Research geophysicist with the U.S. Geological Survey studying various aspects of seismic hazard including ground motions and earthquake probabilities
I began with the National Seismic Hazards Modeling Project in Golden, CO in 2004 studying time-dependent seismic hazard in Alaska and producing a seismic hazard analysis of Afghanistan, the latter being done in conjunction with other U.S. Agency for International Development’s reconstruction efforts in Afghanistan. I moved to Memphis, TN in 2007 to focus on earthquake hazards in the central and eastern United States (CEUS) and returned to Golden in 2013 to work on issues related to earthquake hazards across the conterminous United States, specifically those related to earthquake ground motions as part of the Ground Motion Project. Much of my past research has centered on several aspects of earthquake hazards including time-dependent earthquake probabilities, declustering of foreshocks and aftershocks, and parameters related to earthquake sources. I helped update the CEUS source models for the 2008 and 2014 updates of the National Seismic Hazard Model (NSHM) and helped to incorporate basin models in the western United States for the 2018 update of the NSHM. More recently, I have been helping to contruct a geology-based National Crustal Model for earthquake hazard studies. Prior to joining the Survey, I obtained my Ph.D. in Geophysics from the University of Colorado at Boulder where I performed laboratory experiments of seismic wave attenuation in artificial glass cracks and glass bead cylinders, produced and interpreted tomographic models of seismic wave attenuation and velocity beneath the western United States, and studied receiver functions in New Zealand.
Science and Products
Database of Central and Eastern North American Seismic Velocity Structure
The "Database of Central and Eastern North American Seismic Velocity Structure" involves the compilation of one-dimensional (1D) seismic velocity-depth functions for central and eastern North America (CENA). The present database is an update of the report by Chulick and Mooney (2002) who present a compilation and statistical analysis of 1D seismic velocity-depth functions for North Ameri
Database for the Central United States Velocity Model, v1.3
We have developed a new three-dimensional seismic velocity model of the central United States (CUSVM) that includes the New Madrid Seismic Zone (NMSZ) and covers parts of Arkansas, Mississippi, Alabama, Illinois, Missouri, Kentucky, and Tennessee. The model represents a compilation of decades of crustal research consisting of seismic, aeromagnetic, and gravity profiles; geologic mapping; geophysic
Ground motion Fourier and response spectra from Utah earthquakes, 2010--2020
Records from strong motion stations were downloaded from FDSN and CESMD data centers with a search radius of approximately 220 km from Salt Lake City. Waveforms were processed to deconvolve instrument response and for baseline corrections. Signal was separated from noise using an automated P-wave picker. The signal was then windowed to include the mean plus two standard deviations of the signal. A
Digitized datasets of the structure of Cenozoic and late Cretaceous strata along the Atlantic and Gulf Coastal Plains from Texas to New Jersey
This dataset consists of shapefiles that are digitized contours of the structure of Cenozoic and late Cretaceous strata along the Gulf and Atlantic Coastal plains from Texas to New Jersey, not including Maryland and Delaware. Well depths and seismic profiles indicating depth to or elevation of subsurface geologic contacts present in some datasets have also been digitized. Metadata files (.xml) des
Calibration Coefficients for the U.S. Geological Survey National Crustal Model and Depth to Water Table
The U.S. Geological Survey National Crustal Model (NCM) is being developed to include spatially varying estimates of site response in seismic hazard assessments. Primary outputs of the NCM are continuous velocity and density profiles from the Earth's surface to the mantle transition zone at 410 km depth for each location on a 1-kilometer grid across the conterminous United States. Datasets used to
3D Geologic Framework for use with the U.S. Geological Survey National Crustal Model, Phase 1: Western United States
A 3D geologic framework is presented here as part of the U.S. Geological Survey National Crustal Model for the western United States, which will be used to improve seismic hazard assessment. The framework is based on 1:250,000 to 1:1,000,000-scale state geologic maps and depths of multiple subsurface unit boundaries. The geology at or near the Earth’s surface is based on published maps with modifi
Grids in support of the U.S. Geological Survey Thermal Model for Seismic Hazard Studies
A 3D temperature model is constructed in order to support the estimation of physical parameters within the USGS National Crustal Model. The crustal model is defined by a geological framework consisting of various lithologies with distinct mineral compositions. A temperature model is needed to calculate mineral density and bulk and shear modulus as a function of position within the crust. These pro
An updated stress map of the continental U.S. reveals heterogeneous intraplate stress
Earthquake focal mechanisms and stress inversion results for the conterminous United States.
