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This paper is aimed at serving the needs of structural engineering designers of an important structure (or a group of structures located on the same site) who is seeking guidance on how to obtain accelerograms and/or derive response spectra that accurately represent the site subsoil conditions as informed by the borelogs. The presented site-specific seismic action model may be used to replace the default seismic action model stipulated for the designated site class. Presented in this article is a procedure for generating soil surface motions in an earthquake, and their associated site-specific response spectra, taking into account details of the soil layers. Dynamic site response analyses are involved. The conditional mean spectrum methodology is employed for selecting and scaling accelerograms for obtaining input motion on bedrock. The selection depends on the natural period of both the site and the structure. Multiple borelogs taken from within the same site are analysed to identify the critical soil column models without having to conduct site response analysis on every borelog. The technique for simplifying the soil layers utilising the shear strain profile is introduced to further cut down on the time of analyses. The procedures described in this article have been written into a web-based program that is freely accessible to engineering practitioners.

The seismic effects of complex, deep, and inhomogeneous sites constitute a significant research topic. Utilizing geological borehole data from the Suzhou urban area, a refined 2D finite element model with nonuniform meshes of a stratigraphic section crossing the Suzhou region was established. Within the ABAQUS/explicit framework, the spatial inhomogeneity of soils, including the spatial variation of S-wave velocity structures, was considered in detail. The nonlinear and hysteretic stress–strain relationship of soil was characterized using a non-Masing constitutive model. Ricker wavelets with varying peak times, peak frequencies ( f p ), and amplitudes were selected as input bedrock motions. The analysis revealed the spatial distribution characteristics of 2D nonlinear seismic effects on the surface of deep and complex sedimentary layers. The surface peak ground acceleration (PGA) amplification coefficients initially increased and then decreased as f p increases. The surface PGA amplification was most pronounced when the f p is close to the site fundamental frequency. Additionally, when f p  = 0.1 Hz, the surface PGA amplification was found to depend solely on the level of bedrock seismic shaking, with amplification factors ranging from 1.20 to 1.40. Furthermore, the ensemble empirical mode decomposition components of seismic site responses can intuitively reveal the variations in time–frequency and time–energy characteristics of Ricker wavelets as they propagate upward from bedrock to surface.

This study investigates the seismic response of thirty meter deep soil profiles with varying compositions and layering sequences, including homogeneous clay and sand profiles and partially layered profiles composed of 22.5 m of clay over 7.5 m of sand, 7.5 m of clay over 22.5 m of sand, 22.5 m of sand over 7.5 m of clay, 7.5 m of sand over 22.5 m of clay, and evenly layered profiles with 15 m of clay over 15 m of sand or 15 m of sand over 15 m of clay. Nonlinear one-dimensional ground response analyses were performed using RSSeismic software, applying seven strong ground motions scaled to peak ground acceleration levels of 0.10 g, 0.25 g, and 0.50 g. The results demonstrate that seismic amplification is strongly governed by the soil type located at the ground surface, impedance contrasts between adjacent layers, thickness distribution of soft and stiff materials, and nonlinear stiffness degradation under increasing shaking intensity. Profiles with clay at the surface consistently produce higher amplification and longer period response because of greater modulus degradation, whereas sand dominated surfaces generate stronger short period amplification with reduced nonlinear softening. In partially layered profiles the largest amplification, approximately 5.67, occurred when a thin clay layer overlies thick sand in Profile 06, while the lowest amplification, between about 1.36 and 1.88, occurred in profiles with thick sand at the surface such as Profile 04. Deamplification zones were also identified, varying across profiles and shaking levels. These observations highlight the critical importance of accurately characterizing soil stratigraphy for reliable site-specific seismic hazard assessment and earthquake resistant design.

The present study addresses verification of average seismic shear-wave velocity from the surface to a depth of 30 m (V S30 ) as a suitable proxy for a seismic amplification. For this purpose, we used instrumentally homogeneous and spatially dense seismic network WEBNET (West Bohemia Seismic Network), designed to monitor an intraplate earthquake swarm activity in the West Bohemia/Vogtland region (Czech Republic/Germany). Using a Multichannel analysis of surface waves (MASW) shear-wave velocity models and parameters V S30 and H 800  (depth of V s  > 800 m/s) were obtained at 17 WEBNET sites. V S30 were compared with (i) H 800 and (ii) determined bedrock densities. To understand the relation between V S30 and site amplification, V S30 values were correlated with amplitudes of two earthquakes: (1) Mw 6.4 Petrinja, Croatia (12/2020) and (2) Mw 4.2 SE of Vienna, Austria (03/2021) both recorded by the WEBNET. The correlation analysis examined four categories of seismic waves in nine frequency windows and described the relation between amplification and V S30 using newly defined regression model. The results show that for the regression model, the frequency window with the highest correlation is in the 1–3 Hz range, and this dependence is statistically best observed in the full wave record. The amplification generally decreases with increasing V S30 . However, a large scatter in amplification within Eurocode 8 category B is observed. Based on the observations a new general approach is put forward to finely indicate the relation between amplification and V S30 and the use of other site proxies is discussed.

The horizontal-to-vertical spectral ratio (HVSR) has been extensively used in site characterization utilizing recordings from microtremor and earthquake in recent years. This method is proposed based on ground pulsation, and then it has been applied to both S-wave and ambient noise, accordingly, in practical application also different. The main applications of HVSR are site classification, site effect study, mineral exploration, and acquisition of underground average shear-wave velocity structure. In site response estimates, the use of microtremors has been introduced long ago in Japan, while it has long been very controversial in this research area, as there are several studies reporting difficulties in recognizing the source effects from the pure site effects in noise recordings, as well as discrepancies between noise and earthquake recordings. In practice, the most reliable way is the borehole data, and the theoretical site response results were compared with the HVSR using shear wave to describe site response. This paper summarizes the applications of the HVSR method and draws conclusions that HVSR has been well applied in many fields at present, and it is expected to have a wider application in more fields according to its advantages.

