The seismic response characteristics of the Yellow River terrace are crucial, as it is one of the key human activity areas. Seismic response characteristics of Yellow River terrace stations in Ningxia were analyzed using strong-motion earthquake records from seismic observations in the Loess Plateau and corresponding station data, employing the Horizontal-to-Vertical Velocity Response Spectrum Ratio method. The seismic vulnerability coefficient (Kg) was computed, and the bedrock depth was estimated. The results indicate that the spectral ratio curves of the Yellow River terrace can be classified into three types: single-peak, multi-peak, and ambiguous-peak types. The predominant period of the terraces ranges from 0.12 to 1.22 s, and the amplification factor ranges from 2.87 to 10.29. The calculated Kg values range from 2.09 to 63.24, and the bedrock depth ranges from 10.68 to 168.11 m. The site's predominant period, amplification factor, high Kg values, and deep bedrock depths can significantly impact seismic design, potentially leading to greater damage during earthquakes. Based on the predominant period, Kg values, and bedrock depth, the seismic vulnerability of Yinchuan is assessed to be high.

There are only a few worldwide cases where distant earthquakes have caused damage. One such example is the municipality of Centro located in Tabasco, Southeast Mexico, approximately 360 km from the Mesoamerican trench, where a strong ground shaking was felt during the M(w)8.2 earthquake of September 08, 2017. In this study, for 20 sites shear-wave velocity profiles were determined using Multichannel Analysis of Surface Wave and V-P profiles using Seismic Refraction techniques. Also V-S30 (shear-wave velocity up to a depth of 30 m) values were obtained for the same sites. The distribution of the V-S30 values in the study area varied from 120 m/s to 570 m/s and it was observed that sites where damage to buildings were reported lie near areas with V-S30 < 270 m/s. Additionally, the transfer functions of the 20 sites were estimated using the Thomson-Haskell method. The fundamental frequencies (f(0)) obtained through transfer functions had values varying from 0.9 <= f(0) <= 2.0 Hz. These transfer functions were convolved with the signal that represents the record in the bottom of the soil column in the study area to obtain synthetic accelerograms in the municipality of Centro. The only accelerograph station located in the study area (VHSA station) was used as a reference site. The horizontal-to-vertical spectral ratio of the VHSA location was used for site characterization to assess the effects of regional events. The study concludes that several factors contribute to the susceptibility of Centro municipality to distant seismic events. These factors include low shear-wave velocity (V-s), low fundamental frequency (f(0)), local site conditions, the presence of buildings on former lake zones, low seismic wave attenuation, and the regions' overall vulnerability to regional earthquakes.

Bhaktapur, lying in the Kathmandu Basin, suffered damages during the 2015 Gorkha Earthquake, potentially exacerbated by local site effects. This research addresses the lack of site response study on Suryabinayak Municipality, located in the southern part of Bhaktapur district. Horizontal to Vertical Spectral Ratio (HVSR) and Floor Spectral Ratio (FSR) methods were employed to determine the fundamental frequencies of soil deposits at 241 free field stations and 20 Reinforced Concrete (RC) isolated buildings respectively. The fundamental frequency of soil deposits varies from 0.27 Hz to 10.00 Hz. Higher frequencies were noted near the basin edges, attributed to shallow sediment deposits, whereas a lower frequencies prevailed towards the basin centre due to an increase in sediment thickness. Out of 20 buildings studied, 7 are highly susceptible to soil-structure resonance as the frequency disparity between building and free-field is less than 15%. This research not only quantified the frequency distribution and soil-structure resonance likelihood but also established a correlation between building height and its fundamental frequency. A significant correlation is observed with a coefficient of determination (R2) value of 60.64% and 83.36% in the longitudinal and transverse directions respectively. The study's results can be endorsed to mitigate seismic hazards, build seismic-resilient structures, and maintain historical monuments.

Microtremor tests and finite element numerical simulations were used to analyze the seismic ground motion effects of the Yunnan Dayao sedimentary basin. The results of the microtremor relative to the reference point spectral ratio (H-S/H-R) method showed that the spectral ratio curves of each observation point in Dayao basin show multipeak characteristics, indicating that the site consists of different soil layers; the predominant frequencies of each observation point mainly are 6 similar to 9 Hz in the basin and there are lots of differences in the predominant frequencies of different observation points, which indicate that the site stiffness of each observation point is different; the differences of spectral ratios between the east-west directions (EW) and the north-south directions (NS) reveal the site's anisotropy. The amplification coefficient characteristics of each observation point in the basin obtained by numerical simulation show that the predominant frequency is 6 similar to 9 Hz; the amplification coefficients of each observation point are different; the edge effect and the focusing effect amplify the seismic ground motion in the basin; the different amplification coefficients of the two sub-basins reflect the significant effect of the basin soil layers' differences on the seismic ground motion, the site is softer and amplification coefficients are larger; the slope degree of basin edges significantly affects the seismic ground motion near the basins edge, the amplification coefficients of the slope steeper and amplification coefficients larger. This study demonstrates that the microtremor test spectral ratio (H-S/H-R) method has good reliability applied to the analysis of basin effect and combining the finite element numerical simulation method is more effective in revealing the basin effect mechanism.