Petrologic and Mineral Physics Database for use with the USGS National Crustal Model - Data Release
We present a petrologic and mineral physics database as part of the USGS National Crustal Model (NCM) for the western United States. Each of 209 geologic units, 134 of which are currently part of the geologic framework within the NCM, is assigned a mineralogical composition according to generalized classifications with some refinement for specific geologic formations. The mineral physics database
Thickness of unconsolidated sediments for the USGS National Crustal Model
We present a numeric grid containing estimates of the thickness of unconsolidated sediments for the western United States. Values for these grids were combined and integrated from previous studies or derived directly from gravity analyses. The grids are provided with 1-km grid-node spacing in WGS84 latitude-longitude coordinates. Detailed information regarding the derivation of these estimates is
Depth to Mesozoic basement for the USGS National Crustal Model
We present a numeric grid containing estimates of the depth to the pre-Cenozoic basement for the western United States. Values for these grids were combined and integrated from previous studies or derived directly from gravity analyses. The grids are provided with 1-km grid-node spacing in WGS84 latitude-longitude coordinates. Detailed information regarding the derivation of these estimates is pro
Filter Total Items: 42
Crustal seismic attenuation of the central United States and Intermountain West
Seismic attenuation is generally greater in the western United States (WUS) than the central and eastern United States (CEUS), but the nature of this transition or location of this boundary is poorly constrained. We conduct crustal seismic (Lg) attenuation tomography across a region that stretches from the CEUS across the Rocky Mountains to the Basin and Range using a total of 115,870 amplitude me
Seismic wave propagation and basin amplification in the Wasatch Front, Utah
Ground‐motion analysis of more than 3000 records from 59 earthquakes, including records from the March 2020 Mw 5.7 Magna earthquake sequence, was carried out to investigate site response and basin amplification in the Wasatch Front, Utah. We compare ground motions with the Bayless and Abrahamson (2019; hereafter, BA18) ground‐motion model (GMM) for Fourier amplitude spectra, which was developed on
The 2018 update of the US National Seismic Hazard Model: Where, why, and how much probabilistic ground motion maps changed
The 2018 US Geological Survey National Seismic Hazard Model (NSHM) incorporates new data and updated science to improve the underlying earthquake and ground motion forecasts for the conterminous United States. The NSHM considers many new data and component input models: (1) new earthquakes between 2013 and 2017 and updated earthquake magnitudes for some earlier earthquakes; (2) two updated smoothe
Calibration of the U.S. Geological Survey National Crustal Model
The U.S. Geological Survey National Crustal Model (NCM) is being developed to include spatially varying estimates of site response in seismic hazard assessments. Primary outputs of the NCM are continuous velocity and density profiles from the Earth’s surface to the mantle transition zone at 410-kilometer (km) depth for each location on a 1-km grid across the conterminous United States. Datasets us
Temperature model in support of the U.S. Geological Survey National Crustal Model for seismic hazard Ssudies
The U.S. Geological Survey National Crustal Model (NCM) is being developed to assist with earthquake hazard and risk assessment by supporting estimates of ground shaking in response to an earthquake. The period-dependent intensity and duration of shaking depend upon the three-dimensional seismic velocity, seismic attenuation, and density distribution of a region, which in turn is governed to a lar
The 2018 update of the US National Seismic Hazard Model: Overview of model and implications
During 2017–2018, the National Seismic Hazard Model for the conterminous United States was updated as follows: (1) an updated seismicity catalog was incorporated, which includes new earthquakes that occurred from 2013 to 2017; (2) in the central and eastern United States (CEUS), new ground motion models were updated that incorporate updated median estimates, modified assessments of the associated
3D geologic framework for use with the U.S. Geological Survey National Crustal Model, Phase 1—Western United States
A 3D geologic framework is presented here as part of the U.S. Geological Survey National Crustal Model for the western United States, which will be used to improve seismic hazard assessment. The framework is based on 1:250,000 to 1:1,000,000-scale state geologic maps and depths of multiple subsurface unit boundaries. The geology at or near the Earth’s surface is based on published maps with modifi
Status of three-dimensional geological mapping and modeling activities in the U.S. Geological Survey
The U.S. Geological Survey (USGS), created in 1879, is the national geological survey
for the United States and the sole science agency within its cabinet-level bureau, the
Department of the Interior. The USGS has a broad mission, including: serving the Nation by
providing reliable scientific information to describe and understand the Earth; minimize loss of
