Brad Aagaard
Brad Aagaard is a research scientist in the Earthquake Hazards Program.
Ground-motion modeling
- Animations of ground shaking from computer simulations of earthquakes.
- 3D Geologic and Seismic Velocity Model of the San Francisco Bay Region
Software
PyLith crustal deformation modeling software, Computational Infrastructure for Geodynamics.
Professional Experience
Research Geophysicist, USGS, 2003-present
USGS Mendenhall Postdoctoral Scholar, 2001-2003
Education and Certifications
Ph.D., Civil Engineering, California Institute of Technology, 2000
M.S., Civil Engineering, California Institute of Technology, 1995
B.S., Engineering, Harvey Mudd College, 1994
Science and Products
Crustal Characterization
The geophysical structure of the Earth’s crust, from the surface to the Moho, plays a major role in seismic hazard by influencing earthquake source properties and wave propagation from the earthquake to the Earth’s surface. We make field measurements and create models to better characterize the crust and resulting earthquake ground motions.
Ground-motion records and site information for Puerto Rico and the US Virgin Islands, 2006-2024 Ground-motion records and site information for Puerto Rico and the US Virgin Islands, 2006-2024
This dataset includes processed ground-motion records and horizontal pseudospectral accelerations (5-percent-damped) from magnitude 4.0-6.4 earthquakes occurring near Puerto Rico between 2006 and 2024. The dataset includes 10,127 records from 849 earthquakes and 71 stations passing automated and manual review. Spectral values are provided at 21 periods (0.01-10 s). It also includes site
Ground-motion records and basin depth models for Portland, Oregon, 2005-2022 Ground-motion records and basin depth models for Portland, Oregon, 2005-2022
This dataset includes processed ground-motion records and horizontal pseudospectral accelerations (5-percent-damped) from magnitude 3.0-6.8 earthquakes occurring in the vicinity of Portland, Oregon, between 2005 and 2022. The dataset includes 347 records from 134 earthquakes and 69 stations. Spectral values are provided at 21 periods (0.01-10 s). It also includes the basin depth models...
Ground-motion records and basin depth models for Reno, Nevada, 2008-2022 Ground-motion records and basin depth models for Reno, Nevada, 2008-2022
This dataset includes processed ground-motion records and horizontal pseudospectral accelerations (5-percent-damped) from magnitude 3.0-6.0 earthquakes occurring in the vicinity of Reno, Nevada, between 2008 and 2022. The dataset includes 592 records from 104 earthquakes and 42 stations. Spectral values are provided at 21 periods (0.01-10 s). Local basin depths as given by Z1.0 and Z2.5...
Ground-motion records and basin depth models for the Great Valley, California, 2000-2022 Ground-motion records and basin depth models for the Great Valley, California, 2000-2022
This dataset includes processed ground-motion records and horizontal pseudospectral accelerations (5-percent-damped) from magnitude 3.5-7.1 earthquakes occurring in the vicinity of the Great Valley, California, between 2000 and 2022. The dataset includes 12,044 records from 564 earthquakes and 254 stations. Spectral values are provided at 21 periods (0.01-10 s). It also includes the...
Data Release for the 2023 U.S. 50-State National Seismic Hazard Model - Overview Data Release for the 2023 U.S. 50-State National Seismic Hazard Model - Overview
This data release contains data sets associated with the 2023 50-State National Seismic Hazard Model Update. The 2023 50-State National Seimsic Hazard Model (NSHM) Update includes an update to the NSHMs for the conterminous U.S (CONUS, last updated in 2018), Alaska (AK, last updated in 2007), and Hawaii (last updated in 2001). Data sets include inputs like seismicity catalogs used as...
San Francisco Bay region 3D seismic velocity model v21.0 San Francisco Bay region 3D seismic velocity model v21.0
This three-dimensional (3D) seismic velocity model includes a detailed domain covering the greater San Francisco Bay urban region and a regional domain at a coarser resolution covering a larger region. Version 21.0 is a re-release of v08.3.0 in a new storage scheme. The model was constructed by assigning elastic properties (density, Vp, Vs, Qp, and Qs) to grids of points based on the...
