
R. R. YoungsAMEC · Environment & Infrastructure
R. R. Youngs
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37
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Introduction
Skills and Expertise
Publications
Publications (37)
The NGA-West2 project is a large multidisciplinary, multi-year research program on the Next Generation Attenuation (NGA) models for shallow crustal earthquakes in active tectonic regions. The research project has been coordinated by the Pacific Earthquake Engineering Research Center (PEER), with extensive technical interactions among many individua...
A presentation of the model parameters and comparison of the median ground-motion values from the NGA-West2 GMPEs is presented for a suite of deterministic cases. In general, the median ground motions are similar, within a factor of about 1.5-2.0 for 5 < M < 7 and distances between 10-100 km Differences increase (on the order of 2-3) for large-magn...
As part of the BC Hydro Probabilistic Seismic Hazard Analysis Model Project, we have developed a new seismic source model of the Cascadia subduction zone (CSZ) using a logic tree approach. The five most significant CSZ seismic source parameters to hazard in the Pacific Northwest are: segmentation, the location of the eastern edge of the megathrust...
This paper presents the development of a ground-motion prediction model for small-to-moderate shallow crustal earthquakes (3 <= M <= 5.5, up to 200 km distance) using data from the California ShakeMap systems. Our goal is to provide an empirical model that can be confidently used in the investigation of ground-motion difference between California a...
Under the direction of National Cooperative for the Disposal of Radioactive Waste (NAGRA), a probabilistic seismic hazard
analysis was conducted for the Swiss nuclear power plant sites. The study has become known under the name “PEGASOS Project.”
This is the first of a group of papers in this volume that describes the seismic source characterizatio...
Quantification of uncertainties is an essential component of probabilistic seismic and volcanic hazard assessments. Formal expert assessment is a structured and documented process for identifying and quantifying uncertainties. Expert judgment is used in any technical assessment, but often is implicit and undocumented. Formal expert assessment expli...
The effects of earthquakes may be the most significant natural hazard that can impact the Delta levees, whose potential failure would be catastrophic to California's economy. A probabilistic seismic hazard analysis (PSHA) was performed to characterize the ground shaking hazard that could contribute to levee failure in the Delta. Based on a seismic...
We present a model for estimating horizontal ground motion amplitudes caused by shallow crustal earthquakes occurring in active tectonic environments. The model provides predictive relationships for the orientation-independent average horizontal component of ground motions. Relationships are provided for peak acceleration, peak velocity, and 5-perc...
The data sets, model parameterizations, and results from the five NGA models for shallow crustal earthquakes in active tectonic regions are compared. A key difference in the data sets is the inclusion or exclusion of aftershocks. A comparison of the median spectral values for strike-slip earthquakes shows that they are within a factor of 1.5 for ma...
Yucca Mountain, Nevada has been recommended and approved for development as the site of the United States' first permanent repository for the disposal of spent nuclear fuel and high-level radioactive waste. As part of the development process, a license application has been prepared and submitted to the U.S. Nuclear Regulatory Commission. The licens...
Probabilistic seismic hazard analyses provide the opportunity, indeed the requirement, to quantify the uncertainties in important inputs to the analysis. The locations of future earthquakes, their recurrence rates and maximum size, and the ground motions that will result at a site of interest are all quantities that require careful consideration be...
The U.S. Department of Energy (DOE) considers volcanism to be a potentially disruptive class of events that could affect the safety of the proposed high-level waste repository at Yucca Mountain. Volcanic hazard assessment in monogenetic volcanic fields depends on an adequate understanding of the temporal and spatial pattern of past eruptions. At Yu...
A probabilistic volcanic hazard analysis (PVHA) was conducted in 1996 for the proposed repository at Yucca Mountain, Nevada. Based on data gathered by the Yucca Mountain Project over the course of about 15 years, the analysis integrated the judgments of a panel of ten volcanic experts using methods of formal expert elicitation. PVHA resulted in a p...
Probabilistic hazard analyses, which have been successfully used to evaluate various geohazards in both onshore and offshore environments, provide results that feed directly into project risk analyses. Evolving regulatory environments likely will incorporate more probabilistic and risk-based analyses in the future and this paper describes some of t...
