Gravity variations preceding the large earthquakes in the Qinghai-Tibet Plateau from 21st century

作者：Yiqing Zhu, Yong Zhang, Guoqing Zhang, Fang Liu, Yunfeng Zhao · 发表于：Chinese Science Bulletin (Chinese Version) · 年份：2020 · DOI：10.1360/tb-2019-0153 · 被引用次数：14 · 研究领域：earthquake and tectonic studies、Geological and Geophysical Studies、Earthquake Detection and Analysis

Since the beginning of 21st century, there have been 7 large earthquakes in the Qinghai-Tibet Plateau: The Kunlun Mountain Pass M s8.1 earthquake in 2001, the Wenchuan M s8.0 earthquake and the Yutian M s7.3 earthquake in 2008, the Yushu M s7.1 earthquake in 2010, the Lushan M s7.0 earthquake in 2013, the Yutian earthquake M s7.3 in 2014, and the Jiuzhaigou M s7.0 earthquake in 2017. Prior to these earthquakes, the China Earthquake Administration (CEA) had gathered mobile gravity observations over several periods near the epicenter region, obtaining reliable gravity change with time data. In this study, the relationship between gravity variation and these 7 large earthquakes was analyzed using the absolute and relative gravity observations. The results revealed that: (1) The gravity variation fields related to the occurrence of these earthquakes were in response to the movement and change of underground fluid distributed deep in the crust. An enhanced regional stress field leads to deep material migration and transformation, which results in large-scale regional gravity change. (2) Large earthquakes tend to occur in the high-gradient transition zones between positive and negative gravity anomaly regions associated with the boundary of tectonic active blocks. The inflection point of the gravity change isoline is the transition zone between increasing and decreasing material density. The difference in the motions of the increasing and decreasing material is intense, and ...