Stochastic ground motion simulation of the 2016 Meinong, Taiwan earthquake

Abstract

We applied a stochastic method for the finite-fault modeling of strong ground motions to the 2016 Meinong, Taiwan earthquake. Newly developed attenuation models in Southern Taiwan with the frequency-dependent Q = 86.4f 0.73 and the high-frequency decay factor κ 0 were used in the synthetic model. The horizontal-to-vertical spectral ratios (HVSR) were calculated from weak motions and the Meinong mainshock and used for the site amplification correction of the synthetic waveforms produced by the stochastic ground motion simulation. Simulations incorporating the attenuation models and site correction improved the prediction of the S-wave envelope, duration, and peak ground acceleration (PGA). The nonlinear site response during the Meinong mainshock was identified by the degree of nonlinear site response (DNL), which is a summation of HVSR differences between weak motions and the Meinong mainshock as recorded by the Taiwan Strong Motion Instrument Program. The DNL showed a positive correlation with ground motion intensity. The surface site conditions influenced DNL strength. The percentage of PGA reduction calculated in this study can be an indicator of the spatial distribution of the degree of nonlinear soil effects on the Meinong earthquake in the time domain. Areas that had high levels of PGA reduction overlap with areas that had high liquefaction potential. Based on the residual analysis, forward directivity was identified in a 105° range in the northwestward direction. The amplification of forward rupture directivity was three times greater than the backward rupture directivity. which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Source and strong-motion characteristics of two M > 6 buried earthquakes in southwest Taiwan

“…Chen et al (2019) obtained a strong-motion generation area (SMGA) model of the 2016 Meinong event on the NS-striking fault plane. However, most relevant studies (e.g., Huang et al 2016;Lee et al 2016;Chen et al 2017;Kanamori et al 2017;Diao et al 2018a, b;Lin et al 2018;Chen, 2019) have suggested an EW-striking rupture. We also considered the EW-striking fault plane for the 2016 Meinong event.…”

“…Moreover, it could be noticed that the liquefactions also occurred within the high PGV region for both the 2010 Jiashian and 2016 Meinong events. Boore et al (1989) indicated that PGA could be reduced through deamplification by the nonlinear soil effect, and Chen et al (2017) demonstrated that the liquefactions caused by the 2016 Meinong event were located in a region with a significant reduction in PGA. Several studies have suggested that the relatively low-velocity region is beneath the significant coseismic uplift region of the 2016 Meinong event, which could be controlled by the high pore fluid pressure within (See figure on next page.)…”

“…2, stations CHY089 and KAU012 both displayed a significantly low spectral ratio in the high-frequency band, which might be related to deamplification due to the nonlinear site effect (Beresnev and Wen 1996;Boore et al 1989). Chen et al (2017) calculated the degree of nonlinearity (DNL) for the 2016 Meinong event, with the frequency range of 0.5-20 Hz. The rupture-forward stations CHY063, CHY089, and CHY070 represent the relative low, medium, and maximum DNL with values of 3.58, 5.29, and 10.71 (red lines in Fig.…”

“…6) and could be the factor causing the underestimation of synthetic waveforms for low-frequency content at these three stations. Following Chen et al (2017), we calculated the DNL at some stations for the 2010 Jiashian event (blue lines in Fig. 8), which was roughly low with values between 3.2 and 4.6.…”

Special issue “Effect of surface geology on seismic motion: challenges of applying ground motion simulation to seismology and earthquake engineering”

“…Ren et al (2017) quantify the amount of soil nonlinearity by using various indices based on the horizontal-to-vertical spectral ratio applied to strong ground motion records obtained during and after the 2008 Wenchuan earthquake, China (Ms8.0), and investigate their correlation with loading or site parameters. Similarly, Chen et al (2017) analyze the amount of nonlinear site response in the (estimated) strong shaking area in relation to the loading and site parameters for the 2016 Meinong earthquake and propose a method to incorporate the resulting nonlinear frequency shifts in otherwise linear stochastic ground motion simulations. Lu et al (2017) investigate the degree of damage to low-rise buildings as a result of soil liquefaction in the superficial layer during the 2016 Meinong earthquake, Taiwan, and emphasize some nonconservative limitations of existing methods, linked to poor accounting of the underlying site conditions.…”