AN EXPERIMENTAL STUDY ON THE CURRENT TECTONIC STRESS FIELD AND SEISMICITY OF SOUTHWESTERN CHINA
Model Experiment Group, Institute of Geology, Aeademia Sinica
Basing on plenty of field data and simulation experiments this paper deals preliminarily with the current tectonic stress field, seismicity and the generation of earthquakes in the Yunnan-West Sichuan region by means of stress analysis.The experiments show that the rotationo-shearing collision of the Indian Plate against the Eurasian Plate is" the main cause of the current tectonic stress field of the region under study. The action of the Indian Plate is expressed in the following two ways: the one is the NB running compressive stress which gradually decreases from the north towards the south; the other is the SBE-ward movement of the "rhombic faulted block" formed by the Xianshuihe Fault, the Honghe Fault and the Anning Fault.From the experiments one may note that the relative movement between the "faulted blocks" exerts its influence on the stress field. The movement pattern of various faulted blocks leads to various modes of stress accumulation as well as various types of regularity of seismicity. Consequently the regularity of the earthquake migrations for this region may be fairly well explained.