Applications of satellite gravity missions in co-seismic gravity and geoid changes

本项目主要从以下几个方面进行理论研究：1.研究是否可以从太空探测到大地水准面和重力同频变化，即卫星重力任务。本文在考虑卫星空间分辨率的基础上，考虑了大地震引起的全球形变。在此基础上，提出了一种利用卫星重力观测数据确定位错勒夫数的方法。2.提出了球形地球同震应变变化的新理论。通过比较半空间位错引起的同震形变和均匀球面模型、均质球面和层状球面模型中位错引起的同震变形，研究了地球曲率和径向不均匀的影响。据悉，这两种影响都很大。3.利用超导重力台网成功探测到了2002年北海道地震引起的亚微米GAL同震重力变化，并用Sun和Okubo的位错理论进行了较好的解释。4.该项目还研究了2004年苏门答腊岛地震引起的同震位移、重力和大地水准面变化。上述结果已在日本大地测量会议、日本地球科学联盟大会、动力行星会议和美国地球物理联盟大会上发表。目前已在《地球物理研究》、《地球物理研究通讯》、《科学》等国内外期刊上发表了9篇论文。

This project is mainly about theoretical research on the following aspects: 1. to investigate whether or not co-seismic geoid and gravity changes detectable from space, i.e., the satellite gravity missions. In this study, global deformations caused by large earthquakes are considered with taking satellite spatial resolution into account. Then based on the result, a method to determine Dislocation Love Numbers using the data observed by satellite gravity missions are presented. 2. New theory on co-seismic strain changes for a spherical earth is presented. The effects of the Earth's curvature and radial heterogeneity are also investigated through comparing the co-seismic deformations caused by dislocations in half-space and homogeneous spherical earth models, a homogeneous sphere and a layer spherical model. It was learnt that both the effects are large. 3. The sub-micro gal co-seismic gravity changes caused by the 2002 Hokkaido earthquake were successfully detected by superconducting gravity network, and is well explained by Sun and Okubo's dislocation theory. 4. This project also investigated co-seismic displacement, gravity and geoid changes caused by the 2004 Sumatra earthquake. The above results have been presented in Japanese Geodetic Conferences, The Japanese Geosciences Union Assembly, the Dynamic Planet Conference, and America Geophysical Union Assembly. In summary, there are 9 papers have been published in internal and international journals, such as, Journal of Geophysical Research, Geophysical Research Letter, Science, and so on.