2:15 PM - 2:30 PM
[S07-5-04] 3D numerical modeling of seismic wave propagation and amplification in Qaidam basin
Qaidam basin is the largest basin within Qinghai-Tibetan plateau with area of ~120,000 km2. Maximum thickness of basin sediments is about 12 km. Seismograms recorded by International Deep Profiling of Tibet and the Himalaya Phase IV (INDEPTH IV) seismic stations during 2008 show clear spatial variations and seismic ground motion amplification was observed in several events.
In this study, we constructed a three-dimension seismic wave velocity model of Qaidam basin based on previous studies, including three sedimentary layers from Paleogene to Quaternary and perform 3D numerical modeling of seismic wave propagation in Qaidam basin with 3D Finite-difference method (FDM). We employ a high-performance parallel supercomputer to simulate seismic wave propagation in the area around the large Qaidam basin. Based on modeling, we will explain the mechanism of the development of observed long-period surface wave in the data and dramatic amplification of ground motion in the Qaidam basin.
Three different models, 1) model only contains crust with flat surface, 2) crust model with topography, 3) model contains sedimentary layers and topography over crust, were simulated to evaluate the effects on seismograms in basin. Based on simulation, slightly amplification from 0.4 -1.0 Hz caused by topography in vertical component of stations installed in mountain area (higher altitude) around basin. Considerably amplification by sedimentary layer from 0.1 - 0.8 Hz in three components of stations in the middle of basin. 2008 Da-Qaidam Mw6.3 earthquake together with two aftershocks and 2001 Kunlunshan Mw7.8 earthquake around Qaidam basin were simulated to estimate amplification effects of basin on earthquake with different magnitude and with different azimuth.
In this study, we constructed a three-dimension seismic wave velocity model of Qaidam basin based on previous studies, including three sedimentary layers from Paleogene to Quaternary and perform 3D numerical modeling of seismic wave propagation in Qaidam basin with 3D Finite-difference method (FDM). We employ a high-performance parallel supercomputer to simulate seismic wave propagation in the area around the large Qaidam basin. Based on modeling, we will explain the mechanism of the development of observed long-period surface wave in the data and dramatic amplification of ground motion in the Qaidam basin.
Three different models, 1) model only contains crust with flat surface, 2) crust model with topography, 3) model contains sedimentary layers and topography over crust, were simulated to evaluate the effects on seismograms in basin. Based on simulation, slightly amplification from 0.4 -1.0 Hz caused by topography in vertical component of stations installed in mountain area (higher altitude) around basin. Considerably amplification by sedimentary layer from 0.1 - 0.8 Hz in three components of stations in the middle of basin. 2008 Da-Qaidam Mw6.3 earthquake together with two aftershocks and 2001 Kunlunshan Mw7.8 earthquake around Qaidam basin were simulated to estimate amplification effects of basin on earthquake with different magnitude and with different azimuth.