This paper reviews recent work on energy-based methodologies for estimating pore water pressure rise and the timing of initial soil liquefaction. Unlike stress-based methods, energy-based approaches use a scalar, cumulative parameter—making them well suited to modeling pore pressure buildup and the timing of liquefaction onset. The rise in pore pressure and onset of liquefaction can be estimated by summing cumulative dissipated hysteretic strain energy normalized by effective stress, which correlates strongly with the pore-pressure ratio r_u . As such,, normalized energy is a complex parameter that combines the demand and capacity sides of the liquefaction problem into one term. Energy dissipated beyond the liquefaction boundary maintains r_u=1.0 , and likely is correlated with the potentially large shear and volumetric strains associated with liquefaction damage. However, one practical challenge of applying the method is that it requires empirical hysteretic relationships between normalized cumulative energy and excess pore pressure ratio, that are difficult to obtain in the laboratory and almost never available in the field. Proxy models for dissipated work—using Arias Intensity, Cumulative Absolute Velocity (CAV), and soil parameters, relative density or the state parameter of Been and Jeffries (1985)—appear to be the most practical path forward. However, these parameters are hampered by their elevated predictive uncertainties. The key benefit of the scalar and cumulative nature of energy-based methods are that they lead to improved estimation of liquefaction timing. Therefore, we can use just the the post-initial liquefaction time history to correlate with shear and volumetric strains. Three independent methods are currently used: the hysteretic strain-energy method, the Spectral Energy Ratio (SER) method, and Arias Intensity timing. These approaches aim to link total energy demand (Arias Intensity) to partial absorbed work (hysteretic strain energy). Parallel research investigates shear and volumetric strains before, during, and after r_u=1.0 . Liquefaction timing estimates based on Arias Intensity and SER can recalibrate soil models for G/G_max , energy absorption, and pore pressure rise. Future work will establish relationships between hysteretic strain energy, Arias Intensity, and CAV with field penetration resistance, relative density, and initial shear stress. If successful, simplified energy demand parameters could assess liquefaction potential and act as proxies for dissipated work. Ultimately, well-documented case histories and robust proxy models will provide the foundation for energy-based, performance-oriented liquefaction assessment methods.

The 1964 M7.5 Niigata earthquake remains one of the most significant natural laboratories for understanding seismic-induced soil liquefaction and its dependence on geological setting. Among global field case histories, Niigata stands out for the exceptional documentation of liquefaction triggering, lateral spread displacements, and soil-structure interaction. This paper reexamines the event from an engineering-geologic perspective, emphasizing how Holocene coastal and fluvial depositional processes beneath the Echigo Plain controlled the spatial and stratigraphic distribution of liquefaction during the 1964 earthquake. The most severe ground deformations occurred in fluvially reworked sands derived from three major Holocene dune and barrier island systems (CSD1,2,3) formed along the paleo-shoreline of the Sea of Japan. The largest of these, a mid-Holocene transgressive barrier complex deposited to a thickness of 50-60 m of beach and aeolian sand between 8 and 5 ka B.P., now lies buried 5-8 km inland beneath fine-grained alluvial deposits. Tectonic downwarping and deltaic progradation by the Shinano and Agano rivers redistributed these sands into loose, saturated fluvial facies beneath modern Niigata city. Quantitative geotechnical analyses demonstrate that liquefaction occurs within these reworked Holocene units rather than anthropogenic fills.

Investigating the seismic response of earth embankment dams is crucial for assessing the safety of existing dams and guiding new design procedures. The dam fundamental frequency (f(0)) is a critical parameter in the dynamic response of dams and can be evaluated using seismic recordings through Horizontal-to-Vertical Spectral Ratio (HVSR) and Standard Spectral Ratio (SSR) methods. This study focuses on assessing the vibration characteristics of Briones Dam, a 78 m-tall earth embankment dam located in the Bay Area in Northern California. First, earthquake-based Horizontal-to-Vertical Spectral Ratio (eHVSR) was estimated by dividing the horizontal records by the vertical components, and the SSR was determined by comparing crest recordings with those from the abutment. Additionally, a field test program was conducted to collect ambient noise measurements at Briones Dam, allowing for the calculation of microtremor-based HVSR. The fundamental frequency was estimated using three empirical methods: mHVSR (0.7-1 Hz), eHVSR (0.9-1.1 Hz), and SSR (1.2 Hz). The median fundamental frequency of the dam is estimated to be approximately 1 Hz at the center of the dam crest. The slight variations among these three methods suggest the need for further investigations that consider the geological and geotechnical conditions of the dam. (c) 2025 Japanese Geotechnical Society. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

