Ground motion simulation for the 21 May 2021 Ms 6.4 Yangbi, China, earthquake using stochastic finite-fault method

Abstract

On 21 May 2021, a 6.4-magnitude earthquake occurred in Yangbi County, Yunnan Province, China. To reproduce the ground motion characteristics of this earthquake, the stochastic finite-fault method was adopted. The ground motion records were analyzed to determine the source, path, and site parameters. Based on the optimization algorithm, the stress drop was set to 10 bar. The S-wave attenuation relation ( QS = 122.7 f0.44) was calculated by the spectral decay method. For the site effect, the site amplification was corrected using the horizontal-to-vertical spectral ratio method, and the zero-distance kappa filter had a value of 0.0328 s. To verify the reliability of the input parameters, the simulated 5%-damped pseudo-spectral acceleration, time history, and Chinese instrumental intensity were compared with those observed at six stations and finding acceptable consistency. Furthermore, the fitted model was used to simulate the ground motion of 2279 nodal points in the area, and the seismic intensity contours were obtained. Finally, the earthquake damage assessment was performed in the Yangbi County, and the difference between the designed spectral acceleration and that simulated at a specific period was regarded as the degree of earthquake damage. It was found that the reinforced concrete structures near the epicenter have sufficient safety reserves, and the earthquake damage was not serious. In summary, the stochastic finite-fault method with calibrated parameters could effectively synthesize the ground motion of specific sites, thus providing a basis for the earthquake damage assessment of engineering buildings.

Simulation of Ground Motion From Finite‐Fault Modeling Incorporating the Influence of Duration

“…The focal mechanism solution given by the Global Centroid Moment Tensor showed that the magnitude of the Yangbi mainshock was Mw 6.1, and it was a strike-slip earthquake. Studies have shown that the Yangbi earthquake occurred in an NW-SE right rotation strike-slip secondary fault on the west side of the Weixi-Qiaohou Fault in the north section of the Honghe Fault (Qiang et al, 2021). The Honghe Fault is the southwest boundary of the Sichuan-Yunnan rhombic block in the southeast of the Qinghai-Tibet Plateau.…”

“…The baseline correction and the cosine window are added at the beginning and end of the recording waveform to eliminate the recording error, and then the Butterworth non-causal band-pass filter (0.08-30 Hz) is applied to process the records. As one of the essential input parameters, and the effective frequency band of the recordings after filter process is 0.1-24 Hz (Qiang et al, 2021). The source model of the Yangbi earthquake was established using the scaling law based on global and local source parameters and truncated normal distribution density function (Dang, Cui, Liu, & Ji, 2023;Wang, 2004), as shown in Figure 2.…”

City-scale buildings damage estimation based on broadband physics-based ground motion simulation of 2021 Ms 6.4 Yangbi, China, earthquake

“…The 2021 M s 6.4 Yangbi earthquake with moment magnitude 6.1 occurred at the intersection of the Red River and Weixi-Qiaohou-Weishan faults, in a region of western Yunnan Province with complex mountain topography (see Figure 2). It is the largest earthquake occurred in this region in the past 45 years (Wang et al, 2023). Epicenter of this strike-slip earthquake is located at latitude 25.67°N, longitude 99.87°E.…”

Seismic Assessment of Typological Masonry Buildings Using Simulated Ground Motion Records: A Case Study for Azores, Portugal

“…However, they require accurate input-model parameters to produce a ground-shaking pattern that matches the specific characteristics of real regional records. Once these methods are calibrated with input-model parameters specific to a region of interest, they can serve as powerful tools for assessing the potential impact of future earthquake hazards and disasters [16].…”