Ellen Rathje

University of Texas at Austin | UT · Department of Civil, Architectural & Environmental Engineering

This article presents a suite of response spectrum (RS) and Fourier amplitude spectrum (FAS) site amplification models for Central and Eastern North America (CENA). The amplification database used in model development was produced through large-scale one-dimensional site response analyses and overcomes limitations of prior databases by providing br...

This paper presents a new set of site amplification models for Central and Eastern North America (CENA) through deep learning via Artificial Neural Network (ANN). The amplification models are for response spectral (RS) and Fourier amplitude spectral (FAS) ordinates. Compared to functions regressed using the same simulation data, the ANNs reduce bia...

We probabilistically assess the time-dependent seismic hazard and risk observed in Oklahoma due to wastewater disposal. The seismic hazard maps illustrate the incompatibility of the regional seismic provisions with the recent seismicity. During the peak of seismicity in 2015, the seismic risk was 275 times higher than the background level, with the...

This short note examines the downgoing wave effect and the appearance of pseudoresonances in downhole array data. It is demonstrated that pseudoresonances, distinct from the resonances associated with outcrop conditions, occur for sites with a shallow velocity contrast (VC) or with little to no VC. An approach is outlined to distinguish pseudoreson...

The slope of the Gutenberg-Richter law, i.e. the b-value, is believed and empirically observed to have a universal value of 1.0, following the natural size distribution of pre-existing defects in the earth’s crust [Langenbruch et al. 2014]. However, recent studies report fluctuating b-values between 1.3 - 1.6 in Oklahoma [e.g. Langenbruch & Zoback...

Small-strain damping profiles developed from geotechnical laboratory testing have been observed to be smaller than the damping inferred from the observed site amplification from downhole array recordings. This study investigates the high-frequency spectral decay parameter ( 0 ) of earthquake motions from soil sites and evaluates the use of 0 to con...

Wastewater disposal has been reported as the main cause of the recent surge in seismicity rates in several parts of Central United States, including Oklahoma. In this paper, we employ a new semi- empirical recurrence model to test the statistical significance of this prevailing hypothesis, The results show that the vast majority (78%) of the seismi...

This paper presents recommendation for nonlinear site amplification models in Central and Eastern North America (CENA), which are developed from one dimensional site response analyses results and accompanies linear site amplification model in companion paper. Two median nonlinear amplification models using identical functional forms are produced as...

The small-strain damping ratio (Dmin) is a key parameter in site response models and using values from laboratory tests tends to overpredict the site response because laboratory tests cannot capture the wave scattering effects that are present in the field. In this study, earthquake motions from four downhole array sites are used to investigate the...

Field observations are particularly important in geotechnical engineering, because it is difficult to replicate in the laboratory the response of soil deposits built by nature over thousands of years. Detailed mapping of damaged and undamaged areas provides the data for the well-documented case histories that drive the development of many current d...

This paper presents the development of large scale simulation based data sets used to inform new site amplification models for Central and Eastern North America (CENA). Linear elastic, equivalent linear, and nonlinear one-dimensional (1D) site response simulations of site conditions in CENA are employed. An analysis tree is introduced to capture th...

Site amplification models for Central and Eastern North America (CENA) are developed from simulation results presented in a companion paper. Linear and nonlinear amplification functions are developed for response spectral (RS) accelerations and smoothed Fourier amplitude spectra (FAS). Linear RS model components include ground motion scaling with 3...

The research investigates the seismic vulnerability of bridges in Texas by characterizing seismic hazards in the State, developing computational tools to estimate the likelihood of seismic damage to various bridge types, and providing Texas Department of Transportation (TxDOT) tools to inform post-earthquake response planning and decision-making.

This paper compares measured and predicted site response at the Garner Valley Downhole Array (GVDA) using a wide range of shear wave velocity (Vs) profiles developed from both borehole methods and inversion of surface wave data. Only low amplitude ground motions, resulting in approximately linear-viscoelastic site response between the downhole acce...

