[S-SS11] Strong Ground Motion and Earthquake Disaster

[SSS11-P15] Accessing maximum credible ground motions parameters using a multi-scheme method in the Kalawenguquan Fault, Xinjiang, China

*Jiangyi Li¹, Bengang Zhou¹ (1.Institute of Geology, China Earthquake Administration)

Keywords:maximum credible earthquake, stochastic finite-fault method, ground-motion simulation, multi-scheme simulation

The Tianshan Mountains are one of the most active seismic regions on the Chinese mainland, as testified by the occurrence of 15 earthquakes with magnitude larger than 7. The Kalawenguquan fault is known to be the northern edge of the Nalati fault and controls the northwestern edge of the Yultuz Basin (an internal block of the Tianshan Mountains). The results of high-resolution remote sensing image interpretation, geological field surveys, geomorphological surveys, drone aerial surveys, trench excavation, and the dating of trench samples with the radiocarbon-14 dating method provides fault parameters for ground-motion simulation. Based on the source model and a multi-scheme simulation, we used different modeling parameters to design a logic tree. We calculate all the combinations of each scheme using the stochastic finite-fault method to analyze the impact of different site locations on the simulation of near-field large earthquakes, and obtained the minimum, average, maximum, and 50th-, 84th-, and 95th-percentile PGA values and response spectrums. The results showed that the response spectra of the sites located on the hanging wall of the fault were higher than those of sites located on the footwall. Ground motion simulations wherein the site was located near the asperities were greater than when the site was located further away from the asperities. Further, when the site is located on a smaller asperity and has a certain distance from the largest asperity, the simulation results are greater. The results revealed that the source model established based on geological and geomorphological data has a great effect on the near-field ground motion simulation and can provide a reasonable evaluation for near-field strong ground motion simulations at major infrastructures.