life and property from natural disaster
Documentation for the 2008 update of the United States National Seismic Hazard Maps
The 2008 U.S. Geological Survey (USGS) National Seismic Hazard Maps display earthquake ground motions for various probability levels across the United States and are applied in seismic provisions of building codes, insurance rate structures, risk assessments, and other public policy. This update of the maps incorporates new findings on earthquake ground shaking, faults, seismicity, and geodesy. Th
Petrologic and mineral physics database for use with the U.S. Geological Survey National Crustal Model
We present a petrologic and mineral physics database as part of the U.S. Geological Survey National Crustal Model (NCM). Each of 209 geologic units, 134 of which are currently part of the geologic framework within the NCM, was assigned a mineralogical composition according to generalized classifications with some refinement for specific geologic formations. This report is concerned with the petrol
The USGS National crustal model for seismic hazard studies: 2019 update
The United States Geological Survey (USGS) National Crustal Model (NCM) is being developed to assist in the modeling of seismic hazards across the conterminous United States, specifically by improving estimates of site response. The NCM is composed of geophysical profiles, extending from the Earth’s surface into the upper mantle, constructed from 5 primary elements: 1) depth to bedrock and basemen
Code to access the Central United States Velocity Model, v1.3
We have developed a new three-dimensional seismic velocity model of the central United States (CUSVM) that includes the New Madrid Seismic Zone (NMSZ) and covers parts of Arkansas, Mississippi, Alabama, Illinois, Missouri, Kentucky, and Tennessee (Ramirez Guzman et al, 2012). The model represents a compilation of decades of crustal research consisting of seismic, aeromagnetic, and gravity profiles
GeoPhys
This set of utilities is used to extract geophysical information from the NCM (Boyd, 2020) including, for example, S-wave, P-wave, and density profiles, as well as attributes for ground motions models including VS30, Z1.0, and Z2.5. Running the code in either MATLAB or Python requires all of the NCM databases (https://doi.org/10.5066/P9T96Q67).
TherMod
This set of utilities is used to extract temperature profiles and maps from the NCM thermal model (Boyd, 2019). Running the code requires the NCM thermal model, NCM_TemperatureGrids.nc (https://doi.org/10.5066/P935DT1G), and the NCM spatial grid, NCM_SpatialGrid.nc (https://doi.org/10.5066/P9SBQENM). These codes and datasets are part of an effort to produce a three dimensional national crustal mod
GeoFram
This set of utilities is used to extract geologic profiles from the NCM geologic framework (Boyd, 2019). Running the code in either MATLAB or Python requires the NCM geologic framework and related databases, NCM_GeologicFrameworkVolume.nc, NCM_GeologicFrameworkGrids.nc, and NCM_SpatialGrid.nc (https://doi.org/10.5066/P9SBQENM). These data and codes are part of an effort to produce a three dimensio
MinVel
This program is used to calculate anharmonic p- and s-wave velocity and density for zero-porosity mineral aggregates. It is based on the work of Hacker and Abers (2004, updated in 2016) with additional minerals and optimized for related work. Running the code in either MATLAB or Python requires a mineral physics database, MineralPhysicsDatabase.nc (https://doi.org/10.5066/P9HN170G). Combined with
Science and Products
- Data
Database of Central and Eastern North American Seismic Velocity Structure
The "Database of Central and Eastern North American Seismic Velocity Structure" involves the compilation of one-dimensional (1D) seismic velocity-depth functions for central and eastern North America (CENA). The present database is an update of the report by Chulick and Mooney (2002) who present a compilation and statistical analysis of 1D seismic velocity-depth functions for North AmeriDatabase for the Central United States Velocity Model, v1.3
We have developed a new three-dimensional seismic velocity model of the central United States (CUSVM) that includes the New Madrid Seismic Zone (NMSZ) and covers parts of Arkansas, Mississippi, Alabama, Illinois, Missouri, Kentucky, and Tennessee. The model represents a compilation of decades of crustal research consisting of seismic, aeromagnetic, and gravity profiles; geologic mapping; geophysicGround motion Fourier and response spectra from Utah earthquakes, 2010--2020
Records from strong motion stations were downloaded from FDSN and CESMD data centers with a search radius of approximately 220 km from Salt Lake City. Waveforms were processed to deconvolve instrument response and for baseline corrections. Signal was separated from noise using an automated P-wave picker. The signal was then windowed to include the mean plus two standard deviations of the signal. ADigitized datasets of the structure of Cenozoic and late Cretaceous strata along the Atlantic and Gulf Coastal Plains from Texas to New Jersey
This dataset consists of shapefiles that are digitized contours of the structure of Cenozoic and late Cretaceous strata along the Gulf and Atlantic Coastal plains from Texas to New Jersey, not including Maryland and Delaware. Well depths and seismic profiles indicating depth to or elevation of subsurface geologic contacts present in some datasets have also been digitized. Metadata files (.xml) desCalibration Coefficients for the U.S. Geological Survey National Crustal Model and Depth to Water Table