We present a methodology for conducting a site-specific probabilistic analysis
of fault displacement hazard. Two approaches are outlined. The first relates the
occurrence of fault displacement at or near the ground surface to the occurrence
of earthquakes in the same manner as is done in a standard probabilistic seismic
hazard analysis (PSHA) for g...
Seafloor faults having strong geomorphic expression and evidence for late Quaternary activity (i.e. < 150,000 years) are common geologic features associated with the Sigsbee Escarpment. Waterbottom maps derived from exploration 3D multichannel seismic data provided an early indication that several zones of seafloor faults are in the vicinity of the...
Abstract The number,of strong ground motion recordings available for regression analysis in developing empirical attenuation relationships has rapidly grown,in the last 10 years. However, the dearth of strong-motion data from the Cascadia subduc- tion zone has limited this development,of relationships for the Cascadia subduction zone megathrust, wh...
Probabilistic seismic hazard analyses were conducted to estimate both ground motion and fault displacement hazards at the potential geologic repository for spent nuclear fuel and high-level radioactive waste at Yucca Mountain, Nevada. The study is believed to be the largest and most comprehensive analyses ever conducted for ground-shaking hazard an...
This paper presents a probabilistic assessment of the ground-shaking hazard along the Wasatch Front urban corridor, utilizing the extensive geological and seismological data base that has been developed for the region. Using a logic tree methodology, the approach formally incorporates uncertainty in earthquake source geometry and fault segmentation...
We present a summary of the methodology for probabilistic fault displacement hazard and discuss the types of data needed for the analysis. The methodology is based on the widely used formulation for probabilistic assessment of ground shaking hazard. We distinguish between principal faulting, ruptures occurring on the fault producing the earthquake,...
We present attenuation relationships for peak ground acceleration and response spectral acceleration for subduction zone interface
and intraslab earthquakes of moment magnitude M 5 and greater and for distances of 10 to 500 km. The relationships were developed by regression analysis using a random effects
regression model that addresses criticism o...
Attenuation relationships are presented for peak acceleration and response spectral accelerations from shallow crustal earthquakes.
The relationships are based on strong motion data primarily from California earthquakes. Relationships are presented for strike-slip
and reverse-faulting earthquakes, rock and deep firm soil deposits, earthquakes of mo...
The paper examines the variability of peak horizontal and vertical accelerations of the large California strong-motion data set for the time period 1957 to 1991 and find a statistically significant dependence of the standard error on earthquake magnitude. Specifically, the standard error decreases with increasing magnitude. The analysis was conduct...
This report summarizes the results of the Earthquakes and Tectonics Expert Judgement Excitation Project sponsored by the Electric Power Research Institute (EPRI). The objectives of this study were two-fold: (1) to demonstrate methods for the excitation of expert judgement, and (2) to quantify the uncertainties associated with earthquake and tectoni...
This study develops a methodology for making decisions involving complex earth science systems and demonstrates its feasibility in relation to issues of radioactive waste storage at Yucca Mountain, Nevada. The basic approach involves a team of experts working together to identify and evaluate the key events, processes and parameters that are critic...
Ground motion assessments are presented for evaluation of the seismic safety of K-Reactor at the Savannah River Site. Two earthquake sources are identified as the most significant to seismic hazard at the site, a M 7.5 earthquake occurring in Charleston, South Carolina, and a M 5 event occurring in the site vicinity. These events control the low fr...
A key assumption in standard probabilistic seismic hazard analysis (PSHA) is that earthquake occurrence can be modeled as a Poisson process (time-independent). For but a few regions in the world, however, the timing information on past earthquakes are not sufficient to calculate time-dependent hazard. We have calculated time-dependent probabilistic...
San Jose, California is located within a region of high seismic potential. This study assesses liquefaction potential within San Jose by evaluating liquefaction susceptibility, liquefaction opportunity, and probability of liquefaction. Liquefaction susceptibility was evaluated principally by mapping the Quaternary geologic deposits in the City, and...
The occurrence of the damaging 1983 M[sub w] 6.8 Borah Peak, Idaho earthquake, which ruptured a central segment of the Lost River fault, has increased the awareness of seismic hazards in this portion of the Northern Basin and Range Province (NBR). As a result, comprehensive deterministic and probabilistic seismic hazard analyses were performed for...