ShiGuo LI, JunJu XIE, ChangLong LI, KeWei LI. 2025: Impact of Local Site Conditions on Seismic Hazard inthe Xinjiang Region. Acta Seismologica Sinica. DOI: 10.11939/jass.20250023
Citation: ShiGuo LI, JunJu XIE, ChangLong LI, KeWei LI. 2025: Impact of Local Site Conditions on Seismic Hazard inthe Xinjiang Region. Acta Seismologica Sinica. DOI: 10.11939/jass.20250023

Impact of Local Site Conditions on Seismic Hazard inthe Xinjiang Region

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  • Received Date: February 24, 2025
  • Revised Date: April 14, 2025
  • Accepted Date: April 14, 2025
  • Available Online: June 10, 2025
  • The Xinjiang region is characterized by frequent seismic activity and complex geological conditions, where local site conditions significantly influence strong ground motions and engineering seismic damage. This study investigates the impact of site overlying soil layers on regional seismic hazard in Xinjiang, based on regional shear-wave velocity distribution and site classification data. Using the potential seismic source zoning method from the fifth-generation seismic zonation map of China and the regional ground motion attenuation model proposed by Bindi et al., seismic hazard results—including peak ground acceleration (PGA) and spectral accelerations (Sa) at periods of 0.2 s, 0.5 s, and 1.0 s—were calculated for bedrock Site Class I1 (VS30 = 742 m/s) and actual sites under 50-year exceedance probabilities of 63%, 10%, and 2%. The differences in seismic hazard between Site Class II/III and Site Class I1 in Xinjiang were analyzed across varying exceedance probabilities. Adjustment coefficients for ground motion parameters at different probability levels were statistically derived for soil sites. The results indicate that influenced by site overlying soil layers, the PGA and response spectral accelerations at 0.2 s, 0.5 s, and 1.0 s exhibit significant amplification in soft soil regions such as the Tarim and Junggar Basins, while ground motion parameters at the same probability level are notably reduced in hard-rock areas like the Altai, Tianshan, and Kunlun Mountains. For Site Class II and III, the adjustment factors for response spectral accelerations vary significantly across different periods, showing a pattern of first increasing and then decreasing with increasing period. The adjustment factors reach their maximum at a period of 0.4 s, highlighting the substantial differences in site effects across spectral periods. For different exceedance probability levels, the adjustment factors for Site Class II and III are nearly identical, suggesting minimal influence of regional seismic hazard levels on site-specific adjustments. Compared to the average adjustment factors in the fifth-generation seismic zonation map, the adjustment factors for Site Class I1 in Xinjiang are smaller, while those for Site Class III are larger. This study provides valuable insights for seismic fortification by considering the impact of regional site conditions.
     
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