The ground motion attenuation models for PGA,PGV and response spectrum at rock sites and soils sites are derived separately from the digital strong motion records of moderate earthquakes in the Sichuan-Yunnan region a...The ground motion attenuation models for PGA,PGV and response spectrum at rock sites and soils sites are derived separately from the digital strong motion records of moderate earthquakes in the Sichuan-Yunnan region after 2007. By comparison with Yu Yanxiangs attenuation model for rock sites in western China,reliability of the model is verified for moderate earthquake. According to the distribution of strong motion data against magnitude and epicentral distance,the applicability and reliability of the results in this paper are discussed.展开更多
By using the teleseismic receiver function method, this paper analyzes the crustal thickness and Vp/Vs ratios beneath the 4 National seismic stations （KMI, TNC, CD2 and PZH） in the Sichuan-Yunnan area. This study gi...By using the teleseismic receiver function method, this paper analyzes the crustal thickness and Vp/Vs ratios beneath the 4 National seismic stations （KMI, TNC, CD2 and PZH） in the Sichuan-Yunnan area. This study gives the variance of Moho depths and velocity ratios of the 4 stations in different directions. The results show that the Moho depth beneath the Kunming station is around 50km, and the vdocity ratio varies between 1.62 and 1.69. The thickness of crust and the velocity ratio do not change much with the direction. The crust beneath Tengchong station shows clear directivity, being 40.7km thick in the northeast and 49.7km thick in the southeast. The difference of the Vp/Vs values is remarkable between the two directions, reaching 0.2. The Chengdu station also has shallow Moho, about 40km, but is 8km deeper in the northeast and southwest and the vdocity ratio has a change of 0.13 between the two directions. The crust beneath the Panzhihua station is stable. In all directions, the Moho depth is around 60km and the Vp/Vs ratio doesn＇t change significantly.展开更多
In this paper,the long time series data of the well water-level data of 12 wells in the Sichuan and Yunnan area is analyzed by the Baytap-G tidal analysis software,and well water level tidal response characteristic pa...In this paper,the long time series data of the well water-level data of 12 wells in the Sichuan and Yunnan area is analyzed by the Baytap-G tidal analysis software,and well water level tidal response characteristic parameters( amplitude ratio and phase change)are extracted. We analyzed the features of the shape and stage change,and characteristic parameters of the tidal response of well water level before and after the earthquakes,which can provide a new method and approach to analyzing the response relationships between well water level and earth tide and barometric pressure. The results show that Luguhu Well and 9 other wells are affected by earth tides,and their well water level amplitude ratios and phases are relatively stable; the Nanxi Well and Dayao Well water level changes are affected by the barometric pressure combined with tide force,and their well water level amplitude ratios and phases are more discrete. The water level amplitude ratios and phases of Jiangyou Well,Luguhu Well and Dongchuan Well are significant to large earthquakes,and the relationship between seismic energy density and water level amplitude ratios and phases of M_2 wave of the three wells are presented.展开更多
The Wenchuan earthquake occurred near the "triple junction" linking the Bayan Har block, the South China block, and the Sichuan-Yunnan rhombic block, and its influences on the surrounding blocks and the main...The Wenchuan earthquake occurred near the "triple junction" linking the Bayan Har block, the South China block, and the Sichuan-Yunnan rhombic block, and its influences on the surrounding blocks and the main fault zones in the Sichuan-Yunnan region, i.e., the block boundary zone, cannot be ignored. In this paper, changes of movement and stress of the fault zones before and after a strong earthquake were simulated based on the GPS repetition survey results recently obtained during 1999–2007, 2009–2011, and 2011–2013 with a two-dimensional finite-element contact model and the "block- loading" method. The results show that, before the Wenchuan earthquake, the movement of the Longmenshan fault zone was very slow and its compressive stress accumulated rapidly; after the Wenchuan earthquake, movements toward the E-SSE direction of the Bayan Har, southwestern Yunnan, and rhombic blocks were enhanced, and the dextral and horizontal compressive speeds and annual accumulative compressive stress of the Longmenshan fault zone increased markedly by factors of 4.5, 2.1, and 2.5, respectively. The southern Xianshuihe, Anninghe, Zemuhe, Daliangshan, and Lijiang-Xiaojinhe fault zones accumulated compressive stress rapidly, forming enhanced compressive stress zones along a NE strike crossing the central part of the Sichuan-Yunnan region. The tensional movement of the Xianshuihe fault zone was enhanced and the slip movement in the central part of the zone was reversed in a short time. The changes are tightly related to the medium-intensity earthquakes that occurred during the same period in this region, revealing that the spatial migration of seismic activity is related to changes of movement of the blocks.展开更多
基金sponsored jointly by the special fund for basic research and operating expenses of Institute of Crustal Dynamics,CEA(ZDJ2013-04)"National Nature Science Foundation of China(51278469)
文摘The ground motion attenuation models for PGA,PGV and response spectrum at rock sites and soils sites are derived separately from the digital strong motion records of moderate earthquakes in the Sichuan-Yunnan region after 2007. By comparison with Yu Yanxiangs attenuation model for rock sites in western China,reliability of the model is verified for moderate earthquake. According to the distribution of strong motion data against magnitude and epicentral distance,the applicability and reliability of the results in this paper are discussed.