A ground motion model (GMM) tuned to the characteristics of the observed, and potentially induced, seismicity in Texas, Oklahoma, and Kansas is developed using a database of 4,528 ground motions recorded during 376 events of M w > 3.0 in the region. The GMM is derived using the referenced empirical approach with an existing Central and Eastern Nort...

Near-surface effects for a soft rock site (average shear-wave velocity of the top 30 m, Vs30 ≈ 800 m/s) for a proposed nuclear power station in the UK are integrated into the “bedrock” results of a probabilistic seismic hazard analysis (PSHA) by application of US Nuclear Regulatory Commission (USNRC) Approach 3 and employing a partially non-ergodic...

We present empirical linear site amplification models conditioned on time-averaged shear wave velocity in the upper 30 m (V S30 ) for central and eastern North America. The models are derived from ground motion data and site condition information from the NGA-East project and are intended for use with reference rock ground motion models. Site ampli...

Following the November 14 2016 Mw7.8 Kaikoura earthquake, field expeditions were undertaken using Unmanned Aerial Vehicles (UAVs) to map 25 sites of scientific interest with a plan area of 7.2 km2. A total of 23,172 images collected by the UAVs were used as input in Structure-from-Motion (SfM) to create 3D models of the target areas with a focus on...

Parts of Texas, Oklahoma, and Kansas have experienced increased rates of seismicity in recent years, providing new datasets of earthquake recordings to develop ground motion prediction models for this particular region of the Central and Eastern North America (CENA). This paper outlines a framework for using Artificial Neural Networks (ANNs) to dev...

Field observations are particularly important in geotechnical earthquake engineering because it is difficult to replicate in the laboratory the characteristics and response of soil deposits built by nature over thousands of years. Much of the data generated by an earthquake is perishable, so it is critical that it is collected soon after the event...

Equivalent linear (EQL) site response analysis commonly overdamps the ground response when the induced shear strains are large. The goal of this paper is to study the methods that can improve the performance of EQL site response predictions for large-intensity motions. The methods include modification of the modulus reduction curve to be consistent...

The seismic performance of slopes is typically evaluated based on the sliding displacement predicted to occur along a critical sliding surface. A probabilistic assessment of sliding displacement can account rigorously for the aleatory variability in earthquake ground shaking and in the dynamic response and sliding displacement predictions, providin...

The State of Texas has funded a new seismic network, the Texas Seismological Network (TexNet), which currently consists of 52 newly deployed stations. However, little information is available in Texas regarding the near surface shear wave velocity structure and site amplification. Thus, it is necessary to perform site characterization in order to i...

This paper presents large scale simulation-based modelling of site amplification in two regions, Central and Eastern North America (CENA) and the Western Unites States (WUS). For CENA, a parametric study is developed with 1.2 million 1-D site response analyses (0.58 million of each linear elastic and nonlinear analyses) to represent the variability...

Parts of Texas, Oklahoma, and Kansas have experienced increased rates of seismicity in recent years, providing new datasets of earthquake recordings to develop ground motion prediction models for this particular region of the Central and Eastern North America (CENA). This paper outlines a framework for using artificial neural networks (ANNs) to dev...

In 2016 two moderate earthquakes occurred in Oklahoma, the M 5.8 Pawnee earthquake and the M 5.0 Cushing earthquake. Strong ground shaking from these earthquakes was captured with seismometers and accelerometers across the state of Oklahoma, including 4 motions recorded within 10 km of the M 5.0 Cushing event. The motions recorded within 400 km are...

Liquefaction-induced lateral spreading during the 2011 Christchurch earthquake in New Zealand was severe and extensive, and data regarding the displacements associated with the lateral spreading provides an excellent opportunity to better understand the factors that influence these movements. Horizontal displacements measured from optical satellite...

