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Crustal structure imaging of multi-geophysical parameters and generating mechanisms of large earthquakes in North-South Seismic Zone
Hu, YP; Wang, Z; Liu, GN; Liu, CX; Fu, Y; mike-wang@souhu.com
2017
发表期刊CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION
卷号60期号:6页码:2113-2129
摘要Crustal structures of multi-geophysical parameters are imaged with high resolution in the North-South Seismic Zone (NSSZ) by inverting a combined dataset of a large number of arrival-time data of P- and S-waves. Based on the high-resolution seismic images we focus on discussing generation mechanism of the large crustal earthquake (M>7. 0) along the NSSZ. Our study revealed that the 1976 Songpan-Pingwu earthquake (M7. 2), 2008 Wenchuan earthquake (M8. 0) and 2013 Lushan earthquake (M7. 0) occurred in the high velocity areas with low Poisson's ratio anomalies. We consider that there could be a close relation between the generation of these three large earthquakes and the crustal deformation caused by intrusive fluids. On the contrary, the 1955 Luhuo earthquake (M7. 4) and the 1973 Kangding earthquake (M7. 1) occurred in Xianshuihe fault zone and their hypocenters were located in the low-velocity areas with high Poisson's ratio anomalies. This might be interpreted as upwelling fluids from the lower crustal channel flow. The surrounding areas of these earthquake hypocenters show strong variations of anomalous high-velocity and high Poisson's ratio, high-velocity and low Poisson's ratio anomalies, and low-velocity and low Poisson's ratio perturbations. These anomalies could be possibly and respectively corresponding to fluid-filled cracked rock, old and steady craton and growing metamorphous rocks along their corresponding faults. The intrusive fluids could initiate large crustal earthquakes by both changing the stress condition on the fault plane and weakening the mechanical strength of the rock matrix. The 1970 Tonghai earthquake (M7. 1) in Yunnan occurred on the Qujiang fault near Ailaoshan-Honghe fault zone. The hypocenter of this earthquake is located in a distinctive boundary where the seismic velocity changes dramatically from low to high whilst the Poisson's ratio varies from high to low across the suture zone. We considered that the crustal strain energy accumulation after fluid extrusion from the lower crust led to the brittle fracture of the source rock hence the Tonghai earthquake. Therefore, we conclude that the strong crustal deformation and intrusive fluids from lower crust could have played major roles in active seismicity and generation of large crustal earthquakes in the NSSZ.
部门归属[Hu Ya-Ping; Wang Zhi; Liu Guan-Nang] Chengdu Univ Technol, Minist Educ, Key Lab Earth Explorat & Informat Tech, Chengdu 610059, Peoples R China; [Wang Zhi; Fu Yi] Chinese Acad Sci, South China Sea Inst Oceanol, Key Lab Ocean Marginal Sea Geol, Guangzhou 510301, Guangdong, Peoples R China; [Liu Cun-Xi] Yalong River Hydropower Dev Co Ltd, Chengdu 610051, Peoples R China
关键词North-south Seismic Zone Seismic Tomography Large Crustal Earthquakes Generating Mechanism Of Earthquake Crustal Structural Imaging
资助项目MSG
文献类型期刊论文
条目标识符http://ir.scsio.ac.cn/handle/344004/16509
专题中科院边缘海地质重点实验室
通讯作者mike-wang@souhu.com
推荐引用方式
GB/T 7714
Hu, YP,Wang, Z,Liu, GN,et al. Crustal structure imaging of multi-geophysical parameters and generating mechanisms of large earthquakes in North-South Seismic Zone[J]. CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION,2017,60(6):2113-2129.
APA Hu, YP,Wang, Z,Liu, GN,Liu, CX,Fu, Y,&mike-wang@souhu.com.(2017).Crustal structure imaging of multi-geophysical parameters and generating mechanisms of large earthquakes in North-South Seismic Zone.CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION,60(6),2113-2129.
MLA Hu, YP,et al."Crustal structure imaging of multi-geophysical parameters and generating mechanisms of large earthquakes in North-South Seismic Zone".CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION 60.6(2017):2113-2129.
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