Using GPS observations of horizontal movement from 2001 to 2003 and the cross-fault mobile short-levelling data of 1988～2003, and with the aid of the improved negative dislocation model and the time-varying curve of ...Using GPS observations of horizontal movement from 2001 to 2003 and the cross-fault mobile short-levelling data of 1988～2003, and with the aid of the improved negative dislocation model and the time-varying curve of strain intensity ratio of fault deformation, the regional tectonic deformation background and medium- and short-term precursors related to the preparation of the Minle-Shandan earthquakes of M S6.1 and M S5.8 on October 25, 2003 are investigated. The results reveal that, under the background of the wide-range deformation adjustment, short-term relaxation and recovery caused by the Kunlun Mountains earthquake of M S8.1, the hypocenters of the earthquakes are located on the north edge of the shear stress enhancement zone between the compressional locked segments of block boundary fault, a place which may represent an accelerated strain accumulation. An obvious anomaly of strain intensity ratio appeared in short-levelling measurements crossing over the fault at the Shihuiyaokou site, the closest to the epicenters, 3 months before the occurrence of the earthquakes. In addition, the variation in number of anomalies from 10-odd days to months before the earthquakes in the entire monitoring area and the anomaly concentration and local enhancement relative to near source in the 3 months before the earthquakes are regarded to be precursors to the two events.展开更多
Based on basic data used in compiling the Zonation Map of Earthquake Ground Motion Parameters in China, recent research on seismic safety assessment for engineering sites in central-southern Hunan Province, the new at...Based on basic data used in compiling the Zonation Map of Earthquake Ground Motion Parameters in China, recent research on seismic safety assessment for engineering sites in central-southern Hunan Province, the new attenuation relationships of moderate earthquakes and the background seismicity data obtained by modern instrumental earthquake records since 1970, a new result of seismic zonation of central-southern Hunan Province is provided. The result shows that the area with PGA=0.05g has obviously increased in the new map compared with the previous one and is relatively consistent with the seismic disaster characteristics of moderate earthquakes that took place in the central-southern part of Hunan in recent years. This result will benefit the research and compilation of a new-generation seismic zonation map of earthquake ground motion parameters and the seismic hazard assessment in the moderate earthquake active regions in the central and eastern part of China.展开更多
文摘Using GPS observations of horizontal movement from 2001 to 2003 and the cross-fault mobile short-levelling data of 1988～2003, and with the aid of the improved negative dislocation model and the time-varying curve of strain intensity ratio of fault deformation, the regional tectonic deformation background and medium- and short-term precursors related to the preparation of the Minle-Shandan earthquakes of M S6.1 and M S5.8 on October 25, 2003 are investigated. The results reveal that, under the background of the wide-range deformation adjustment, short-term relaxation and recovery caused by the Kunlun Mountains earthquake of M S8.1, the hypocenters of the earthquakes are located on the north edge of the shear stress enhancement zone between the compressional locked segments of block boundary fault, a place which may represent an accelerated strain accumulation. An obvious anomaly of strain intensity ratio appeared in short-levelling measurements crossing over the fault at the Shihuiyaokou site, the closest to the epicenters, 3 months before the occurrence of the earthquakes. In addition, the variation in number of anomalies from 10-odd days to months before the earthquakes in the entire monitoring area and the anomaly concentration and local enhancement relative to near source in the 3 months before the earthquakes are regarded to be precursors to the two events.
基金This research was sponsored under the project entitled"Research on key techniques for strong earthquake risk zonation"(2006BAC13B01) of the sciencetechnology support program of Ministry of Science and Technology of China
文摘Based on basic data used in compiling the Zonation Map of Earthquake Ground Motion Parameters in China, recent research on seismic safety assessment for engineering sites in central-southern Hunan Province, the new attenuation relationships of moderate earthquakes and the background seismicity data obtained by modern instrumental earthquake records since 1970, a new result of seismic zonation of central-southern Hunan Province is provided. The result shows that the area with PGA=0.05g has obviously increased in the new map compared with the previous one and is relatively consistent with the seismic disaster characteristics of moderate earthquakes that took place in the central-southern part of Hunan in recent years. This result will benefit the research and compilation of a new-generation seismic zonation map of earthquake ground motion parameters and the seismic hazard assessment in the moderate earthquake active regions in the central and eastern part of China.