The U.S. Geological Survey National Crustal Model (NCM) is being developed to include spatially varying estimates of site response in seismic hazard assessments. Primary outputs of the NCM are continuous velocity and density profiles from the Earth's surface to the mantle transition zone at 410 km depth for each location on a 1-kilometer grid across the conterminous United States. Datasets used to3D Geologic Framework for use with the U.S. Geological Survey National Crustal Model, Phase 1: Western United States
A 3D geologic framework is presented here as part of the U.S. Geological Survey National Crustal Model for the western United States, which will be used to improve seismic hazard assessment. The framework is based on 1:250,000 to 1:1,000,000-scale state geologic maps and depths of multiple subsurface unit boundaries. The geology at or near the Earth’s surface is based on published maps with modifiGrids in support of the U.S. Geological Survey Thermal Model for Seismic Hazard Studies
A 3D temperature model is constructed in order to support the estimation of physical parameters within the USGS National Crustal Model. The crustal model is defined by a geological framework consisting of various lithologies with distinct mineral compositions. A temperature model is needed to calculate mineral density and bulk and shear modulus as a function of position within the crust. These proAn updated stress map of the continental U.S. reveals heterogeneous intraplate stress
Earthquake focal mechanisms and stress inversion results for the conterminous United States.Petrologic and Mineral Physics Database for use with the USGS National Crustal Model - Data Release
We present a petrologic and mineral physics database as part of the USGS National Crustal Model (NCM) for the western United States. Each of 209 geologic units, 134 of which are currently part of the geologic framework within the NCM, is assigned a mineralogical composition according to generalized classifications with some refinement for specific geologic formations. The mineral physics databaseThickness of unconsolidated sediments for the USGS National Crustal Model
We present a numeric grid containing estimates of the thickness of unconsolidated sediments for the western United States. Values for these grids were combined and integrated from previous studies or derived directly from gravity analyses. The grids are provided with 1-km grid-node spacing in WGS84 latitude-longitude coordinates. Detailed information regarding the derivation of these estimates isDepth to Mesozoic basement for the USGS National Crustal Model
We present a numeric grid containing estimates of the depth to the pre-Cenozoic basement for the western United States. Values for these grids were combined and integrated from previous studies or derived directly from gravity analyses. The grids are provided with 1-km grid-node spacing in WGS84 latitude-longitude coordinates. Detailed information regarding the derivation of these estimates is pro - Publications
Filter Total Items: 42
Crustal seismic attenuation of the central United States and Intermountain West
Seismic attenuation is generally greater in the western United States (WUS) than the central and eastern United States (CEUS), but the nature of this transition or location of this boundary is poorly constrained. We conduct crustal seismic (Lg) attenuation tomography across a region that stretches from the CEUS across the Rocky Mountains to the Basin and Range using a total of 115,870 amplitude meSeismic wave propagation and basin amplification in the Wasatch Front, Utah
Ground‐motion analysis of more than 3000 records from 59 earthquakes, including records from the March 2020 Mw 5.7 Magna earthquake sequence, was carried out to investigate site response and basin amplification in the Wasatch Front, Utah. We compare ground motions with the Bayless and Abrahamson (2019; hereafter, BA18) ground‐motion model (GMM) for Fourier amplitude spectra, which was developed onThe 2018 update of the US National Seismic Hazard Model: Where, why, and how much probabilistic ground motion maps changed
The 2018 US Geological Survey National Seismic Hazard Model (NSHM) incorporates new data and updated science to improve the underlying earthquake and ground motion forecasts for the conterminous United States. The NSHM considers many new data and component input models: (1) new earthquakes between 2013 and 2017 and updated earthquake magnitudes for some earlier earthquakes; (2) two updated smootheCalibration of the U.S. Geological Survey National Crustal Model
The U.S. Geological Survey National Crustal Model (NCM) is being developed to include spatially varying estimates of site response in seismic hazard assessments. Primary outputs of the NCM are continuous velocity and density profiles from the Earth’s surface to the mantle transition zone at 410-kilometer (km) depth for each location on a 1-km grid across the conterminous United States. Datasets usTemperature model in support of the U.S. Geological Survey National Crustal Model for seismic hazard Ssudies
