摘要
根据天水区域构造、高分辨地震折射剖面、大地电磁测深剖面、S波速度结构剖面及新生代火山岩等资料,探讨了天水地区的壳幔结构特征,认为天水地区存在一个大型地幔热隆,进而分析了该区孕震、发震的条件,建立了该区三层次地震构造模式。结合该区历史地震的情况和分布规律,提出天水地震核心区的新概念。地震核心区是根据地震形成机理、地震控制因素的相互关系、历史地震分布规律而圈定出的有研究意义和需要重点监测和预测的地区。该地震核心区确定的依据包括位于两组或多组构造的交点、深部存在地幔热隆、具备孕震和发震的条件和区内发生过历史强震并呈放射状4个要素。核心区边界是在综合地幔热隆规模、形态以及两组构造的宽度、强度的基础上,参考历史地震的分布而圈定的。天水地震核心区的提出是多学科联合科研攻关的实例。天水地震核心区是研究地震形成机理和分布规律的理想基地,同时也是我国地震监测预测工作的重点地区。
This study discussed the crust-mantle structure features of Tianshui area on the basis of regional structure,high resolution seismic refraction profile,magnetotelluric sounding profile,velocity structure profile of S wave and the data of Cenozoic volcanic rocks.It is showed that there is a large mantle hot doming.We established the three-level seismotectonic model in the area through analyzing the seismogenic conditions and proposed a new concept of Tianshui seismic core area according to the situation and distribution of historical earthquakes.Seismic core area is the focal region that demands monitoring and forecasting and it is of great research significance.It is generally delimited by the earthquake forming mechanism,the relationship of earthquake controlling factors and the distribution of historical earthquakes in the area.The supporting reasons for setting the seismic core area include four factors：（1）the area is located at the intersection of two or more structural groups;（2）the existence of deep mantle hot doming;（3）it has sufficient seismogenic conditions;（4）it has strong historical earthquakes which show radial pattern.The boundary of earthquake core area is delimited on the bases of the scales of mantle hot doming,morphology and the width and strength of the two structural groups.The proposal of Tianshui seismic core area is an example of multi-disciplinary scientific research which is unanimously supported by structural geology,petrology,geochemistry and geophysical studies.Tianshui seismic core area has become not only an ideal area of studying the forming mechanism and distribution,but also the priority area of China＇s earthquake monitoring and forecasting.
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2014年第4期293-302,共10页
Earth Science Frontiers
基金
国家"985"创新平台建设项目
关键词
天水
地震核心区
地壳结构
地幔热隆
构造交点
三层次构造模式
Tianshui
seismic core area
crustal structure
mantle thermal uplift
tectonic intersection
three-level tectonic model