Filter Total Items: 50
A partially nonergodic ground-motion model for Fourier amplitude spectra for the San Francisco Bay area, California, USA A partially nonergodic ground-motion model for Fourier amplitude spectra for the San Francisco Bay area, California, USA
We develop a partially nonergodic ground-motion model (GMM) for Fourier amplitude spectra for the San Francisco Bay Area, California, USA, using the Bayless and Abrahamson (2019) GMM as a reference ergodic GMM and developing location-dependent adjustments to the predicted median and variance. We compile regional ground-motion data from moment magnitude (𝑀w) >3 earthquakes occurring...
Authors
Morgan P. Moschetti, Eric M. Thompson, Ryan Peterson, James Andrew Smith, Brad T. Aagaard
A journey to the center of the USGS National Strong-motion Project processing and beyond A journey to the center of the USGS National Strong-motion Project processing and beyond
The United States Geological Survey (USGS) National Strong Motion Project (NSMP) has the primary U.S. government responsibility to acquire, process, and disseminate significant strong-motion earthquake ground motion records measured at surficial free-field stations, structures (buildings, dams, and bridges, and geotechnical arrays to the earthquake engineering community. As a result of...
Authors
Lisa Sue Schleicher, Jamison Haase Steidl, Eric M. Thompson, Alan K. Yong, Jeff Brody, James Luke Blair, Mike Hearne, Brad T. Aagaard, Susan E. Hough, Han Shao, Garet Huddleston, Keira Heilpern, Kristin Marano, Gabe Ferragut, B. Worden, David J. Wald, Jason De Cristofaro, Adria Ruth McClain, B. Dunham, D. Nget, J. Aragon, J. Gomez, V. Amador, V. Carrasco Rodriquez, E. E. Luna, D. Cembalski, D. Childs, J. Smith, D. Croker, L. Gee
Automated, near real-time ground-motion processing at the U.S. Geological Survey Automated, near real-time ground-motion processing at the U.S. Geological Survey
We describe automated ground‐motion processing software named gmprocess that has been developed at the U.S. Geological Survey (USGS) in support of near‐real‐time earthquake hazard products. Because of the open‐source development process, this software has benefitted from the involvement and contributions of a broad community and has been used for a wider range of applications than was...
Authors
Eric M. Thompson, Mike Hearne, Brad T. Aagaard, J.M. Rekoske, Charles Worden, Morgan P. Moschetti, Heather Elizabeth Hunsinger, Gabe C. Ferragut, Grace Alexandra Parker, James Andrew Smith, Kyle Ken Smith, Albert R. Kottke
2024 Crustal Deformation Modeling Workshop report 2024 Crustal Deformation Modeling Workshop report
The 2024 Crustal Deformation Modeling Workshop was held June 10–14 at the Colorado School of Mines. The workshop included two days of tutorials on using PyLith for crustal deformation modeling, followed by three days of science talks and discussions. The workshop focused on four primary themes: ● Constraining long-term fault slip rates and their uncertainties using geodetic and geologic...
Authors
Brad T. Aagaard, Matthew Knepley, Eric Lindsey, Kathryn Z. Materna, Hilary R Martens, Charles Williams
Integration of rupture directivity models for the US National Seismic Hazard Model Integration of rupture directivity models for the US National Seismic Hazard Model
Several rupture directivity models (DMs) have been developed in recent years to describe the near-source spatial variations in ground motion amplitudes related to propagation of rupture along the fault. We recently organized an effort towards incorporating these directivity effects into the USGS National Seismic Hazard Model (NSHM), by first evaluating the community's work and potential...
Authors
Kyle Withers, Morgan P. Moschetti, Peter M. Powers, Mark D. Petersen, Robert Graves, Brad T. Aagaard, Annemarie S. Baltay Sundstrom, Nico Luco, Erin A. Wirth, Sanaz Rezaeian, Eric M. Thompson
Empirical ground-motion basin response in the California Great Valley, Reno, Nevada, and Portland, Oregon Empirical ground-motion basin response in the California Great Valley, Reno, Nevada, and Portland, Oregon
We assess how well the Next-Generation Attenuation-West 2 (NGA-West2) ground-motion models (GMMs), which are used in the US Geological Survey’s (USGS) National Seismic Hazard Model (NSHM) for crustal faults in the western United States, predict the observed basin response in the Great Valley of California, the Reno basin in Nevada, and Portland and Tualatin basins in Oregon. These GMMs...
