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
Filter Total Items: 50
The 1906 San Francisco earthquake a century later: Introduction to the special section 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)...
Authors
Brad T. Aagaard, Gregory C. Beroza
Visualizing the ground motions of the 1906 San Francisco earthquake 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...
Authors
A. Chourasia, S. Cutchin, Brad T. Aagaard
Ground-motion modeling of the 1906 San Francisco earthquake, part I: Validation using the 1989 Loma Prieta earthquake 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...
Authors
Brad T. Aagaard, T.M. Brocher, D. Dolenc, D. Dreger, R.W. Graves, S. Harmsen, S. Hartzell, S. Larsen, M.L. Zoback
Constraining fault constitutive behavior with slip and stress heterogeneity 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...
Authors
Brad T. Aagaard, T. H. Heaton
Ground-motion modeling of the 1906 San Francisco Earthquake, part II: Ground-motion estimates for the 1906 earthquake and scenario events 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...
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
Broadband simulations for Mw 7.8 southern san andreas earthquakes: Ground motion sensitivity to rupture speed 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...
Authors
R.W. Graves, Brad T. Aagaard, K.W. Hudnut, L.M. Star, J.P. Stewart, T.H. Jordan
Science and Products
Filter Total Items: 50
The 1906 San Francisco earthquake a century later: Introduction to the special section 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)...
Authors
Brad T. Aagaard, Gregory C. Beroza
Visualizing the ground motions of the 1906 San Francisco earthquake 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...
Authors
A. Chourasia, S. Cutchin, Brad T. Aagaard
Ground-motion modeling of the 1906 San Francisco earthquake, part I: Validation using the 1989 Loma Prieta earthquake 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...
Authors
Brad T. Aagaard, T.M. Brocher, D. Dolenc, D. Dreger, R.W. Graves, S. Harmsen, S. Hartzell, S. Larsen, M.L. Zoback
Constraining fault constitutive behavior with slip and stress heterogeneity 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...
Authors
Brad T. Aagaard, T. H. Heaton
Ground-motion modeling of the 1906 San Francisco Earthquake, part II: Ground-motion estimates for the 1906 earthquake and scenario events 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...
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
Broadband simulations for Mw 7.8 southern san andreas earthquakes: Ground motion sensitivity to rupture speed 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...
Authors
R.W. Graves, Brad T. Aagaard, K.W. Hudnut, L.M. Star, J.P. Stewart, T.H. Jordan