The magnitude (Mw) 8.3 Tokachi-oki earthquake occurred in September 2003, causing extensive damage in Hokkaido, Japan, and triggering extensive soil liquefaction in the region. The Port of Kushiro was one of the locations where surficial evidence of liquefaction was observed but was also a well-instrumented location with four pore-water pressure transducers installed in the backfill of the quay wall. However, all of the sensors malfunctioned during the earthquake. As a result, the pore-water pressure response recorded by those sensors were inaccurate and unusable with regard to evaluating liquefaction triggering and extent. This study introduced the energy-based soil liquefaction evaluation to estimate the excess pore water pressure responses at the Port of Kushiro based on the cumulative strain energy of the soil during the 2003 Tokachi-oki earthquake. In order to apply the energy-based method to this case history, this study explored the empirical equation describing a relationship between normalized cumulative energy and excess pore water pressure ratio while incorporating the bidirectional shaking effect on strain energy development. Although the energy-based method allowed for the estimation of the time needed to trigger liquefaction at a target site, it was derived using the empirical coefficients that were developed for a different soil from those at the site of interest. This indicated that an adjustment to the estimated timing of liquefaction was needed, which was accomplished by additional evaluation through a Stockwell transform and Arias intensity-based liquefaction assessment. Both procedures indicated a similar timing of liquefaction at the site. Based on the updated time of liquefaction triggering, the empirical coefficient was recalibrated to estimate the excess pore water pressure ratio, and the result provided reasonable excess pore water pressure responses at the backfill of the Port of Kushiro during the 2003 Tokachi-oki earthquake.

The evaluation of the excess pore water pressure ratio (ru), the ratio of the excess pore water pressure of the soil, is a defining approach to assessing liquefaction occurrence. Rarely is ru measured, so surficial observations of sand boils, fissures, and soil settlements have provided indirect evidence of liquefaction occurrence in case histories. Acceleration responses during undrained cyclic loadings incorporate shear strain and stress responses of the liquefied soil. Therefore, the use of acceleration responses can provide another indirect indication of liquefaction as the sudden drop in the frequency in the time-frequency domain in acceleration records. This study aimed to develop strain-based and energy-based methods for estimating the pore water pressure buildup based on the acceleration responses of liquefiable sand layers. The strain-based method linked the liquefaction-induced shear strain of the soil with ru through the shear modulus that is a function of the effective stress. An alternative approach used an energy-based method that linked pore-pressure generation with the energy dissipated in the soil. Centrifuge model tests for the liquefaction of soil were used to develop and validate the two methods, and these were applied to a case history, the 1987 Superstition Hill earthquake at the Wildlife site, for validation. To capture the variation of ru from its contractive to dilative responses, the amount of ru drop was estimated based on the peak shear stress when dilation spikes occurred. For the energy-based method, the centrifuge test results were used to derive empirical relations between ru and cumulative dissipated energy done by liquefiable soil. The estimated ru time-histories from the established methods were consistent with the measured responses in the centrifuge tests and the case history.

ABSTRACT 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.