Authors
Sean Kamran Ahdi, Brad T. Aagaard, Morgan P. Moschetti, Grace Alexandra Parker, Oliver S. Boyd, William J. Stephenson
USGS automated ground motion processing software USGS automated ground motion processing software
The goal of this project is to update, restructure, and consolidate existing USGS ground-motion processing software to incorporate recent advances from researchers at the USGS, PEER, and others. It will standardize tools for multiple USGS ground-motion products and enable scientists within the USGS and the external community to develop and expand ground-motion datasets used in many...
Science and Products
Crustal Characterization
The geophysical structure of the Earth’s crust, from the surface to the Moho, plays a major role in seismic hazard by influencing earthquake source properties and wave propagation from the earthquake to the Earth’s surface. We make field measurements and create models to better characterize the crust and resulting earthquake ground motions.
Ground-motion records and site information for Puerto Rico and the US Virgin Islands, 2006-2024 Ground-motion records and site information for Puerto Rico and the US Virgin Islands, 2006-2024
This dataset includes processed ground-motion records and horizontal pseudospectral accelerations (5-percent-damped) from magnitude 4.0-6.4 earthquakes occurring near Puerto Rico between 2006 and 2024. The dataset includes 10,127 records from 849 earthquakes and 71 stations passing automated and manual review. Spectral values are provided at 21 periods (0.01-10 s). It also includes site
Ground-motion records and basin depth models for Portland, Oregon, 2005-2022 Ground-motion records and basin depth models for Portland, Oregon, 2005-2022
This dataset includes processed ground-motion records and horizontal pseudospectral accelerations (5-percent-damped) from magnitude 3.0-6.8 earthquakes occurring in the vicinity of Portland, Oregon, between 2005 and 2022. The dataset includes 347 records from 134 earthquakes and 69 stations. Spectral values are provided at 21 periods (0.01-10 s). It also includes the basin depth models...
Ground-motion records and basin depth models for Reno, Nevada, 2008-2022 Ground-motion records and basin depth models for Reno, Nevada, 2008-2022
This dataset includes processed ground-motion records and horizontal pseudospectral accelerations (5-percent-damped) from magnitude 3.0-6.0 earthquakes occurring in the vicinity of Reno, Nevada, between 2008 and 2022. The dataset includes 592 records from 104 earthquakes and 42 stations. Spectral values are provided at 21 periods (0.01-10 s). Local basin depths as given by Z1.0 and Z2.5...
Ground-motion records and basin depth models for the Great Valley, California, 2000-2022 Ground-motion records and basin depth models for the Great Valley, California, 2000-2022
This dataset includes processed ground-motion records and horizontal pseudospectral accelerations (5-percent-damped) from magnitude 3.5-7.1 earthquakes occurring in the vicinity of the Great Valley, California, between 2000 and 2022. The dataset includes 12,044 records from 564 earthquakes and 254 stations. Spectral values are provided at 21 periods (0.01-10 s). It also includes the...
Data Release for the 2023 U.S. 50-State National Seismic Hazard Model - Overview Data Release for the 2023 U.S. 50-State National Seismic Hazard Model - Overview
This data release contains data sets associated with the 2023 50-State National Seismic Hazard Model Update. The 2023 50-State National Seimsic Hazard Model (NSHM) Update includes an update to the NSHMs for the conterminous U.S (CONUS, last updated in 2018), Alaska (AK, last updated in 2007), and Hawaii (last updated in 2001). Data sets include inputs like seismicity catalogs used as...
San Francisco Bay region 3D seismic velocity model v21.0 San Francisco Bay region 3D seismic velocity model v21.0
This three-dimensional (3D) seismic velocity model includes a detailed domain covering the greater San Francisco Bay urban region and a regional domain at a coarser resolution covering a larger region. Version 21.0 is a re-release of v08.3.0 in a new storage scheme. The model was constructed by assigning elastic properties (density, Vp, Vs, Qp, and Qs) to grids of points based on the...
Filter Total Items: 50
A partially nonergodic ground-motion model for Fourier amplitude spectra for the San Francisco Bay area, California, USA A partially nonergodic ground-motion model for Fourier amplitude spectra for the San Francisco Bay area, California, USA
We develop a partially nonergodic ground-motion model (GMM) for Fourier amplitude spectra for the San Francisco Bay Area, California, USA, using the Bayless and Abrahamson (2019) GMM as a reference ergodic GMM and developing location-dependent adjustments to the predicted median and variance. We compile regional ground-motion data from moment magnitude (𝑀w) >3 earthquakes occurring...
