摘要
Spatial scanning is done for two regions in Chinese Mainland,where displayed a denseprecursory network during 1994～1998.The two regions are the mid-southern segment of theNorth-south seismic belt(20°～35°N,95°～110°E)and North China(36°～42°N,110°～120°E).We took 0.5°×0.5°as a spatial window with a step of 0.25°and 4 months as atemporal window with a step of 1 month.For the two regions,the anomaly density is scannedfrom 1994 and 1995 respectively in the two regions.The precursory anomalies are all fromthe Division of Seismic Trend in China and the Division of Seismic Trend in the Capital Area,Center for Analysis and Prediction,China Seismological Bureau.A seismogenic tectonicmodel is introduced to explain the scanning results.In the model,the frictional strength ofthe focal sources is distributed randomly.After the boundary plate motion rate and all othergeological parameters are given,the stress of the sources in the system changesinhomogenously due to the variation of the frictional
Spatial scanning is done for two regions in Chinese Mainland, where displayed a dense precursory network during 1994-1998. The two regions are the mid-southern segment of the North-south seismic belt (20°-35°N, 95°~110°E) and North China (36°-42°N, 110°-120°E). We took 0. 5°× 0. 5° as a spatial window with a step of 0.25°and 4 months as a temporal window with a step of 1 month. For the two regions, the anomaly density is scanned from 1994 and 1995 respectively in the two regions. The precursory anomalies are all from the Division of Seismic Trend in China and the Division of Seismic Trend in the Capital Area, Center for Analysis and Prediction, China Seismological Bureau. A seismogenic tectonic model is introduced to explain the scanning results. In the model, the frictional strength of the focal sources is distributed randomly. After the boundary plate motion rate and all other geological parameters are given, the stress of the sources in the system changes inhomogenously due to the variation of the frictional strength. The model can provide a series of earthquakes when the stress of some sources is higher than the static strength based on Colnmb friction law. The stress can be transferred among the sources within the system due to the special coupling structure of the model, which also makes the stress field change intricately and keep the relation among strong quakes complex. For most of the sources, the rupture of the source is caused by high stress, while some sources broken under a relative low stress level, which provides a good explanation for the gained scanning results.
基金
This project was sponsored by the China Seismological Bureau(95-04-03-03-02)