This study evaluated epistemic uncertainty in shear-wave velocity (Vs) profiles and variability in shear-wave quality factor (Qs) profiles across broadband frequencies to investigate characteristics and controlling factors of seismic site response at a crystalline bedrock site. This study utilized deep borehole data down to the seismological bedrock at a depth of 2000 m. Multiple invasive measurements were conducted to estimate the Vs profiles. Three-component seismometers were installed at depths of 5, 160, 500, and 2000 m for Qs profiling. A logic tree with 128 analysis patterns was employed to capture the frequency-dependent percentiles of the amplification factor (AF) and the Qs parameter through spectral ratio Qs inversions. AFs from depths of 2000 m to 5 m showed the attenuation effect was dominant in the frequency range above 1 Hz. Sensitivity analysis revealed the dominant effects of the Qs profile below 2 Hz and above 15 Hz and the significant effects of the Vs profile at 2–15 Hz. The median AF curves were robust due to multiple invasive measurements and constraints from reliable seismic records. Local site responses captured from the 2000- m borehole station are expected to contribute to seismic hazard assessments as a reference of crystalline bedrock sites.

Volcanic environments are often characterized by frequent explosive activity and complex ground features. Explosions can couple into the ground, triggering ground response (GR) influenced by near-surface properties. While GR resulting from seismic input is well-studied, GR generated by air-to-ground coupling of volcanic explosions remains poorly understood. Investigating this phenomenon is crucial for understanding near-surface material dynamics and improving volcanic hazard assessments. To study explosion-induced GR, a multi-parametric network was deployed near Mt. Etna’s summit craters in 2019, where GR had been previously observed. The network includes broadband seismometers, infrasound sensors, and a fibre optic cable for distributed dynamic strain sensing (DDSS). Over 65,000 explosions were recorded, with some triggering high-frequency GR signals (10–50 Hz) in the DDSS data. These high-frequency signals, embedded in low-frequency explosions (0.7–4 Hz), amplify upon coupling into the ground. We also classified the explosions using waveform similarity, and GR signals were analysed using an adapted approach incorporating temporal and spatial dimensions. Strain rate vs. pressure rate relationships derived from classified signals were interpreted in terms of either linear elastic or hyperelastic near-surface behaviour. Despite no clear consensus towards which mechanical model describes best the ground behaviour, we suggest a nonlinear site amplification driven by mechanical particle interactions rather than near-surface layer resonance.

Quantitative estimation of seismic risk over a region requires both an underlying probabilistic seismic hazard model and a means to characterise shallow site response over a large scale. The 2020 European Seismic Risk Model (ESRM20) builds on the 2020 European Seismic Hazard Model (ESHM20), requiring additional information to firstly parameterise the local site condition across all of Europe, and subsequently determine its influence on the prediction of seismic ground motion. Initially, a harmonised digital geological database for Europe is compiled, alongside a model of topographic/bathymetric elevation and a database of 30 m averaged shearwave velocity measurements ( V S 30 ), in order to produce separate 30 arc-second maps of inferred V S 30 based on topography and on geology. We then capitalise on a large database of seismic recording stations in Europe for which site-to-site ground motion residuals ( δ S 2 S S ) have been determined with respect to the shallow crustal ground motion model used in the ESHM20. These residuals allow us to incorporate site amplification functions into the European GMM calibrated upon either observed or inferred V S 30 , or on the European geology and topography models. We present the resulting pan-European seismic site amplification model and assess its impact on seismic hazard and risk compared against other approaches. The new site amplification model fulfils the requirements of the ESRM20 and, providing uncertainty is fully propagated, yields estimates of seismic hazard and risk at a large space scale that may be comparable to other methods often applied at local/urban scale where better-constrained site information is available.

The choice of stiffness profile can be crucial in a site response analysis. This research aims to study site response predictions at the large-scale seismic test site in Lotung, Taiwan, employing three different approaches to choosing the stiffness profile in nonlinear and equivalent linear analyses. These approaches consider point average, layer average, and deposit average stiffness profiles. One strong and one weak earthquake event recorded at the site are simulated with these three stiffness profile approaches. Moreover, the stiffness profiles are tested under sets of seven modified real input motions (selected from the European Strong-Motion Database) at various seismic intensity levels. The results indicate that the different stiffness profiles have a minimal effect on the nonlinear site response predictions, in particular for input motions having a PGA greater than or equal to 0.05 g. The spectral acceleration values and PGA and shear strain profiles from nonlinear site response analyses change negligibly when using different approaches to derive the stiffness profile. In the equivalent linear site response analysis, the spectral acceleration predictions are strongly influenced by the stiffness profile approach, regardless of the PGA level of the input motions. The stiffness profile has a more significant role in equivalent linear site response analysis than in nonlinear site response analysis. Therefore, the point average stiffness profile should be used in equivalent linear site response analysis.

In civil engineering, one of the main problems is the stability of structures. Blast vibrations can be one of several elements influencing the stability of these structures. In order to prevent any effects on the structures, the maximum suggested values of the peak particle velocity and frequency from the blast are generally determined using the existing appropriate government rules and industry standards as reference. In this paper, the effect of these vibration on the site response has been investigated. Parameters such as peak ground acceleration, Pseudo spectral acceleration and maximum stress and strain has been compared for two different soil models. The results indicate that the soft soil has a significant impact and amplifies the input parameters considerably.