The time-averaged shear-wave velocity in the top 30 m, V S 30 , is used to represent the site condition in many ground-motion models (GMMs). Regionalized GMMs account for regional differences in the ln (V S 30 ) scaling by including region-specific coefficients for the site term. For example, recent GMMs developed for subduction zone earthquakes as part of the Next Generation Attenuation-Subduction (NGA-Sub) project include region-specific V S 30 scaling for seven regions: South America, Central America, Japan, New Zealand, Taiwan, Cascadia (Pacific Northwest America), and Alaska. Of these seven regions, South America has the largest within-event standard deviation. One cause for the larger within-event standard deviation is a weaker relation between V S 30 and the site term in South America compared to other regions. A cause for this weak correlation is that most of the V S 30 values for the South American region in the NGA-Sub data set are based on proxies. The relation between V S 30 and the site term improves significantly for periods less than 1 s if only stations with measured V S 30 are considered, but the correlation is weak for periods greater than 1 s even for stations with measured V S 30 , indicating that, for the South America region, V S 30 is not well correlated with the deeper shear-wave velocity profile that controls the long-period amplification. To improve the site terms for South America, we develop a model based on the horizontal-to-vertical spectral ratio (HVSR) from microtremors, similar to the approach used by Pinilla-Ramos et al. (2022) for California. The data set includes 660 recordings from 51 earthquakes recorded at 274 sites. The site-term model includes the period- dependent HVSR amplitude and the geometric mean of the average HVSR amplitude over the frequency band of 0.25 to 15 Hz. Including these two parameters reduces the standard deviation of site-specific site terms over the period range 0.3-3 s, with the largest reduction in the period range 1-2 s. This site-term model can be incorporated into subduction GMMs and implemented in probabilistic seismic hazard analyses for South America.

Geotechnical engineers often participate in projects that involve Building Information Modeling, or BIM, digital-twin engineering design, and even just classical geotechnical studies. Therefore, it's helpful to know about the latest advanced quantitative methods that can best characterize topography and changes to structural surfaces. An array of new, remote sensing tools utilizes the most transmissive portions of the electromagnetic spectrum, EM, to map surfaces and surface change at millimeter-to-centimeter accuracy.

The vertical factor of safety (FSv) of shallow foundations has been widely used for static design and seismic design. The FSv is a function of the bearing capacity of the system and the vertically applied load from the structure and foundation loads to the soil and foundation interface. However, the structure-to-foundation mass ratio (MR) can be different for the systems presenting the same FSv. The dynamic responses of the structure and foundation system depend on the MR as it develops dissimilar inertial behaviors from the structure and foundation. In this study, the effect of MR on the structure and foundation responses was evaluated using an analytical model that enables influence of the nonlinearity of the soil on the modeled foundation base and structure. For systems with the same FSv under identical input loading conditions, the inertial behavior of heavy foundations had a larger acceleration response than the lighter foundations. Consequently, MR should be considered for evaluating dynamic soil-foundation-structure interaction problems.

Following the M7.0 strike-slip earthquake near Kumamoto, Japan, in April of 2016, most geotechnical engineering experts believed that there would be significant soil liquefaction and liquefaction-induced infrastructure damage observed in the densely populated city of Kumamoto during the post-event engineering reconnaissance. This belief was driven by several factors including the young geologic environment, alluvially deposited soils, a predominance of loose sandy soils documented in publicly available boring logs throughout the region, and the high intensity ground motions observed from the earthquake. To the surprise of many of the researchers, soil liquefaction occurred both less frequently and less severely than expected. This paper summarizes findings from our field, laboratory, and simplified analytical studies common to engineering practice to assess the lower occurrence of liquefaction. Measured in situ SPT and CPT resistance values were evaluated with current liquefaction triggering procedures. Minimally disturbed samples were subjected to cyclic triaxial testing. Furthermore, an extensive literature review on Kumamoto volcanic soils was performed. Our findings suggest that current liquefaction triggering procedures over-predict liquefaction frequency and effects in alluvially deposited volcanic soils. Volcanic soils were found to possess properties of soil crushability, high fines content, moderate plasticity, and unanticipated organic constituents. Cyclic triaxial tests confirm the high liquefaction resistance of these soils. Moving forward, geotechnical engineers should holistically consider the soil's mineralogy and geology before relying solely on simplified liquefaction triggering procedures when evaluating volcanic soils for liquefaction.

