利用重力/GPS联合观测数据计算地壳垂向构造应力的新方法  

A new method for computing the vertical tectonic stress of the crust by use of hybrid gravity and GPS data

作　　者：高尚华[1] 佘雅文[1] 付广裕[1] 

机构地区：[1]中国地震局地震预测重点实验室(中国地震局地震预测研究所),北京100036

出　　处：《地球物理学报》2016年第6期2006-2013,共8页Chinese Journal of Geophysics

基　　金：国家自然科学基金(41574071;41404142;41461164004);地震预测研究所基本科研业务费专项(2014IES010102;2014IES0201)资助

摘　　要：本文提出一种基于重力/GPS联合观测数据计算垂向构造应力的新方法.计算步骤如下:(1)通过重力/GPS联合观测数据计算布格重力异常;(2)依据布格重力异常数据推算莫霍面深度;(3)依据GPS观测数据,通过均衡理论计算均衡面深度;(4)依据莫霍面与均衡面之间剩余物质(壳幔物质密度差)所承受的附加浮力,计算地壳承载的垂向构造应力.本文利用上述构造应力新算法,计算了巴颜喀拉块体东边界及周边地区垂向构造应力分布,发现龙泉山断裂带以东地区垂向构造应力基本为零,龙泉山断裂带与龙门山断裂带之间地区垂向构造应力为正值,巴颜喀拉地块东部垂向构造应力为负值.鲜水河断裂带东南段周边蓄积了-40^-50 MPa的垂向构造应力,且梯度变化剧烈;松潘高原蓄积的垂向构造应力大约为-10^-20 MPa,相对较小.This paper presents a new method to calculate the vertical tectonic stress of the crust by use of hybrid gravity and GPS observation data.The calculation procedures are as follows：（1）Compute the Bouguer gravity anomalies using gravity and GPS data;（2）Deduce the Moho depths using the obtained Bouguer gravity anomaly data;（3）Compute the isostatic crustal thickness based on isostatic theory and GPS data;（4）Calculate the vertical tectonic stress of the crust based on the buoyancy that the remaining materials between the Moho and the isostatic crustal thickness bears.Using the above method,we calculate the vertical tectonic stress at the east boundary of Bayanhar block and surrounding area.The vertical tectonic stress is about zero at the area east to the Longquanshan fault zone,positive at the area between the Longmenshan and Longquanshan fault zones,and negative at the eastern part of Bayanhar block.The vertical tectonic stress at the southeast segment of the Xianshuihe fault and adjacent area is as high as-（40-50）MPa,with rapid gradient changes.The vertical tectonic stress at Songpan Plateau is-（10-20）MPa,lower than that of Xianshuihe area.

关 键 词：重力 布格重力异常 构造应力 地壳均衡 莫霍面 

分 类 号：P313[天文地球—固体地球物理学] P223[天文地球—地球物理学]