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: 51
The SCEC/USGS dynamic earthquake rupture code verification exercise 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...
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 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
Long-period building response to earthquakes in the San Francisco Bay Area 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...
Authors
A.H. Olsen, Brad T. Aagaard, T. H. Heaton
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
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
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
Science and Products
Filter Total Items: 51
The SCEC/USGS dynamic earthquake rupture code verification exercise 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...
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 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
Long-period building response to earthquakes in the San Francisco Bay Area 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...
Authors
A.H. Olsen, Brad T. Aagaard, T. H. Heaton
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
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
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