Lateral spreads caused by liquefaction of underlying soils present a significant hazard to both overlying infrastructure such as roads, bridges, and buildings as well as subsurface infrastructure including pipelines, utilities, and tunnels. Assessing lateral spread displacements and spread extents using traditional field methods (i.e. manual measur...

Parts of Texas, Oklahoma, and Kansas have experienced increased rates of seismicity in recent years, providing new datasets of earthquake recordings to develop ground motion prediction models for this particular region of the Central and Eastern North America (CENA). This paper outlines a framework for using Artificial Neural Networks (ANNs) to dev...

Predicting the seismic performance of slopes involves an assessment of the expected permanent sliding displacement induced by ground shaking. Often, this analysis uses a deterministic approach that predicts sliding displacements using one level of ground shaking and the best-estimate slope properties (e.g., soil shear strengths). However, this appr...

Random vibration theory (RVT) site-response analysis is an attractive alternative to time-series (TS) analysis because it does not require input accelera-tion-time histories. A critical part of the RVT approach is computing the root mean square (rms) of the oscillator response from the Fourier amplitude spectrum and the key to this computation is t...

Random vibration theory (RVT) site-response analysis computes site-specific site amplification without the need for the specification of input time series (TS). A fundamental parameter in RVT analysis is the duration used when calculating the root mean square (rms) oscillator response (i.e., spectral acceleration) from the Fourier amplitude spectru...

The MW 7.8 14 November 2016 Kaikoura earthquake generated more than 10000 landslides over a total area of about 10000 km2, with the majority concentrated in a smaller area of about 3600 km2. The largest landslide triggered by the earthquake had an approximate volume of 20 (±2) M m3, with a runout distance of about 2.7 km, forming a dam on the Hapuk...

Earthquake-triggered ground failure, such as landsliding and liquefaction, can contribute significantly to losses, but our current ability to accurately include them in earthquake-hazard analyses is limited. The development of robust and widely applicable models requires access to numerous inventories of ground failures triggered by earthquakes tha...

Using satellite image pairs from the 2010-2011 Canterbury Earthquake Sequence (CES) in New Zealand, optical image correlation is used to measure horizontal displacements due to liquefaction-induced lateral spreading. Horizontal displacements as small as 0.2 to 0.3 m are accurately measured by optical image correlation at a spatial resolution of les...

The observed increase in seismicity in Texas, Oklahoma, and Kansas during the last ~5 years, has made the shear wave velocity characterization of these states increasingly pertinent. Due to the lack of in-situ shear wave velocity measurements, the P-wave seismogram method is used to develop estimates of the time averaged shear wave velocity of the...

The observed increase in seismicity in Texas, Oklahoma, and Kansas during the last 10 years has made the evaluation of the seismic hazard in these States increasingly pertinent. Such evaluation requires the development of ground motion prediction equations (GMPEs) that are tuned to the characteristics of the observed, and potentially induced, seism...

Tens of thousands of landslides were generated over 10, 000 km2 of North Canterbury and Marlborough as a consequence of the 14 November 2016, MW7.8 Kaikōura Earthquake. The most intense landslide damage was concentrated in 3500 km2 around the areas of fault rupture. Given the sparsely populated area affected by landslides, only a few homes were imp...

The P-wave seismogram method is used to develop estimates of the time averaged shear wave velocity of the upper 30 m (VS30) at 251 seismic stations in Texas, Oklahoma, and Kansas. Geologic conditions at the sites are documented using large-scale geologic maps. The VS30 values from the P-wave seismogram method agree well with the limited in situ mea...

Natural hazards engineering plays an important role in minimizing the effects of natural hazards on society through the design of resilient and sustainable infrastructure. The DesignSafe cyberinfrastructure has been developed to enable and facilitate transformative research in natural hazards engineering, which necessarily spans across multiple dis...

Time-averaged shear-wave velocity in the upper 30 m of a site (VS30) is the most common parameter used to characterize seismic site response in ground-motion models. However, in central and eastern North America (CENA), only 6% of the seismic recording stations that contributed data to the Next Generation Attenuation-East (NGA-East) project have me...

