Structure-controlled asperities of the 1920 Haiyuan M8.5 and 1927 Gulang M8 earthquakes, NE Tibet, China, revealed by high-resolution seismic tomography

• Published in: Scientific reports Vol. 11; no. 1; p. 5090
• Main Authors: Sun, Quan, Pei, Shunping, Cui, Zhongxiong, Chen, Yongshun John, Liu, Yanbing, Xue, Xiaotian, Li, Jiawei, Li, Lei, Zuo, Hong
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 03.03.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 704/2151; 704/4111; Earthquake prediction; Earthquakes; Fault lines; Humanities and Social Sciences; Mechanical properties; multidisciplinary; Science; Science (multidisciplinary); Seismic activity; Tomography; Velocity
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-84642-7

Detailed crustal structure of large earthquake source regions is of great significance for understanding the earthquake generation mechanism. Numerous large earthquakes have occurred in the NE Tibetan Plateau, including the 1920 Haiyuan M 8.5 and 1927 Gulang M 8 earthquakes. In this paper, we obtained a high-resolution three-dimensional crustal velocity model around the source regions of these two large earthquakes using an improved double-difference seismic tomography method. High-velocity anomalies encompassing the seismogenic faults are observed to extend to depths of 15 km, suggesting the asperity (high-velocity area) plays an important role in the preparation process of large earthquakes. Asperities are strong in mechanical strength and could accumulate tectonic stress more easily in long frictional locking periods, large earthquakes are therefore prone to generate in these areas. If the close relationship between the aperity and high-velocity bodies is valid for most of the large earthquakes, it can be used to predict potential large earthquakes and estimate the seismogenic capability of faults in light of structure studies.