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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

No Result Found
Filter Total Items: 40

Data files for ground-motion simulations of the 1906 San Francisco earthquake and scenario earthquakes on the Northern San Andreas Fault

This data set contains results from ground-motion simulations of the 1906 San Francisco earthquake, seven hypothetical earthquakes on the northern San Andreas Fault, and the 1989 Loma Prieta earthquake. The bulk of the data consists of synthetic velocity time-histories. Peak ground velocity on a 1/60th degree grid and geodetic displacements from the simulations are also included. Details of the gr
Authors
Brad T. Aagaard, Michael Barall, Thomas M. Brocher, David Dolenc, Douglas Dreger, Robert W. Graves, Stephen Harmsen, Stephen H. Hartzell, Shawn Larsen, Kathleen McCandless, Stefan Nilsson, N. Anders Petersson, Arthur Rodgers, Bjorn Sjogreen, Mary Lou Zoback
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center, Geologic Hazards Science Center

The SCEC/USGS dynamic earthquake rupture code verification exercise

Numerical simulations of earthquake rupture dynamics are now common, yet it has been difficult to test the validity of these simulations because there have been few field observations and no analytic solutions with which to compare the results. This paper describes the Southern California Earthquake Center/U.S. Geological Survey (SCEC/USGS) Dynamic Earthquake Rupture Code Verification Exercise, wh
Authors
R. A. Harris, M. Barall, R. Archuleta, E. Dunham, Brad T. Aagaard, J.-P. Ampuero, H. Bhat, Victor M. Cruz-Atienza, L. Dalguer, P. Dawson, S. Day, B. Duan, G. Ely, Y. Kaneko, Y. Kase, N. Lapusta, Yajing Liu, S. Ma, D. Oglesby, K. Olsen, A. Pitarka, S. Song, E. Templeton

The 1906 San Francisco earthquake a century later: Introduction to the special section

The great 1906 San Francisco earthquake is perhaps the landmark event in the history of earthquake science. It began with a foreshock at 5:12 a.m. local time in the morning of 18 April 1906. Some 30 sec later, the main event initiated on the San Andreas fault, just off the San Francisco coast (Lawson, 1908). Within 90 sec, nearly 480 km of the San Andreas fault ruptured (see Fig. 1), extending sou
Authors
Brad T. Aagaard, Gregory C. Beroza
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Broadband simulations for Mw 7.8 southern san andreas earthquakes: Ground motion sensitivity to rupture speed

Using the high-performance computing resources of the Southern California Earthquake Center, we simulate broadband (0-10 Hz) ground motions for three Mw 7.8 rupture scenarios of the southern San Andreas fault. The scenarios incorporate a kinematic rupture description with the average rupture speed along the large slip portions of the fault set at 0.96, 0.89, and 0.84 times the local shear wave vel
Authors
R.W. Graves, Brad T. Aagaard, K.W. Hudnut, L.M. Star, J.P. Stewart, T.H. Jordan

Long-period building response to earthquakes in the San Francisco Bay Area

This article reports a study of modeled, long-period building responses to ground-motion simulations of earthquakes in the San Francisco Bay Area. The earthquakes include the 1989 magnitude 6.9 Loma Prieta earthquake, a magnitude 7.8 simulation of the 1906 San Francisco earthquake, and two hypothetical magnitude 7.8 northern San Andreas fault earthquakes with hypocenters north and south of San Fra
Authors
A.H. Olsen, Brad T. Aagaard, T. H. Heaton

Ground-motion modeling of the 1906 San Francisco earthquake, part I: Validation using the 1989 Loma Prieta earthquake

We compute ground motions for the Beroza (1991) and Wald et al. (1991) source models of the 1989 magnitude 6.9 Loma Prieta earthquake using four different wave-propagation codes and recently developed 3D geologic and seismic velocity models. In preparation for modeling the 1906 San Francisco earthquake, we use this well-recorded earthquake to characterize how well our ground-motion simulations rep
Authors
Brad T. Aagaard, T. M. Brocher, D. Dolenc, D. Dreger, R.W. Graves, S. Harmsen, S. Hartzell, S. Larsen, M.L. Zoback

