～20公里处夹有不规则的间断面;吴银地区呈现出一条沿北东方向延伸的震源带;吴忠向马三湖地区有一逐渐加深的倾斜带;石咀山及以北地区多为连续的层状分布。由银川至石咀山一线向西北方向展布出一条倾斜面,在该面上有一小震空区。本文还对形成以上震源分布的力源情况进行了初步的讨论。

DISTRIBUTION OF THE VELOCITY OF DASHED WAVES AND THE SOURCE DEPTH IN NINGXIA AND ITS ADJACENT AREA

In this article the velocities of dashed waves of 5 areas in Ningxia have been determinated by wadati''s method.On the basis of the velocities of dashed waves we determinated the seismic source depths related to 1460 times of shock.In the spatial distribution of these depths we find that the depths of seismic source in the region of Ningxia have become deepened gradually from south to north,but there is some difference in several re-gions where the earthquake is centrolized.In the region of Xihaigu the di-stribution of seismic source appears elliptic,and there is an irregular inte-rruption layer in the place of 15-20km,In the region of wuyin there is a source zone which extended northeastwards.In the region from wuzhong to Masanhu a dipping zone deepened gradually is emergent.In the region of Shijushan and its northern area the distribution is continuously la-yered in the main.In the line from Yinchuan to Shijushan there is a cline plane extended northwest,where a small earthquake gap is present.The force source that formed the seismic origin distributions as mentioned abo-ve is discussed in the article too.