[S-SS10] Strong Ground Motion and Earthquake Disaster

[SSS10-13] High-Probability Broadband Waveform Synthesis of the Lushan Earthquake Considering Source Uncertainty and Small Earthquake Diversity

*Zongchao Li¹, Zhiwei Ji², Hiroe Miyake³, Jize Sun⁴, Mengtan Gao¹, Yi Ding⁵, Quanbo Luo⁶ (1.Institute of Geophysics, China Earthquake Administration, 2.Institute of Earthquake Forecasting, China Earthquake Administration, 3.Earthquake Research Institute, The University of Tokyo, 4.Shenzhen Academy of Disaster Prevention and Reduction, 5.Beijing University of Technology, 6.Southwest University of Science and Technology)

Keywords:Green’s function database, source parameter uncertainty, reasonable range, high probability ground motion, broadband frequency

With the continuous improvement of comprehensive earthquake monitoring capabilities in the past few decades, China has accumulated much seismic data, especially for earthquakes below M_s 5.0. These small earthquake records should have great value in the application of strong motion seismology, such as synthesizing large earthquakes. In this study, we propose an approach to synthesizing high-probability ground motions of broadband rupture scenarios or historical earthquakes by using data from diverse small earthquakes. To obtain more refined broadband ground motion, we consider multiple uncertainty characteristics of the source parameters and simplify the combination scenarios of source models through sensitivity analysis schemes. We also verified the reliability and rationality of the seismic motion estimation results from indirect perspectives. This study verified that earthquakes of M_s 4.0-M_s 4.9 with arbitrary focal mechanisms can be used as Green’s function to synthesize the strong motion of large earthquakes at the same station with the same propagation path and site environment. We found that the PGA and PGV statistical results of all earthquake scenarios at each station are preliminarily in line with the Gaussian distribution or Chi-Square (χ²) distribution. It can also offer ground motion inputs more representative of the local area, which can be valuable for designing seismic-resistant buildings.