文摘By using the teleseismic receiver function method, this paper analyzes the crustal thickness and Vp/Vs ratios beneath the 4 National seismic stations （KMI, TNC, CD2 and PZH） in the Sichuan-Yunnan area. This study gives the variance of Moho depths and velocity ratios of the 4 stations in different directions. The results show that the Moho depth beneath the Kunming station is around 50km, and the vdocity ratio varies between 1.62 and 1.69. The thickness of crust and the velocity ratio do not change much with the direction. The crust beneath Tengchong station shows clear directivity, being 40.7km thick in the northeast and 49.7km thick in the southeast. The difference of the Vp/Vs values is remarkable between the two directions, reaching 0.2. The Chengdu station also has shallow Moho, about 40km, but is 8km deeper in the northeast and southwest and the vdocity ratio has a change of 0.13 between the two directions. The crust beneath the Panzhihua station is stable. In all directions, the Moho depth is around 60km and the Vp/Vs ratio doesn＇t change significantly.
基金sponsored by the Spark Program of Earthquake Technology of CEA in 2017(XH17026)Combination Project with Monitoring,Prediction and Scientific Research of Earthquake Technology,CEA(162205)
文摘In this paper,the long time series data of the well water-level data of 12 wells in the Sichuan and Yunnan area is analyzed by the Baytap-G tidal analysis software,and well water level tidal response characteristic parameters( amplitude ratio and phase change)are extracted. We analyzed the features of the shape and stage change,and characteristic parameters of the tidal response of well water level before and after the earthquakes,which can provide a new method and approach to analyzing the response relationships between well water level and earth tide and barometric pressure. The results show that Luguhu Well and 9 other wells are affected by earth tides,and their well water level amplitude ratios and phases are relatively stable; the Nanxi Well and Dayao Well water level changes are affected by the barometric pressure combined with tide force,and their well water level amplitude ratios and phases are more discrete. The water level amplitude ratios and phases of Jiangyou Well,Luguhu Well and Dongchuan Well are significant to large earthquakes,and the relationship between seismic energy density and water level amplitude ratios and phases of M_2 wave of the three wells are presented.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41472180 & 41172180)
文摘The Wenchuan earthquake occurred near the "triple junction" linking the Bayan Har block, the South China block, and the Sichuan-Yunnan rhombic block, and its influences on the surrounding blocks and the main fault zones in the Sichuan-Yunnan region, i.e., the block boundary zone, cannot be ignored. In this paper, changes of movement and stress of the fault zones before and after a strong earthquake were simulated based on the GPS repetition survey results recently obtained during 1999–2007, 2009–2011, and 2011–2013 with a two-dimensional finite-element contact model and the "block- loading" method. The results show that, before the Wenchuan earthquake, the movement of the Longmenshan fault zone was very slow and its compressive stress accumulated rapidly; after the Wenchuan earthquake, movements toward the E-SSE direction of the Bayan Har, southwestern Yunnan, and rhombic blocks were enhanced, and the dextral and horizontal compressive speeds and annual accumulative compressive stress of the Longmenshan fault zone increased markedly by factors of 4.5, 2.1, and 2.5, respectively. The southern Xianshuihe, Anninghe, Zemuhe, Daliangshan, and Lijiang-Xiaojinhe fault zones accumulated compressive stress rapidly, forming enhanced compressive stress zones along a NE strike crossing the central part of the Sichuan-Yunnan region. The tensional movement of the Xianshuihe fault zone was enhanced and the slip movement in the central part of the zone was reversed in a short time. The changes are tightly related to the medium-intensity earthquakes that occurred during the same period in this region, revealing that the spatial migration of seismic activity is related to changes of movement of the blocks.
