Shear-wave velocity (Vs) offers a means to determine the seismic resistance of soil to liquefaction by a fundamental soil property. This paper presents the results of an 11-year international project to gather new Vs site data and develop probabilistic correlations for seismic soil liquefaction occurrence. Toward that objective, shear-wave velocity test sites were identified, and measurements made for 301 new liquefaction field case histories in China, Japan, Taiwan, Greece, and the United States over a decade. The majority of these new case histories reoccupy those previously investigated by penetration testing. These new data are combined with previously published case histories to build a global catalog of 422 case histories of Vs liquefaction performance. Bayesian regression and structural reliability methods facilitate a probabilistic treatment of the Vs catalog for performance-based engineering applications. Where possible, uncertainties of the variables comprising both the seismic demand an...

The horizontal‐to‐vertical spectral ratios from microtremor (mHVSR) data obtained at 196 seismic stations in California are used to evaluate three alternative microtremor‐based proxies for site amplification for use in ground‐motion models (GMMs): the site fundamental period (⁠ $f0$⁠), the period‐dependent amplitude of the mHVSR(T), and the normalized amplitude of the mHVSR(T). The alternative parameters are evaluated for the sites with and without measurements of $VS30$⁠. If a $VS30$ measurement is not available for a site, then $f0$ has the highest correlation with the site amplification for short periods (T <1 s) and the normalized amplitude of the mHVSR(T) has the highest correlation for long periods (T ≥1 s). If a measurement of the $VS30$ is available for a site, then the normalized amplitude of the mHVSR(T) has the highest correlation for the site amplification not explained by $VS30$ for all periods. For both cases, the correlations are strongest at the longer periods as mHVSR(T) measurements excel at providing valuable information for sites with long‐period amplification due to the deeper velocity structure. In particular, for sites with a $VS30$ measurement, the normalized mHVSR(T) amplitude provides more information about the long‐period site terms than the basin depth currently used in GMMs. Empirical models of the median and standard deviation of the site terms based on the normalized mHVSR(T) curves are developed for the two cases. These models can be used directly in the ASK14 GMM to modify the median and aleatory standard deviation or they can be used to estimate the site‐specific site term in the context of a partially nonergodic GMM. Including the mHVSR(T) measurement can have a significant effect on estimates of the ground motion at a site: the range 5%–95% on the observed HVSR(T) values corresponds to factors of 0.6–1.6 for the median spectral acceleration for periods between 0.5 and 4 s.

The recent Japanese earthquake and tsunami is one of several recent, destructive events that has provided critical engineering information regarding the performance of buildings, bridges, walls, roadways, etc. during intense loading. 3D laser scanning technology provides a valuable tool to acquire perishable information and preserve the scene digitally for post-disaster assessment. This paper discusses the challenges and benefits for use of 3D laser scanning on post-disaster reconnaissance efforts. This paper also focuses on special considerations when performing scanning work in post-disaster environments. Because of the limited time available to make critical decisions, it is important for personnel to know optimal procedures during planning, field reconnaissance, collaboration, data acquisition, processing, and analysis. Examples from recent events illustrate the power of this revolutionary tool in forensic investigations.

We describe an Italian database of strong ground motion recordings and databanks delineating conditions at the instrument sites and characteristics of the seismic sources. The strong motion database consists of 247 corrected recordings from 89 earthquakes and 101 recording stations. Uncorrected recordings were drawn from public web sites and processed on a record-by-record basis using a procedure utilized in the Next-Generation Attenuation (NGA) project to remove instrument resonances, minimize noise effects through low- and high-pass filtering, and baseline correction. The number of available uncorrected recordings was reduced by 52% (mostly because of s-triggers) to arrive at the 247 recordings in the database. The site databank includes for every recording site the surface geology, a measurement or estimate of average shear wave velocity in the upper 30 m (Vs30), and information on instrument housing. Of the 89 sites, 39 have on-site velocity measurements (17 of which were performed as part of this study using SASW techniques). For remaining sites, we estimate Vs30 based on measurements on similar geologic conditions where available. Where no local velocity measurements are available, correlations with surface geology are used. Source parameters are drawn from databanks maintained (and recently updated) by Istituto Nazionale di Geofisica e Vulcanologia and include hypocenter location and magnitude for small events (M 5.5) and finite source parameters for larger events

A duration ground‐motion model for crustal earthquakes based on the normalized Arias intensity (⁠ $IA$⁠) is developed. Two sets of seismological simulations are used to constrain the form and scaling of the duration model. Simulations using a 3D crustal model show that an additive model for the source, path, and site terms captures the physical behavior of duration better than a multiplicative model for the site term. Stochastic finite‐fault simulations are used to constrain the saturation of the large‐magnitude scaling at short distances. The duration model is developed in two parts: a duration model for the time interval between 5% and 75% of the normalized Arias intensity (⁠ $D5−75$⁠) and a duration model for the ratio of the $D5−X/D5−75$ duration for X values from 10 to 95. Together, these two models provide a more complete description of the evolution of the seismic energy with time than a single duration metric. A new aspect of the statistical model for duration is the inclusion of a random effect for the path term in addition to random effects for the source and site terms. The source and site random effects are modeled as scale factors on the duration, whereas the path‐term random effect is a scale factor on the distance slope. The distribution of the duration residuals has a skewness that is between the skewness of a lognormal distribution and the symmetry of a normal distribution. The final duration aleatory variability is modeled by a power‐normal distribution with an exponent of 0.3, which accounts for the amplitude dependence of the aleatory variability of the duration with smaller aleatory variability for large‐magnitude events and larger aleatory variability for small‐magnitude events as compared to the variability from a lognormal distribution.