The emphasis of seismic design regulations on applying nonlinear dynamic analyses (NDAs) promotes using accelerograms that characterize site-specific ground motions. Commonly, amplitude levels of such accelerograms are defined by a target spectrum that could be based on a uniform hazard spectrum (UHS), which is determined by a probabilistic seismic hazard analysis (PSHA) and represents a response spectrum with ordinates having an equal probability of being exceeded within a given return period, Tr\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${T}_{r}$$\end{document}. Conversely, the definition of ground-motion duration levels is not yet properly defined in current regulations to select accelerograms. Thus, adhering to data handling as that for amplitude ground-motion parameters, this study motivates executing PSHAs to define hazard-consistent levels for the ground-motion duration. That is, accelerograms can be selected to match both amplitude and duration ground-motion levels associated with Tr\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${T}_{r}$$\end{document}. Further, fragility functions conditional on Tr\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${T}_{r}$$\end{document} that cover typical performance objectives can be developed using sets of hazard-consistent accelerograms to implement, e.g., multiple stripe analyses (MSAs). To demonstrate the importance of choosing fully hazard-consistent accelerograms to perform NDAs, this study includes the displacement- and energy-based seismic-response evaluation of a steel frame building located at different soil-profile sites in Mexico City. Sets of fully hazard-consistent accelerograms and solely amplitude-based hazard-consistent accelerograms were artificially generated per site for values of Tr\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${T}_{r}$$\end{document} up to 5000 years. Results indicate that the probability of failure can be underestimated if the ground-motion duration is unvaried in MSAs, e.g., structural damage caused by 50-year return-period or higher events can be more noticeable when fully hazard-consistent accelerograms take place.

The single-station microtremor method is one of the fastest, most reliable, and cheapest methods used to identify dynamic soil properties. This study utilizes 49 single-station microtremor measurements to identify the dynamic soil properties of the Hilalkent quarter of the Yakutiye district in Erzurum. Soil dominant frequency and the amplification factor were calculated by using the Nakamura horizontal/vertical spectral ratio (H/V) method. While the soil dominant frequency values varied between 0.4 Hz and 10 Hz, the soil amplification factor changed between 1 and 10. Higher H/V values were acquired with lower frequency values. The vulnerability index (Kg) and shear strain parameters that are utilized to estimate the damage that may be caused by an earthquake were mapped. Especially in the west side of the study area, higher Kg values were observed. The shear strain map was created with 0.25 g, 0.50 g and 0.75 g bedrock accelerations, and soil types that lost elasticity during an earthquake were identified. The average shear wave velocity for the first 30 m (Vs30) was calculated. Finally, it was observed that the western part of the study area, which resulted in a higher period and higher H/V, higher Kg and lower Vs30 values, presents a higher risk of damage during an earthquake.

It is known that the site classifications are closely related to the damages caused by earthquakes in areas with increased seismic hazard. Additionally, another important parameter utilized to identify the damage is the Peak Ground Acceleration (PGA) value. While measurements and the GMPE are utilized to identify PGA values, site classification is usually conducted by using the Vs30 value. This study aims to identify the site classifications for Bursa province by using a different approach, namely, the H/V spectral ratio method based on the dominant periods. In this regard, 205 records belonging to 82 earthquakes recorded by 41 strong ground motion stations located in Bursa province were utilized. A mean H/V spectral ratio curve was developed for each station based on the Fourier and response spectra of these earthquake records. Generally, double or multiple peaks resulting from the site structure were observed in the H/V curves. Furthermore, for the station locations, the evaluations were conducted in accordance with the site classifications per the dominant period as it is suggested in the literature. The stations were identified as all of the site classifications suggested by (Zhao et al. Bull Seismol Soc Am 96:914-925, 2006), as SC-1, 2, 3 and 5 suggested by (Fukushima et al. J Earthquake Eng 11:712-724, 2007) and as CL I, II, III, IV and VII suggested by (Di Alessandro et al. Bull Seismol Soc Am 102:680-695, 2012). Additionally, various Spectral Acceleration estimations were made with different GMPE equations for scenario earthquakes, and the results were compared with the design spectra suggested by the Turkish Building Earthquake Code (TBEC 2018). As a result of the study, the H/V spectral curves were generated according to both Fourier and response spectra; using a great number of earthquake data, the hazard was assessed by the soil dominant period-based for the first time in Bursa province.