中国科学技术大学张海江团队的最新研究揭示了中国四川盆地2019年长宁6.0级浅源地震诱发机制的综合地震证据。相关论文于2024年3月11日发表在《地质学》杂志上。

研究人员利用当地和区域地震台站的数据，确定了地震序列的准确位置、速度结构和地震区域超孔隙流体压力。结果表明，此次6.0级地震震源极浅(低于平均海平面约1.6km)，并伴有低V_s和高V_p/V_s值以及流体压力过大，证明是一次流体诱发的地震。

主震可能是最浅的6.0级诱发地震，由注入流体扩散引起的孔隙压力升高、盐穴引起的地层差异沉降，以及富含石英和二氧化硅的高裂缝性易滑动岩石的综合效应引发的。随着来自主震的库仑应力转移，该层序以级联的方式破裂，涉及先前存在的不同倾角的斜断层。

附：英文原文

Title: Comprehensive seismic evidence for the inducing mechanism of extremely shallow 2019 Changning M_s 6.0 earthquake by solution salt mining, Sichuan Basin, China

Author: Uzonna Okenna Anyiam, Jiawei Qian, Yuyang Tan, Haijiang Zhang

Issue&Volume: 2024-03-11

Abstract: In the Changning region of the Sichuan Basin, China, which has experienced decades-long injection of freshwater for commercial salt mining, a M_s 6.0 earthquake occurred in June 2019, along with four M_s >5 aftershocks. Using data from local and regional seismic stations, we determine accurate locations for this earthquake sequence, velocity structures, and excess pore fluid pressures of the source region. Our results show that the M_s 6.0 earthquake is extremely shallow (～1.6 km below mean sea level) and is associated with low Vs and high V_p/V_s values and excess fluid pressures, indicating a fluid-induced earthquake. The mainshock was likely the shallowest M >6.0 induced earthquake, and it was triggered by the combined effect of pore pressure increase from the diffusion of injected fluids, differential formation subsidence from salt caverns, and highly fractured slip-prone rocks enriched in quartz and silica content. Following Coulomb stress transfer from the mainshock, the sequence ruptured in a cascading manner involving preexisting oblique faults of varying dips.

DOI: 10.1130/G51699.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G51699.1/636167/Comprehensive-seismic-evidence-for-the-inducingredirectedFrom=fulltext