The small-strain shear wave velocity (V-s) is a means to assess the triggering of seismic soil liquefaction since the early 1990s, and the size and quality of these data sets have grown enormously in the past decades. Based on these data, researchers from 1991 to the present have developed V-s-based seismic soil liquefaction triggering relationships. The authors revisited the V-s-based database to update the case histories with the current state of knowledge and include new case histories (e. g., 2011 Tohoku earthquake, 2010-2011 New Zealand-Canterbury earthquakes, etc.). This paper presents the updated Vs-based database, along with the details and statistics of the case history database. The updated database consists of (1) 537 case histories, (2) new earthquake events, (3) multiple inversion method, (4) assessment of nearby standard penetration test (SPT) and cone penetration test (CPT) data, (5) dispersion curves, (6) multiple shear wave velocity profiles, (7) digitized Vs profiles of the literature case histories, (8) implementation of the improved selection of unit weight, (9) new parameters related to site information (e.g., V-s30m, etc.), (10) standard protocol to process data in an unbiased manner, (11) uncertainties of each input parameter, and (12) and geological site classification. Every input parameter was revisited, reanalyzed, and updated. The new database is organized to develop new probabilistic shear wave velocity-based seismic soil liquefaction triggering relationships using Bayesian analysis and system reliability methods.

ABSTRACT 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 standard penetration test (SPT) has been used to assess the triggering of seismic soil liquefaction since the early 1970s. The currently available liquefaction case history database is updated and extended with the case histories from recent earthquake events. An updated database, which consists of 405 case histories from several recent major earthquake events (e.g., 1999 Chi-Chi, 2008 Achaia-Ilia, 2010 El-Mayor, 2011 Van, 2011 Tohoku, 2011 Christchurch, 2012 Emilia-Romagna, 2016 Kaikoura, 2018 Jia Sian, etc.) was compiled. This new SPT-based field case history database consists of (1) 405 case histories from (2) 33 new earthquake events, (3) with different faulting mechanisms including strike-slip, normal, reverse, and subduction earthquake events, and introduced (4) new event parameters (e.g., Rrup, Rjb, ztor, etc.), (5) gravelly and silty critical layers with the introduction of new correction terms (e.g., gravel correction), (6) fully digitized borehole information, GPS coordinates, and comparative assessment of new screening criteria with the nearby CPT and Vs data, (7) site response and deconvolution analyses at strong ground motion liquefaction sites to estimate CSR, (8) new parameters related to ground motion and site information (e.g., event type, rupture distance, Vs30m, etc.), (9) a description of geological settings, and (10) new stress (CN), energy (CE), and rod length (CR) correction terms. Within the confines of this manuscript, this database compilation and processing details will be presented. The resulting database is to be used to develop new probability-based liquefaction triggering relationships.

For longer than four decades, the current practice for liquefaction triggering engineering assessments have been dominated by case history-based deterministic and probabilistic models. The predictive model proposals have been constituted based on different sets of case histories concerning in-situ test indices, namely standard penetration test (SPT) N value, cone penetration test (CPT) q, and shear-wave velocity (Vs), etc. The present study uses the databases of Cetin et al., Moss et al., and Kayen et al. together to develop a unified liquefaction triggering predictive model within a probabilistic framework. The scope concentrates on the illustrative introduction of the proposed unified reliability-based framework along with the comparative presentation of model predictions. The unified model enables a joint assessment of liquefaction performance predictions at sites, where different in-situ test indices are used individually or jointly to characterize the soil resistance against liquefaction.

Landslides are common geohazards associated with natural drivers such as precipitation, land degradation, toe erosion by rivers and wave attack, and ground shaking. On the other hand, human alterations such as inundation by water impoundment or rapid drawdown may also destabilize the surrounding slopes. The Guobu slope is an ancient rockslide on the banks of the Laxiwa hydropower station reservoir (China), which reactivated during the reservoir impoundment in 2009. We extracted three-dimensional surface displacements with azimuth and range radar interferometry using European Space Agency's Copernicus Sentinel-1 and German Aerospace Center's TerraSAR-X data during 20152019. The upper part of the Guobu rockslide is characterized by toppling and is mostly subsiding with maximum rates over 0.4 m/yr and 0.7 m/yr in the vertical and horizontal directions, respectively. During filling of the reservoir prior to 2014, there was a long-wavelength in-phase response between rising reservoir level and GPS-observed increased slope movements. After the reservoir water level stabilized from 2015 to 2019, the slide movement became seasonal and we see a correlation between rainfall and landslide movement. These observations suggest that the slide motion is now primarily controlled by rainfall. The spatiotemporal landslide displacements allow us to estimate the hydraulic diffusivity of the rock mass, to be on the order (similar to 1.05 x 10(-7) m(2)/s) and the thickness of the moving rock mass (similar to 200 m). Our results demonstrate that InSAR is a useful tool for monitoring the rockslide movement as a function of seasonal precipitation.

