We employ a three-dimensional finite element model to study the relationship between the tectonic stress-strain fields and seismic activities in Yunnan area, basing on the updated GPS-derived displacement as the boundary constraints. Through comparing the stress-strain fields, strain energy density with the Ms≥6 earthquakes distribution in recent one hundred years. We found that the strong earthquake distribution corresponds well with the stress high value or transitional sections, also the upper strain energy density regions, especially the magnitude above seven.
Earthquakes result from elastic stress built up in part by tectonic motion. GPS-derived crust strain measurements provide an opportunity to model the relative growth of crust stress in detail. The observed strain field is not uniform, thus it is expected that the distribution of crustal stress will also irregular. In this paper, the stress-strain field in Yunnan area is calculated with a three-dimensional finite element model that is loaded by the updated observed GPS displacements. The Yunnan area was located at the south-eastern margin of Qing-Tibet Plateau, and also the intense distortion belt deduced from the collision of India plate toward the Eurasian plate. In recent thirty years, it experienced two stages of strong earthquake activities, during this periods, there happens Tonghai Ms7.7, Daguan Ms 7.1, Longling Ms7.3, Lanchang Ms7.4, Menglian Ms7.3 and Lijiang Ms7.0 earthquakes, as well as many Ms6.0 earthquakes occurred (Tang, 1989). Therefore, a great number of highly effective observations and researches of seismology, active structure and crustal deformation have been carried out in this area (Wang J C, 1991; Yang G Y, 1981, 1982; Naoyuki Kato, 1999; Stewart W. Smith, 1969; Jiao M R, 1999; Liu C Q, 1998). At this, we choose this area as the target to study the stress-strain fields and theirs relationship with the happened strong earthquakes.