Authors
Morgan P. Moschetti, Eric M. Thompson, Ryan Peterson, James Andrew Smith, Brad T. Aagaard
A journey to the center of the USGS National Strong-motion Project processing and beyond A journey to the center of the USGS National Strong-motion Project processing and beyond
The United States Geological Survey (USGS) National Strong Motion Project (NSMP) has the primary U.S. government responsibility to acquire, process, and disseminate significant strong-motion earthquake ground motion records measured at surficial free-field stations, structures (buildings, dams, and bridges, and geotechnical arrays to the earthquake engineering community. As a result of...
Authors
Lisa Sue Schleicher, Jamison Haase Steidl, Eric M. Thompson, Alan K. Yong, Jeff Brody, James Luke Blair, Mike Hearne, Brad T. Aagaard, Susan E. Hough, Han Shao, Garet Huddleston, Keira Heilpern, Kristin Marano, Gabe Ferragut, B. Worden, David J. Wald, Jason De Cristofaro, Adria Ruth McClain, B. Dunham, D. Nget, J. Aragon, J. Gomez, V. Amador, V. Carrasco Rodriquez, E. E. Luna, D. Cembalski, D. Childs, J. Smith, D. Croker, L. Gee
Automated, near real-time ground-motion processing at the U.S. Geological Survey Automated, near real-time ground-motion processing at the U.S. Geological Survey
We describe automated ground‐motion processing software named gmprocess that has been developed at the U.S. Geological Survey (USGS) in support of near‐real‐time earthquake hazard products. Because of the open‐source development process, this software has benefitted from the involvement and contributions of a broad community and has been used for a wider range of applications than was...
Authors
Eric M. Thompson, Mike Hearne, Brad T. Aagaard, J.M. Rekoske, Charles Worden, Morgan P. Moschetti, Heather Elizabeth Hunsinger, Gabe C. Ferragut, Grace Alexandra Parker, James Andrew Smith, Kyle Ken Smith, Albert R. Kottke
2024 Crustal Deformation Modeling Workshop report 2024 Crustal Deformation Modeling Workshop report
The 2024 Crustal Deformation Modeling Workshop was held June 10–14 at the Colorado School of Mines. The workshop included two days of tutorials on using PyLith for crustal deformation modeling, followed by three days of science talks and discussions. The workshop focused on four primary themes: ● Constraining long-term fault slip rates and their uncertainties using geodetic and geologic...
Authors
Brad T. Aagaard, Matthew Knepley, Eric Lindsey, Kathryn Z. Materna, Hilary R Martens, Charles Williams
Integration of rupture directivity models for the US National Seismic Hazard Model Integration of rupture directivity models for the US National Seismic Hazard Model
Several rupture directivity models (DMs) have been developed in recent years to describe the near-source spatial variations in ground motion amplitudes related to propagation of rupture along the fault. We recently organized an effort towards incorporating these directivity effects into the USGS National Seismic Hazard Model (NSHM), by first evaluating the community's work and potential...
Authors
Kyle Withers, Morgan P. Moschetti, Peter M. Powers, Mark D. Petersen, Robert Graves, Brad T. Aagaard, Annemarie S. Baltay Sundstrom, Nico Luco, Erin A. Wirth, Sanaz Rezaeian, Eric M. Thompson
Empirical ground-motion basin response in the California Great Valley, Reno, Nevada, and Portland, Oregon Empirical ground-motion basin response in the California Great Valley, Reno, Nevada, and Portland, Oregon
We assess how well the Next-Generation Attenuation-West 2 (NGA-West2) ground-motion models (GMMs), which are used in the US Geological Survey’s (USGS) National Seismic Hazard Model (NSHM) for crustal faults in the western United States, predict the observed basin response in the Great Valley of California, the Reno basin in Nevada, and Portland and Tualatin basins in Oregon. These GMMs...
Authors
Sean Kamran Ahdi, Brad T. Aagaard, Morgan P. Moschetti, Grace Alexandra Parker, Oliver S. Boyd, William J. Stephenson
USGS automated ground motion processing software USGS automated ground motion processing software
The goal of this project is to update, restructure, and consolidate existing USGS ground-motion processing software to incorporate recent advances from researchers at the USGS, PEER, and others. It will standardize tools for multiple USGS ground-motion products and enable scientists within the USGS and the external community to develop and expand ground-motion datasets used in many...