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.
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 geologic unit
San Francisco Bay region 3D seismic velocity model v21.1
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 21.1 updates only the detailed domain with adjustments to the elastic properties east and north of the San Francisco Bay. There are no changes to the underlying 3D geologic model or the regi
Ground motions from the 2019 Ridgecrest, California, earthquake sequence
This project involves the compilation of ground motions, their derived parameters, and metadata for 133 earthquakes in the 2019 Ridgecrest, California, earthquake sequence. This dataset includes 22,991 records from 133 events from 4 July 2019 to 18 October 2019 with a magnitude range from 3.6 to 7.1.
Filter Total Items: 38
2023 PyLith Hackathon report
The 3rd Pylith Hackathon was held June 12–17, 2023, at the Colorado School of Mines in Golden, Colorado with funding from the Computational Infrastructure for Geodynamics (CIG). The hackathon involved 17 participants working on 5 different projects to implement new features and create new examples for the PyLith crustal deformation modeling software. The projects included (1) spontaneous rupture u
Authors
Brad T. Aagaard
COSMOS Ground-Motion Simulation Working Group workshops #1 and #2
These 2 workshops were held in response to interest generated from sessions on the use of simulated earthquake ground motions at the 2020 and 2021 Consortium of Organizations for Strong Motion Observation Systems (COSMOS) Technical Sessions. The discussions at the Technical Sessions highlighted desires to promote the use of simulated earthquake ground motions for engineering applications and the n
Authors
Brad T. Aagaard, Aysegul Askan, Sanaz Rezaeian, Sean Kamran Ahdi, Alan Yong
Implementation of basin models and sediment depth terms in the 2023 update of the U.S. National Seismic Hazard Model: Example from Reno, Nevada
We present a framework to evaluate the inclusion of candidate basin depth models in the U.S. Geological Survey National Seismic Hazard Model. We compute intensity measures (peak and spectral amplitudes) from uniformly processed earthquake ground motions in and around the basin of interest and compare these to ground-motion model (GMM) estimates over a range of oscillator periods. The GMMs use dept
Authors
Sean Kamran Ahdi, Morgan P. Moschetti, Brad T. Aagaard, Kaitlyn Abernathy, Oliver S. Boyd, William J. Stephenson
2022 Crustal Deformation Modeling Workshop Report
The 2022 Crustal Deformation Modeling Workshop was held June 20–24 at the Colorado School of Mines in Golden, Colorado. The workshop included two days of tutorials on the use of the open-source software PyLith for crustal deformation modeling followed by three days of science talks and discussions. The workshop focused on three primary themes: (1) Earthquake cycle modeling; (2) Inversions for faul
Authors
Brad T. Aagaard, Sylvain Barbot, Brittany Erickson, Matthew Knepley, Mark Simons, Charles Williams
Improving the Development Pipelines for USGS Earthquake Hazards Program Real-Time and Scenario Products
The real-time and scenario products of the U.S. Geological Survey (USGS) Earthquake Hazards Program, such as the ComCat catalog, Did You Feel It?, ShakeMap, ShakeCast, and PAGER, are highly visible and used by a wide variety of stakeholders. We propose two significant enhancements to the development pipelines for the Earthquake Hazards Program real-time and scenario products that have far-reaching
Authors
Brad T. Aagaard, David J. Wald, Eric M. Thompson, Mike Hearne, Lisa Sue Schleicher
2021 Computational Infrastructure for Geodynamics Developers Workshop
The CIG Developers Workshop resulted in a number of recommendations that we think will help expand the CIG developer community, make software more accessible to new users, and increase developer productivity through use of common infrastructure and best practices for software development. This includes building a broad user base with sufficient support through documentation, tutorials, user forums
Authors
Brad T. Aagaard, Jed Brown, Catherin Cooper, Rene Gassmoeller, Lorraine Hwang, Marc Spiegelman
Science plan for improving three-dimensional seismic velocity models in the San Francisco Bay region, 2019–24