Seismic sliding block displacements provide a useful index for the seismic performance of a slope and are computed for a suite of acceleration-time histories selected to fit a target ground motion. This paper explores the effect of different ground motion selection techniques on computed rigid sliding block displacements. In particular, capturing t...

Geologic-Geomorphic map of Port-au-Prince, Haiti showing distribution of geologic units, faults, MASW measurement sites, and geomorphology used for analyses of building structural damage distribution and for building code seismic classification

A number of strategies exist to account for the epistemic uncertainty and aleatory variability in shear-wave velocity (Vs) profiles used in site response analyses. Epistemic uncertainty may be accounted for by using median and bounding-type profiles (e.g., ±20%), while aleatory variability may be accounted for by using Vs randomization procedures....

Uncertainty in site response analyses can be attributed to a number of parameters, including analysis methods, input ground motions, nonlinear dynamic soil properties, and shear-wave velocity profiles. In this paper, several approaches commonly used to account for shear-wave velocity (Vs) uncertainty in site response are investigated. Specifically,...

Studies have shown that random vibration theory (RVT) site-response analysis predicts site amplification at the natural site frequencies that are systematically larger than the results obtained from time series (TS) analysis using a suite of input TS. A critical part of the RVT approach is the peak factor, defined as the ratio of the peak to root m...

Nonlinear site response analyses are generally preferred over equivalent linear analyses for soft soil sites subjected to high-intensity input ground motions. However, both nonlinear (NL) and equivalent linear (EQL) analyses often result in large shear strain estimates (3-10%) at soft sites, and these large strains may generate unusual characterist...

Performance-based seismic design of important structures requires design ground motions from probabilistic seismic hazard analysis (PSHA) that incorporate the effects of local site conditions. Seismic hazard curves incorporating site-specific soil conditions can be generated through the convolution of rock hazard curves with statistical models for...

This study investigates the conditions for which one-dimensional (1D) nonlinear (NL) site response analysis results are distinct from equivalent-linear (EL) results and provides guidance for predicting when differences are large enough to be of practical significance. Relative differences in spectral accelerations and Fourier amplitudes computed fr...

Seismic landslide hazard maps are used in regional planning to identify zones that require detailed, site-specific studies. Most seismic landslide hazard maps are based on predicted sliding block displacements for a given level of shaking, but this deterministic approach does not fully consider the aleatory variability in the sliding displacement p...

Numerical techniques commonly used to compute the dynamic response of soil deposits under earthquake shaking are investigated by analyzing data from instrumented borehole arrays. Eleven instrumented vertical arrays are investigated using over 650 recorded ground motions that span a range of shaking intensities. Based on data from the selected boreh...

Probabilistic seismic hazard analysis (PSHA) is now the standard approach for developing earthquake ground motions for seismic design because it takes into account the important sources of uncertainty and variability associated with ground motion prediction. PSHA typically does not account for local site response but rather provides a uniform hazar...

The time-averaged shear (S) wave velocity in the upper 30 meters of sediment (VS30) is a widely used site parameter for ground motion prediction. When unavailable from measurements, as is often the case at accelerograph stations in Central and Eastern North America (CENA), VS30 is typically estimated from proxies. We propose an alternative for CENA...

Finite-element analyses are performed of centrifuge tests consisting of untreated and drain-treated lateral spread sites, with the goal of evaluating the ability of numerical simulations to predict the response of sites improved with prefabricated vertical drains. Finite-element models of varying complexity are analyzed: a two-dimensional model of...

Aleatory variability in ground-motion prediction, represented by the standard deviation (sigma) of a ground-motion prediction equation, exerts a very strong influence on the results of probabilistic seismic-hazard analysis (PSHA). This is especially so at the low annual exceedance frequencies considered for nuclear facilities; in these cases, even...