Ground-motion modeling of the 1906 San Francisco Earthquake, part II: Ground-motion estimates for the 1906 earthquake and scenario events

We estimate the ground motions produce by the 1906 San Francisco earthquake making use of the recently developed Song et al. (2008) source model that combines the available geodetic and seismic observations and recently constructed 3D geologic and seismic velocity models. Our estimates of the ground motions for the 1906 earthquake are consistent across five ground-motion modeling groups employing
Authors
Brad T. Aagaard, T. M. Brocher, D. Dolenc, D. Dreger, R.W. Graves, S. Harmsen, S. Hartzell, S. Larsen, K. McCandless, S. Nilsson, N.A. Petersson, A. Rodgers, B. Sjogreen, M.L. Zoback

Constraining fault constitutive behavior with slip and stress heterogeneity

We study how enforcing self-consistency in the statistical properties of the preshear and postshear stress on a fault can be used to constrain fault constitutive behavior beyond that required to produce a desired spatial and temporal evolution of slip in a single event. We explore features of rupture dynamics that (1) lead to slip heterogeneity in earthquake ruptures and (2) maintain these conditi
Authors
Brad T. Aagaard, T. H. Heaton

Visualizing the ground motions of the 1906 San Francisco earthquake

With advances in computational capabilities and refinement of seismic wave-propagation models in the past decade large three-dimensional simulations of earthquake ground motion have become possible. The resulting datasets from these simulations are multivariate, temporal and multi-terabyte in size. Past visual representations of results from seismic studies have been largely confined to static two
Authors
A. Chourasia, S. Cutchin, Brad T. Aagaard

Basin structure beneath the Santa Rosa Plain, Northern California: Implications for damage caused by the 1969 Santa Rosa and 1906 San Francisco earthquakes

Regional gravity data in the northern San Francisco Bay region reflect a complex basin configuration beneath the Santa Rosa plain that likely contributed to the significant damage to the city of Santa Rosa caused by the 1969 M 5.6, 5.7 Santa Rosa earthquakes and the 1906 M 7.9 San Francisco earthquake. Inversion of these data indicates that the Santa Rosa plain is underlain by two sedimentary basi
Authors
D.K. McPhee, V. E. Langenheim, S. Hartzell, R. J. McLaughlin, Brad T. Aagaard, R.C. Jachens, C. McCabe
By
Geology, Minerals, Energy, and Geophysics Science Center

Implications for prediction and hazard assessment from the 2004 Parkfield earthquake

Obtaining high-quality measurements close to a large earthquake is not easy: one has to be in the right place at the right time with the right instruments. Such a convergence happened, for the first time, when the 28 September 2004 Parkfield, California, earthquake occurred on the San Andreas fault in the middle of a dense network of instruments designed to record it. The resulting data reveal asp
Authors
W. H. Bakun, Brad T. Aagaard, B. Dost, William L. Ellsworth, Jeanne L. Hardebeck, Ruth A. Harris, C. Ji, Malcolm J. S. Johnston, John O. Langbein, James J. Lienkaemper, Andrew J. Michael, Jessica R. Murray, R.M. Nadeau, P.A. Reasenberg, M.S. Reichle, Evelyn A. Roeloffs, A. Shakal, Robert W. Simpson, F. Waldhauser

Teleseismic body waves from dynamically rupturing shallow thrust faults: Are they opaque for surface-reflected phases?