This five-year science plan outlines short-term and long-term goals for improving three-dimensional seismic velocity models in the greater San Francisco Bay region as well as how to foster a community effort in reaching those goals. The short-term goals focus on improving the current U.S. Geological Survey San Francisco Bay region geologic and seismic velocity model using existing data. The long-t
Authors
Brad T. Aagaard, Russell W. Graymer, Clifford H. Thurber, Arthur J. Rodgers, Taka'aki Taira, Rufus D. Catchings, Christine A. Goulet, Andreas Plesch
The 2019 Ridgecrest, California, earthquake sequence ground motions: Processed records and derived intensity metrics
Following the 2019 Ridgecrest, California, earthquake sequence, we compiled ground‐motion records from multiple data centers and processed these records using newly developed ground‐motion processing software that performs quality assurance checks, performs standard time series processing steps, and computes a wide range of ground‐motion metrics. In addition, we compute station and waveform metric
Authors
John Rekoske, Eric M. Thompson, Morgan P. Moschetti, Mike Hearne, Brad T. Aagaard, Grace Alexandra Parker
Research to improve ShakeAlert earthquake early warning products and their utility
Earthquake early warning (EEW) is the rapid detection of an earthquake and issuance of an alert or notification to people and vulnerable systems likely to experience potentially damaging ground shaking. The level of ground shaking that is considered damaging is defined by the specific application; for example, manufacturing equipment may experience damage at a lower intensity ground shaking than w
Authors
Elizabeth S. Cochran, Brad T. Aagaard, Richard M. Allen, Jennifer Andrews, Annemarie S. Baltay, Andrew J. Barbour, Paul Bodin, Benjamin A. Brooks, Angela Chung, Brendan W. Crowell, Doug Given, Thomas C. Hanks, J. Renate Hartog, Egill Hauksson, Thomas H. Heaton, Sara McBride, Men-Andrin Meier, Diego Melgar, Sarah E. Minson, Jessica R. Murray, Jennifer A. Strauss, Douglas Toomey
A suite of exercises for verifying dynamic earthquake rupture codes
We describe a set of benchmark exercises that are designed to test if computer codes that simulate dynamic earthquake rupture are working as intended. These types of computer codes are often used to understand how earthquakes operate, and they produce simulation results that include earthquake size, amounts of fault slip, and the patterns of ground shaking and crustal deformation. The benchmark ex
Authors
Ruth A. Harris, Michael Barall, Brad T. Aagaard, Shuo Ma, Daniel Roten, Kim Olsen, Benchun Duan, Dunyu Liu, Bin Luo, Kangchen Bai, Jean-Paul Ampuero, Yoshihiro Kaneko, Alice-Agnes Gabriel, Kenneth Duru, Thomas Ulrich, Stephanie Wollherr, Zheqiang Shi, Eric Dunham, Sam Bydlon, Zhenguo Zhang, Xiaofei Chen, Surendra N. Somala, Christian Pelties, Josue Tago, Victor Manuel Cruz-Atienza, Jeremy Kozdon, Eric Daub, Khurram Aslam, Yuko Kase, Kyle Withers, Luis Dalguer
Integrate urban‐scale seismic hazard analyses with the U.S. National Seismic Hazard Model
For more than 20 yrs, damage patterns and instrumental recordings have highlighted the influence of the local 3D geologic structure on earthquake ground motions (e.g., MM 6.7 Northridge, California, Gao et al., 1996; MM 6.9 Kobe, Japan, Kawase, 1996; MM 6.8 Nisqually, Washington, Frankel, Carver, and Williams, 2002). Although this and other local‐scale features are critical to improving seismic ha
Authors
Morgan P. Moschetti, Nicolas Luco, Arthur Frankel, Mark D. Petersen, Brad T. Aagaard, Annemarie S. Baltay, Michael Blanpied, Oliver S. Boyd, Richard W. Briggs, Ryan D. Gold, Robert Graves, Stephen H. Hartzell, Sanaz Rezaeian, William J. Stephenson, David J. Wald, Robert A. Williams, Kyle Withers
U.S. Geological Survey National Strong-Motion Project strategic plan, 2017–22
The mission of the National Strong-Motion Project is to provide measurements of how the ground and built environment behave during earthquake shaking to the earthquake engineering community, the scientific community, emergency managers, public agencies, industry, media, and other users for the following purposes: Improving engineering evaluations and design methods for facilities and systems;Provi
Authors
Brad T. Aagaard, Mehmet Çelebi, Lind Gee, Robert Graves, Kishor Jaiswal, Erol Kalkan, Keith L. Knudsen, Nicolas Luco, James Smith, Jamison Steidl, Christopher D. Stephens
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 different appli