Sliding block displacements are used to evaluate the potential for seismic slope instability. Deterministic approaches are typically used to predict the expected level of sliding block displacement, although they do not rigorously account for uncertainties in the expected ground shaking, dynamic response, or displacement prediction. As a result, th...

The reference rock site condition has two important applications for ground‐motion prediction in the stable continental region of central and eastern North America (CENA). (1) It represents the site condition for which ground motions are computed using semiempirical ground‐motion prediction equations. In addition, (2) it represents the site conditi...

We appreciate the comments of Graizer (2013) and agree that the accuracy of all site‐response methods should be evaluated with respect to recordings from downhole array sites. However, the goal of our study was not to evaluate the absolute accuracy of a specific method of site‐response analysis, but rather to evaluate two approaches to the same met...

A probabilistic seismic hazard analysis has been conducted for a potential nuclear power plant site on the coast of South Africa, a country of low-to-moderate seismicity. The hazard study was conducted as a SSHAC Level 3 process, the first application of this approach outside North America. Extensive geological investigations identified five fault...

Earthquake-induced landslides are a significant seismic hazard that can generate large economic losses. Regional maps of seismic landslide potential are used in land-use planning and to identify zones that require detailed, site-specific studies. Current seismic landslide hazard mapping efforts typically utilize deterministic approaches to estimate...

The 2010-2011 New Zealand earthquakes induced significant liquefaction and associated lateral spreading displacements within the Canterbury Plains in and around the city of Christchurch. Massive amounts of soil ejecta and settlement of residential structures occurred in Christchurch and its eastern suburbs, with the most severe occurring along rive...

Regional seismic landslide hazard maps are based on predictions of rigid-sliding-block displacement derived from estimates of earthquake ground shaking, topography, geology, and shear strength. The confidence in these predictions requires comparisons with field observations of landslide occurrence during previous well-documented earthquakes. This p...

This paper describes the cyberinfrastructure (CI) of the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) and examines the evidence that this infrastructure is facilitating earthquake engineering research. Among the key features of the CI are the NEES Project Warehouse (PW), which is a data repository for earthquake enginee...

The random-vibration theory (RVT) approach to equivalent-linear site-response analysis is often used to simulate site amplification, particularly when large numbers of simulations are required for incorporation into probabilistic seismic-hazard analysis. The fact that RVT site-response analysis does not require the specification of input-time serie...

Earthquake-induced landslides are a significant seismic hazard that can generate significant economic losses. To gauge the potential for this hazard, regional seismic landslide maps are developed based on estimates of rigid sliding block displacement from empirical predictive models. Previous earthquakes with well-documented landslide inventories p...

Spaceborne remote sensing provides important field observations of landslide movements over spatial and temporal scales that cannot be simultaneously achieved with traditional field instrumentation. Analyses of multi temporal data from both radar and optical spaceborne systems have been successfully used in the past to identify and map landslides o...

The discrete nature of the numerical methods utilized in 1D site response analysis and calculation of the response spectra (e.g., frequency domain, Duhamel integral, and Newmark β methods) introduces time-step dependence in the resulting solution. Using an input ground motion with too large of a time-step leads to under-prediction of high-frequency...

Drainage methods for liquefaction remediation have been in use since the 1970s and have traditionally included stone columns, gravel drains, and more recently prefabricated vertical drains. This paper presents the results from a dynamic centrifuge test designed to evaluate the performance of a liquefiable site treated with prefabricated vertical dr...

Radar interferometry using Synthetic Aperture Radar (SAR) and the Persistent Scatterer approach (PS-InSAR) uses the differences in the phases of nearly-coincident SAR images collected at different times to measure the surface movements that occur along the radar line-of-sight (LOS). PS-InSAR analysis was applied to the Penitencia Creek landslide lo...

The George E. Brown Network for Earthquake Engineering Simulation (NEES), funded by the National Science Foundation, operates a shared national network of civil engineering experimental facilities that seeks to develop effective ways of mitigating earthquake damage through improved designs, materials, and construction techniques. Central to NEES is...