We investigate whether a shallow-dipping thrust fault is prone to waveslip interactions via surface-reflected waves affecting the dynamic slip. If so, can these interactions create faults that are opaque to radiated energy? Furthermore, in this case of a shallow-dipping thrust fault, can incorrectly assuming a transparent fault while using dislocation theory lead to underestimates of seismic momen
Authors
D.E. Smith, Brad T. Aagaard, T. H. Heaton

Science and Products

  • Science
  • Data
    No Result Found
  • Publications
    Filter Total Items: 40

    Data files for ground-motion simulations of the 1906 San Francisco earthquake and scenario earthquakes on the Northern San Andreas Fault

    This data set contains results from ground-motion simulations of the 1906 San Francisco earthquake, seven hypothetical earthquakes on the northern San Andreas Fault, and the 1989 Loma Prieta earthquake. The bulk of the data consists of synthetic velocity time-histories. Peak ground velocity on a 1/60th degree grid and geodetic displacements from the simulations are also included. Details of the gr
    Authors
    Brad T. Aagaard, Michael Barall, Thomas M. Brocher, David Dolenc, Douglas Dreger, Robert W. Graves, Stephen Harmsen, Stephen H. Hartzell, Shawn Larsen, Kathleen McCandless, Stefan Nilsson, N. Anders Petersson, Arthur Rodgers, Bjorn Sjogreen, Mary Lou Zoback
    By
    Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center, Geologic Hazards Science Center

    The SCEC/USGS dynamic earthquake rupture code verification exercise

    Numerical simulations of earthquake rupture dynamics are now common, yet it has been difficult to test the validity of these simulations because there have been few field observations and no analytic solutions with which to compare the results. This paper describes the Southern California Earthquake Center/U.S. Geological Survey (SCEC/USGS) Dynamic Earthquake Rupture Code Verification Exercise, wh
    Authors
    R. A. Harris, M. Barall, R. Archuleta, E. Dunham, Brad T. Aagaard, J.-P. Ampuero, H. Bhat, Victor M. Cruz-Atienza, L. Dalguer, P. Dawson, S. Day, B. Duan, G. Ely, Y. Kaneko, Y. Kase, N. Lapusta, Yajing Liu, S. Ma, D. Oglesby, K. Olsen, A. Pitarka, S. Song, E. Templeton

    The 1906 San Francisco earthquake a century later: Introduction to the special section

    The great 1906 San Francisco earthquake is perhaps the landmark event in the history of earthquake science. It began with a foreshock at 5:12 a.m. local time in the morning of 18 April 1906. Some 30 sec later, the main event initiated on the San Andreas fault, just off the San Francisco coast (Lawson, 1908). Within 90 sec, nearly 480 km of the San Andreas fault ruptured (see Fig. 1), extending sou
    Authors
    Brad T. Aagaard, Gregory C. Beroza
    By
    Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

    Broadband simulations for Mw 7.8 southern san andreas earthquakes: Ground motion sensitivity to rupture speed

    Using the high-performance computing resources of the Southern California Earthquake Center, we simulate broadband (0-10 Hz) ground motions for three Mw 7.8 rupture scenarios of the southern San Andreas fault. The scenarios incorporate a kinematic rupture description with the average rupture speed along the large slip portions of the fault set at 0.96, 0.89, and 0.84 times the local shear wave vel
    Authors
    R.W. Graves, Brad T. Aagaard, K.W. Hudnut, L.M. Star, J.P. Stewart, T.H. Jordan

    Long-period building response to earthquakes in the San Francisco Bay Area

    This article reports a study of modeled, long-period building responses to ground-motion simulations of earthquakes in the San Francisco Bay Area. The earthquakes include the 1989 magnitude 6.9 Loma Prieta earthquake, a magnitude 7.8 simulation of the 1906 San Francisco earthquake, and two hypothetical magnitude 7.8 northern San Andreas fault earthquakes with hypocenters north and south of San Fra
    Authors
    A.H. Olsen, Brad T. Aagaard, T. H. Heaton

    Ground-motion modeling of the 1906 San Francisco earthquake, part I: Validation using the 1989 Loma Prieta earthquake

    We compute ground motions for the Beroza (1991) and Wald et al. (1991) source models of the 1989 magnitude 6.9 Loma Prieta earthquake using four different wave-propagation codes and recently developed 3D geologic and seismic velocity models. In preparation for modeling the 1906 San Francisco earthquake, we use this well-recorded earthquake to characterize how well our ground-motion simulations rep
    Authors
    Brad T. Aagaard, T. M. Brocher, D. Dolenc, D. Dreger, R.W. Graves, S. Harmsen, S. Hartzell, S. Larsen, M.L. Zoback