A collection of points representing an object in space is commonly called a point cloud. There are several techniques for collecting point clouds. This research is focused on a comparison study of two approaches: (1) collecting point clouds with a surveying grade terrestrial laser scanner (TLS) and (2) generating point clouds from drone-taken still images by utilizing Structure-from-Motion (SFM) technique. The paper's main objective is to compare the generated point clouds to each other and show the advantages and disadvantages of both techniques for structural health monitoring of bridges. To achieve the goal of the paper, we selected a pedestrian bridge for a comparison study. For simplicity, the study was limited to a single-span bridge. The bridge we studied is a composite steel and reinforced concrete (RC) bridge with a curved deck. A terrestrial laser scanner was used to scan the bridge from several positions, and point clouds were registered based on point-cloud to point-cloud matching. No targets were used during the collection of the point clouds by the laser scanner. In addition, still images of both bridges were taken by a drone. Based on a quantitative comparison of the results, the paper discusses the pros and cons of both approaches.

First posted July 14, 2020 For additional information, contact: Contact InformationPacific Coastal & Marine Science CenterU.S. Geological SurveyPacific Science Center2885 Mission St.Santa Cruz, CA 95060 The greater San Francisco Bay estuary, prior to human intervention, encompassed about 2,200 km2 of tidal and salt marshes. Over time, these areas became increasingly diked, developed, and altered from their natural state. In addition, natural forces are always driving a continually shifting equilibrium.This study area, the Corte Madera marshes, is a tidal marsh or wetland located in southeastern Marin County, and it borders an embayment of central San Francisco Bay along about 2.8 km of shoreline. Most of this shoreline is located within the Corte Madera Marsh Ecological Reserve, managed by the California Department of Fish and Wildlife. Other areas within the marsh include (1) unincorporated Greenbrae (at the boardwalk), (2) diked land (that is, isolated from tidal action) owned by the Golden Gate Bridge Highway and Transportation District, and (3) urbanized areas such as in the Mariner Cove subdivision of Corte Madera. The present tidal marsh area was historically subdivided into the following informally named tracts, listed from north to south: Heerdt marsh, north Muzzi marsh, inner and outer Muzzi marshes, Marta’s marsh, and Triangle marsh.The purpose of this study is to derive the magnitudes and rates of shoreline change (both erosion and accretion) for the Corte Madera shoreline, with particular emphasis on the time period from 1931 to 2016. The rates of change are then related to different shoreline types (that is, natural or diked) and (or) locations on the shoreline.

At landfall in Yabucoa, Puerto Rico, on September 20, 2017, the National Hurricane Center classified Hurricane Maria as a strong Category 4 hurricane on the Saffir-Simpson hurricane wind scale. This paper summarizes the geotechnical impacts and consequences from Maria, documented by the Geotechnical Extreme Events Reconnaissance (GEER) team sent to the island in its aftermath. The intense rainfall and strong winds associated with Maria directly or indirectly resulted in over 3,000 fatalities, severe infrastructure loss, over 40,000 landslides, and considerable coastal erosion in Puerto Rico. Hurricane Irma preceded Hurricane Maria by two weeks and this paper addresses the importance of antecedent rainfall and geomorphology on the magnitude of damage. Geotechnical impacts described in the paper include coastal erosion events, bridge abutment scour, the impact of debris flows on the island's highway system, and foundation failures. The geotechnical failures presented in our article provide insight on the likely modes of failure when major hurricanes affect slopes that have been pre-soaked and are thus especially vulnerable to geotechnical failures. Since global warming will likely increase the intensity and frequency of extreme events like Hurricane Maria, understanding the impacts and aftermath of Maria in Puerto Rico should assist the engineering community in addressing geotechnical vulnerabilities, as well as improve design and construction practices, to improve resiliency.