The U.S. Geological Survey National Crustal Model (NCM) is being developed to assist with earthquake hazard and risk assessment by supporting estimates of ground shaking in response to an earthquake. The period-dependent intensity and duration of shaking depend upon the three-dimensional seismic velocity, seismic attenuation, and density distribution of a region, which in turn is governed to a larThe 2018 update of the US National Seismic Hazard Model: Overview of model and implications
During 2017–2018, the National Seismic Hazard Model for the conterminous United States was updated as follows: (1) an updated seismicity catalog was incorporated, which includes new earthquakes that occurred from 2013 to 2017; (2) in the central and eastern United States (CEUS), new ground motion models were updated that incorporate updated median estimates, modified assessments of the associated3D geologic framework for use with the U.S. Geological Survey National Crustal Model, Phase 1—Western United States
A 3D geologic framework is presented here as part of the U.S. Geological Survey National Crustal Model for the western United States, which will be used to improve seismic hazard assessment. The framework is based on 1:250,000 to 1:1,000,000-scale state geologic maps and depths of multiple subsurface unit boundaries. The geology at or near the Earth’s surface is based on published maps with modifiStatus of three-dimensional geological mapping and modeling activities in the U.S. Geological Survey
The U.S. Geological Survey (USGS), created in 1879, is the national geological survey for the United States and the sole science agency within its cabinet-level bureau, the Department of the Interior. The USGS has a broad mission, including: serving the Nation by providing reliable scientific information to describe and understand the Earth; minimize loss of life and property from natural disasterDocumentation for the 2008 update of the United States National Seismic Hazard Maps
The 2008 U.S. Geological Survey (USGS) National Seismic Hazard Maps display earthquake ground motions for various probability levels across the United States and are applied in seismic provisions of building codes, insurance rate structures, risk assessments, and other public policy. This update of the maps incorporates new findings on earthquake ground shaking, faults, seismicity, and geodesy. ThPetrologic and mineral physics database for use with the U.S. Geological Survey National Crustal Model
We present a petrologic and mineral physics database as part of the U.S. Geological Survey National Crustal Model (NCM). Each of 209 geologic units, 134 of which are currently part of the geologic framework within the NCM, was assigned a mineralogical composition according to generalized classifications with some refinement for specific geologic formations. This report is concerned with the petrolThe USGS National crustal model for seismic hazard studies: 2019 update
The United States Geological Survey (USGS) National Crustal Model (NCM) is being developed to assist in the modeling of seismic hazards across the conterminous United States, specifically by improving estimates of site response. The NCM is composed of geophysical profiles, extending from the Earth’s surface into the upper mantle, constructed from 5 primary elements: 1) depth to bedrock and basemen - Software
Code to access the Central United States Velocity Model, v1.3
We have developed a new three-dimensional seismic velocity model of the central United States (CUSVM) that includes the New Madrid Seismic Zone (NMSZ) and covers parts of Arkansas, Mississippi, Alabama, Illinois, Missouri, Kentucky, and Tennessee (Ramirez Guzman et al, 2012). The model represents a compilation of decades of crustal research consisting of seismic, aeromagnetic, and gravity profilesGeoPhys
This set of utilities is used to extract geophysical information from the NCM (Boyd, 2020) including, for example, S-wave, P-wave, and density profiles, as well as attributes for ground motions models including VS30, Z1.0, and Z2.5. Running the code in either MATLAB or Python requires all of the NCM databases (https://doi.org/10.5066/P9T96Q67).TherMod
This set of utilities is used to extract temperature profiles and maps from the NCM thermal model (Boyd, 2019). Running the code requires the NCM thermal model, NCM_TemperatureGrids.nc (https://doi.org/10.5066/P935DT1G), and the NCM spatial grid, NCM_SpatialGrid.nc (https://doi.org/10.5066/P9SBQENM). These codes and datasets are part of an effort to produce a three dimensional national crustal modGeoFram
This set of utilities is used to extract geologic profiles from the NCM geologic framework (Boyd, 2019). Running the code in either MATLAB or Python requires the NCM geologic framework and related databases, NCM_GeologicFrameworkVolume.nc, NCM_GeologicFrameworkGrids.nc, and NCM_SpatialGrid.nc (https://doi.org/10.5066/P9SBQENM). These data and codes are part of an effort to produce a three dimensioMinVel
This program is used to calculate anharmonic p- and s-wave velocity and density for zero-porosity mineral aggregates. It is based on the work of Hacker and Abers (2004, updated in 2016) with additional minerals and optimized for related work. Running the code in either MATLAB or Python requires a mineral physics database, MineralPhysicsDatabase.nc (https://doi.org/10.5066/P9HN170G). Combined with