Dynamic corner frequency in source spectral model for stochastic synthesis of ground motion

Abstract

The static corner frequency and dynamic corner frequency in stochastic synthesis of ground motion from finite-fault modeling are introduced, and conceptual disadvantages of the two are discussed in this paper. Furthermore, the non-uniform radiation of seismic wave on the fault plane, as well as the trend of the larger rupture area, the lower corner frequency, can be described by the source spectral model developed by the authors. A new dynamic corner frequency can be developed directly from the model. The dependence of ground motion on the size of subfault can be eliminated if this source spectral model is adopted in the synthesis. Finally, the approach presented is validated from the comparison between the synthesized and observed ground motions at six rock stations during the Northridge earthquake in 1994.

Comparison of the Dynamic and Static Corner Frequencies in Ground Motion Simulation: Cases Study of Jiuzhaigou Earthquake and Northridge Earthquake

“…In contrast, the backward effect takes place at the time of propagation of rupture from a site that produces low amplitudes and long duration motions in the long term (Sun, 2010). The ORR station had undervalued response spectra nearly during the whole period, which conformed to the results obtained by Beresnev and Atkinson (1998b) and Sun et al (2009). The reasons for these differences may be attributed to the fact that the selected site amplification factor fail to describe the local geological conditions, which may require complete site data for analysis.…”

“…In addition, the results of the two models are similar. In the case of a few stations, the simulated results of the two models are significantly different from the observed results, which is found to be consistent with the results obtained by Sun et al (2009) and Beresnev and Atkinson (1998b). These differences may be caused by local site effects, topography, and basin geometry effects, which may require complete site data for analysis.…”

“…Although the corner frequency gradually decreases when the rupture process expands, the corner frequency of the subfault when the former rupture is always higher than that of the latter, and the corner frequency of the subfault where the rupture starting point is located is the largest. Sun et al (2009), Wang et al (2015), and other scholars have attempted to improve the source spectrum, but have never been able to ignore the influence of subfault size on the far-field received energy.…”

“…During the propagation of the rupture to each subfault onto the major fault, the subfault corner frequency reaches the lower limit. This is called the static corner frequency for the entire fault and is the underestimated corner frequency (Sun et al, 2009;Wang et al, 2015). Consequently, the high-frequency received energy and the level spectrum are significantly underestimated.…”

Stochastic Simulation of Ground Motions of the Wenchuan Earthquake Using Slip-Based Corner Frequency and Scaling Factor

“…The stochastic finite-fault modeling technique has been developed to simulate ground motions near the epicenter of a large earthquake [1][2][3][4][5][6][7]. In the modeling, the fault is divided into many subfaults, and the ground motion from the entire fault is obtained by summing the contributions from all subfaults with time lags.…”