Science and Products
- Science
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. - Data
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 geologic unitSan Francisco Bay region 3D seismic velocity model v21.1
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 21.1 updates only the detailed domain with adjustments to the elastic properties east and north of the San Francisco Bay. There are no changes to the underlying 3D geologic model or the regiGround motions from the 2019 Ridgecrest, California, earthquake sequence
This project involves the compilation of ground motions, their derived parameters, and metadata for 133 earthquakes in the 2019 Ridgecrest, California, earthquake sequence. This dataset includes 22,991 records from 133 events from 4 July 2019 to 18 October 2019 with a magnitude range from 3.6 to 7.1. - Publications
Filter Total Items: 38
2023 PyLith Hackathon report
The 3rd Pylith Hackathon was held June 12–17, 2023, at the Colorado School of Mines in Golden, Colorado with funding from the Computational Infrastructure for Geodynamics (CIG). The hackathon involved 17 participants working on 5 different projects to implement new features and create new examples for the PyLith crustal deformation modeling software. The projects included (1) spontaneous rupture uAuthorsBrad T. AagaardCOSMOS Ground-Motion Simulation Working Group workshops #1 and #2
These 2 workshops were held in response to interest generated from sessions on the use of simulated earthquake ground motions at the 2020 and 2021 Consortium of Organizations for Strong Motion Observation Systems (COSMOS) Technical Sessions. The discussions at the Technical Sessions highlighted desires to promote the use of simulated earthquake ground motions for engineering applications and the nAuthorsBrad T. Aagaard, Aysegul Askan, Sanaz Rezaeian, Sean Kamran Ahdi, Alan YongImplementation of basin models and sediment depth terms in the 2023 update of the U.S. National Seismic Hazard Model: Example from Reno, Nevada
We present a framework to evaluate the inclusion of candidate basin depth models in the U.S. Geological Survey National Seismic Hazard Model. We compute intensity measures (peak and spectral amplitudes) from uniformly processed earthquake ground motions in and around the basin of interest and compare these to ground-motion model (GMM) estimates over a range of oscillator periods. The GMMs use deptAuthorsSean Kamran Ahdi, Morgan P. Moschetti, Brad T. Aagaard, Kaitlyn Abernathy, Oliver S. Boyd, William J. Stephenson2022 Crustal Deformation Modeling Workshop Report
The 2022 Crustal Deformation Modeling Workshop was held June 20–24 at the Colorado School of Mines in Golden, Colorado. The workshop included two days of tutorials on the use of the open-source software PyLith for crustal deformation modeling followed by three days of science talks and discussions. The workshop focused on three primary themes: (1) Earthquake cycle modeling; (2) Inversions for faulAuthorsBrad T. Aagaard, Sylvain Barbot, Brittany Erickson, Matthew Knepley, Mark Simons, Charles WilliamsImproving the Development Pipelines for USGS Earthquake Hazards Program Real-Time and Scenario Products
The real-time and scenario products of the U.S. Geological Survey (USGS) Earthquake Hazards Program, such as the ComCat catalog, Did You Feel It?, ShakeMap, ShakeCast, and PAGER, are highly visible and used by a wide variety of stakeholders. We propose two significant enhancements to the development pipelines for the Earthquake Hazards Program real-time and scenario products that have far-reachingAuthorsBrad T. Aagaard, David J. Wald, Eric M. Thompson, Mike Hearne, Lisa Sue Schleicher2021 Computational Infrastructure for Geodynamics Developers Workshop
The CIG Developers Workshop resulted in a number of recommendations that we think will help expand the CIG developer community, make software more accessible to new users, and increase developer productivity through use of common infrastructure and best practices for software development. This includes building a broad user base with sufficient support through documentation, tutorials, user forumsAuthorsBrad T. Aagaard, Jed Brown, Catherin Cooper, Rene Gassmoeller, Lorraine Hwang, Marc SpiegelmanScience plan for improving three-dimensional seismic velocity models in the San Francisco Bay region, 2019–24
