Numerical Simulation of Stress Evolution and Earthquake Sequence of the Sichuan-Yunnan Region, China

Date: 4/24/2019

Time: 06:00 PM

Room: Grand Ballroom

The Sichuan-Yunnan region is located in the southern section of the South-North seismic belt in China, behaves as lots of left-lateral strike –slip active fault system. Since 1900 , more than 30 earthquakes of M > 6.5 occurred sequentially in this region. How did the stresses evolve during the last more than 100 years, how did the earthquakes interact with each other? Can this knowledge help us to forecast the future seismic hazards? In this essay, we tried to simulate the evolution of the stress field and the earthquake sequence in the Sichuan-Yunnan region of China within the last 110 years with a 2-D finite element model.

In this study, we estimated a reasonable range of initial stress, and then based on Coulomb-Mohr criterion to regenerate the earthquake sequence, starting from the Daofu earthquake of 1904. We regenerated all of the 30 historical earthquakes, considering both the tectonic loading and interaction between the earthquakes. Ultimately we got a sketch of the present stress. Of course, a single model with certain initial stress is just one possible model. Consequently the potential seismic hazards distribution based on a single model is not convincing. We made test on tens of thousands of possible initial stress, all of them can produce the historical earthquakes occurred sequentially, and summarized all kinds of calculated probabilities of the future seismic activity. Although we cannot provide the exact state in the future, but we can narrow the estimate of regions where is in high probability of risk. Our primary results indicate that the Xianshuihe fault and adjacent area is one of such zones with higher risk than other regions in the future. We emphasized the importance of the initial stress field for the earthquake sequence, and provided a probabilistic assessment for future seismic hazards. This study may bring some new insights to estimate the initial stress, earthquake triggering, and the stress field evolution.

Presenting Author: Peiyu Dong

Authors