    Ground-motion modeling of the 1906 San Francisco Earthquake, part II: Ground-motion estimates for the 1906 earthquake and scenario events

    We estimate the ground motions produce by the 1906 San Francisco earthquake making use of the recently developed Song et al. (2008) source model that combines the available geodetic and seismic observations and recently constructed 3D geologic and seismic velocity models. Our estimates of the ground motions for the 1906 earthquake are consistent across five ground-motion modeling groups employing
    Authors
    Brad T. Aagaard, T. M. Brocher, D. Dolenc, D. Dreger, R.W. Graves, S. Harmsen, S. Hartzell, S. Larsen, K. McCandless, S. Nilsson, N.A. Petersson, A. Rodgers, B. Sjogreen, M.L. Zoback

    Constraining fault constitutive behavior with slip and stress heterogeneity

    We study how enforcing self-consistency in the statistical properties of the preshear and postshear stress on a fault can be used to constrain fault constitutive behavior beyond that required to produce a desired spatial and temporal evolution of slip in a single event. We explore features of rupture dynamics that (1) lead to slip heterogeneity in earthquake ruptures and (2) maintain these conditi
    Authors
    Brad T. Aagaard, T. H. Heaton

    Visualizing the ground motions of the 1906 San Francisco earthquake

    With advances in computational capabilities and refinement of seismic wave-propagation models in the past decade large three-dimensional simulations of earthquake ground motion have become possible. The resulting datasets from these simulations are multivariate, temporal and multi-terabyte in size. Past visual representations of results from seismic studies have been largely confined to static two
    Authors
    A. Chourasia, S. Cutchin, Brad T. Aagaard

    Basin structure beneath the Santa Rosa Plain, Northern California: Implications for damage caused by the 1969 Santa Rosa and 1906 San Francisco earthquakes

    Regional gravity data in the northern San Francisco Bay region reflect a complex basin configuration beneath the Santa Rosa plain that likely contributed to the significant damage to the city of Santa Rosa caused by the 1969 M 5.6, 5.7 Santa Rosa earthquakes and the 1906 M 7.9 San Francisco earthquake. Inversion of these data indicates that the Santa Rosa plain is underlain by two sedimentary basi
    Authors
    D.K. McPhee, V. E. Langenheim, S. Hartzell, R. J. McLaughlin, Brad T. Aagaard, R.C. Jachens, C. McCabe
    By
    Geology, Minerals, Energy, and Geophysics Science Center

    Implications for prediction and hazard assessment from the 2004 Parkfield earthquake

    Obtaining high-quality measurements close to a large earthquake is not easy: one has to be in the right place at the right time with the right instruments. Such a convergence happened, for the first time, when the 28 September 2004 Parkfield, California, earthquake occurred on the San Andreas fault in the middle of a dense network of instruments designed to record it. The resulting data reveal asp
    Authors
    W. H. Bakun, Brad T. Aagaard, B. Dost, William L. Ellsworth, Jeanne L. Hardebeck, Ruth A. Harris, C. Ji, Malcolm J. S. Johnston, John O. Langbein, James J. Lienkaemper, Andrew J. Michael, Jessica R. Murray, R.M. Nadeau, P.A. Reasenberg, M.S. Reichle, Evelyn A. Roeloffs, A. Shakal, Robert W. Simpson, F. Waldhauser

    Teleseismic body waves from dynamically rupturing shallow thrust faults: Are they opaque for surface-reflected phases?

    We investigate whether a shallow-dipping thrust fault is prone to waveslip interactions via surface-reflected waves affecting the dynamic slip. If so, can these interactions create faults that are opaque to radiated energy? Furthermore, in this case of a shallow-dipping thrust fault, can incorrectly assuming a transparent fault while using dislocation theory lead to underestimates of seismic momen
    Authors
    D.E. Smith, Brad T. Aagaard, T. H. Heaton
  • Software