This five-year science plan outlines short-term and long-term goals for improving three-dimensional seismic velocity models in the greater San Francisco Bay region as well as how to foster a community effort in reaching those goals. The short-term goals focus on improving the current U.S. Geological Survey San Francisco Bay region geologic and seismic velocity model using existing data. The long-tAuthorsBrad T. Aagaard, Russell W. Graymer, Clifford H. Thurber, Arthur J. Rodgers, Taka'aki Taira, Rufus D. Catchings, Christine A. Goulet, Andreas PleschThe 2019 Ridgecrest, California, earthquake sequence ground motions: Processed records and derived intensity metrics
Following the 2019 Ridgecrest, California, earthquake sequence, we compiled ground‐motion records from multiple data centers and processed these records using newly developed ground‐motion processing software that performs quality assurance checks, performs standard time series processing steps, and computes a wide range of ground‐motion metrics. In addition, we compute station and waveform metricAuthorsJohn Rekoske, Eric M. Thompson, Morgan P. Moschetti, Mike Hearne, Brad T. Aagaard, Grace Alexandra ParkerResearch to improve ShakeAlert earthquake early warning products and their utility
Earthquake early warning (EEW) is the rapid detection of an earthquake and issuance of an alert or notification to people and vulnerable systems likely to experience potentially damaging ground shaking. The level of ground shaking that is considered damaging is defined by the specific application; for example, manufacturing equipment may experience damage at a lower intensity ground shaking than wAuthorsElizabeth S. Cochran, Brad T. Aagaard, Richard M. Allen, Jennifer Andrews, Annemarie S. Baltay, Andrew J. Barbour, Paul Bodin, Benjamin A. Brooks, Angela Chung, Brendan W. Crowell, Doug Given, Thomas C. Hanks, J. Renate Hartog, Egill Hauksson, Thomas H. Heaton, Sara McBride, Men-Andrin Meier, Diego Melgar, Sarah E. Minson, Jessica R. Murray, Jennifer A. Strauss, Douglas ToomeyA suite of exercises for verifying dynamic earthquake rupture codes
We describe a set of benchmark exercises that are designed to test if computer codes that simulate dynamic earthquake rupture are working as intended. These types of computer codes are often used to understand how earthquakes operate, and they produce simulation results that include earthquake size, amounts of fault slip, and the patterns of ground shaking and crustal deformation. The benchmark exAuthorsRuth A. Harris, Michael Barall, Brad T. Aagaard, Shuo Ma, Daniel Roten, Kim Olsen, Benchun Duan, Dunyu Liu, Bin Luo, Kangchen Bai, Jean-Paul Ampuero, Yoshihiro Kaneko, Alice-Agnes Gabriel, Kenneth Duru, Thomas Ulrich, Stephanie Wollherr, Zheqiang Shi, Eric Dunham, Sam Bydlon, Zhenguo Zhang, Xiaofei Chen, Surendra N. Somala, Christian Pelties, Josue Tago, Victor Manuel Cruz-Atienza, Jeremy Kozdon, Eric Daub, Khurram Aslam, Yuko Kase, Kyle Withers, Luis DalguerIntegrate urban‐scale seismic hazard analyses with the U.S. National Seismic Hazard Model
For more than 20 yrs, damage patterns and instrumental recordings have highlighted the influence of the local 3D geologic structure on earthquake ground motions (e.g., MM 6.7 Northridge, California, Gao et al., 1996; MM 6.9 Kobe, Japan, Kawase, 1996; MM 6.8 Nisqually, Washington, Frankel, Carver, and Williams, 2002). Although this and other local‐scale features are critical to improving seismic haAuthorsMorgan P. Moschetti, Nicolas Luco, Arthur Frankel, Mark D. Petersen, Brad T. Aagaard, Annemarie S. Baltay, Michael Blanpied, Oliver S. Boyd, Richard W. Briggs, Ryan D. Gold, Robert Graves, Stephen H. Hartzell, Sanaz Rezaeian, William J. Stephenson, David J. Wald, Robert A. Williams, Kyle WithersU.S. Geological Survey National Strong-Motion Project strategic plan, 2017–22
The mission of the National Strong-Motion Project is to provide measurements of how the ground and built environment behave during earthquake shaking to the earthquake engineering community, the scientific community, emergency managers, public agencies, industry, media, and other users for the following purposes: Improving engineering evaluations and design methods for facilities and systems;ProviAuthorsBrad T. Aagaard, Mehmet Çelebi, Lind Gee, Robert Graves, Kishor Jaiswal, Erol Kalkan, Keith L. Knudsen, Nicolas Luco, James Smith, Jamison Steidl, Christopher D. Stephens - 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 different appli