ALBERT

Description: 〈span〉〈div〉Abstract〈/div〉Based on the 72 free‐field accelerograms with the closest site‐to‐rupture distances (Rrup) less than 300 km in the 2013 moment magnitude (Mw) 6.7 Lushan earthquake, this work calculates the four simplified frequency‐content parameters (the mean period [Tm], the predominant spectral period [Tp], the average spectral period [Tavg], and the smoothed spectral predominant period [To]) and compares the calculation results with empirical models. For the Lushan earthquake, the spatial contours of the recorded frequency‐content parameters show that the long‐period (〉1  s) region is observed in the southwest of the study area, with Rrup〉200  km. The long‐period region is mainly caused by the Quaternary basins that are distributed along‐strike directions of many large faults. When predicting the frequency content of ground motions for the Lushan event, the models of Lee (L09) and Rathje 〈span〉et al.〈/span〉 (RFRB04) for T0 exhibit the best‐predictive efficiency. For the parameter Tm, the quantitative assessment of all models indicates that the Du (DU17) model is the most efficient. The comparison between the recorded frequency‐content parameters of the Lushan event and empirical models shows that the frequency content of strong motions is region dependent. All models’ intraevent residuals for the four parameters are less for Rrup≤100  km than for Rrup〉100  km. The maximum positive intraevent residual for To is near or in the long‐period region, which indicates the effect of geology structure on the recorded frequency‐content parameters of strong motions.〈/span〉

Description: 〈span〉〈div〉Abstract〈/div〉Based on the 72 free‐field accelerograms with the closest site‐to‐rupture distances (Rrup) less than 300 km in the 2013 moment magnitude (Mw) 6.7 Lushan earthquake, this work calculates the four simplified frequency‐content parameters (the mean period [Tm], the predominant spectral period [Tp], the average spectral period [Tavg], and the smoothed spectral predominant period [To]) and compares the calculation results with empirical models. For the Lushan earthquake, the spatial contours of the recorded frequency‐content parameters show that the long‐period (〉1  s) region is observed in the southwest of the study area, with Rrup〉200  km. The long‐period region is mainly caused by the Quaternary basins that are distributed along‐strike directions of many large faults. When predicting the frequency content of ground motions for the Lushan event, the models of Lee (L09) and Rathje 〈span〉et al.〈/span〉 (RFRB04) for T0 exhibit the best‐predictive efficiency. For the parameter Tm, the quantitative assessment of all models indicates that the Du (DU17) model is the most efficient. The comparison between the recorded frequency‐content parameters of the Lushan event and empirical models shows that the frequency content of strong motions is region dependent. All models’ intraevent residuals for the four parameters are less for Rrup≤100  km than for Rrup〉100  km. The maximum positive intraevent residual for To is near or in the long‐period region, which indicates the effect of geology structure on the recorded frequency‐content parameters of strong motions.〈/span〉

Description: 〈span〉〈div〉Abstract〈/div〉Using 72 free‐field accelerograms with the closest site‐rupture distances (Rrup) less than 300 km, this study calculates the recorded significant duration of the 2013 Mw 6.7 Lushan earthquake and compares the calculated results with empirical model predictions. The significant duration parameters are for 5%–75% (D5–75) and 5%–95% (D5–95) of the normalized Arias intensity. For Rrup〈150  km, the models of 〈a href="https://pubs.geoscienceworld.org/bssa#rf18"〉Du and Wang (2017〈/a〉; hereafter, DW17) are relatively less biased in predicting the Lushan significant duration. The goodness‐of‐fit results indicate that the models of DW17, 〈a href="https://pubs.geoscienceworld.org/bssa#rf2"〉Afshari and Stewart (2016〈/a〉; hereafter, AS16), and 〈a href="https://pubs.geoscienceworld.org/bssa#rf25"〉Kempton and Stewart (2006〈/a〉; hereafter, KS06) are the best models to predict D5–75 of the Lushan event. Meanwhile, most of the selected empirical models predict the Lushan event better for D5–75 than for D5–95. Moreover, the enrichment of high‐frequency components of ground motion causes the recorded D5–95 of the Lushan event to be larger than median predictions in high‐frequency bands. Among the five selected earthquakes (1994 Mw 6.7 Northridge, 2003 Mw 6.5 San Simeon, 2004 Mw 6.6 Niigata, 2008 Mw 7.9 Wenchuan, and 2013 Mw 6.7 Lushan earthquakes), the Lushan earthquake is predicted relatively better by all empirical models. The intraevent and interevent residuals of AS16 model from China earthquakes are within the scatter of those from the events in the Next Generation Attenuation‐West2 (NGA‐West2) database, indicating that the China earthquake significant duration is consistent with the model developed through the NGA‐West2 database. Furthermore, the regional dependences of significant duration are not observed for the Wenchuan or the Lushan earthquake.〈/span〉

Description: 〈span〉〈div〉Abstract〈/div〉Using 72 free‐field accelerograms with the closest site‐rupture distances (Rrup) less than 300 km, this study calculates the recorded significant duration of the 2013 Mw 6.7 Lushan earthquake and compares the calculated results with empirical model predictions. The significant duration parameters are for 5%–75% (D5–75) and 5%–95% (D5–95) of the normalized Arias intensity. For Rrup〈150  km, the models of 〈a href="https://pubs.geoscienceworld.org/bssa#rf18"〉Du and Wang (2017〈/a〉; hereafter, DW17) are relatively less biased in predicting the Lushan significant duration. The goodness‐of‐fit results indicate that the models of DW17, 〈a href="https://pubs.geoscienceworld.org/bssa#rf2"〉Afshari and Stewart (2016〈/a〉; hereafter, AS16), and 〈a href="https://pubs.geoscienceworld.org/bssa#rf25"〉Kempton and Stewart (2006〈/a〉; hereafter, KS06) are the best models to predict D5–75 of the Lushan event. Meanwhile, most of the selected empirical models predict the Lushan event better for D5–75 than for D5–95. Moreover, the enrichment of high‐frequency components of ground motion causes the recorded D5–95 of the Lushan event to be larger than median predictions in high‐frequency bands. Among the five selected earthquakes (1994 Mw 6.7 Northridge, 2003 Mw 6.5 San Simeon, 2004 Mw 6.6 Niigata, 2008 Mw 7.9 Wenchuan, and 2013 Mw 6.7 Lushan earthquakes), the Lushan earthquake is predicted relatively better by all empirical models. The intraevent and interevent residuals of AS16 model from China earthquakes are within the scatter of those from the events in the Next Generation Attenuation‐West2 (NGA‐West2) database, indicating that the China earthquake significant duration is consistent with the model developed through the NGA‐West2 database. Furthermore, the regional dependences of significant duration are not observed for the Wenchuan or the Lushan earthquake.〈/span〉