Tom Parsons
I conduct research aimed at improving our ability to forecast hazardous events like earthquakes and tsunamis. Specifically, I study how earthquakes trigger others, how crustal movements cause earthquake stresses, and how to convert geologic observations of earthquake and tsunami processes into quantitative forecasts of use to planners, insurers, and builders.
Professional Experience
1994-Present: Research Geophysicist, U. S. Geological Survey, Moffett Field, CA
1992-1994: National Research Council Postdoctoral Fellow
Education and Certifications
1992 – Ph.D. in Geophysics, Stanford University
1990 – M.S. in Geophysics, Stanford University
1988 – B.S. in Applied Geophysics, UCLA
Affiliations and Memberships*
Editor, AGU Advances, 2019-2022
Member: Executive Committee, Council of Senior Science Advisors (COSSA), 2015-present
Editor in Chief, Journal of Geophysical Research, Solid Earth, 2009-2015
Editor in Chief, Tectonophysics, 2007-2009
Editorial Board, Tectonophysics, 2005-2007
Editorial Board, Geology, 1995-2000, 2005-2008
Member: Executive Committee, Working Group on California Earthquake Probabilities 2005-2014
Member: SCEC Planning Committee, 2007-2009
Honors and Awards
Senior Scientist (ST): 1/15
Fellow American Geophysical Union, Elected 1/12
Fulbright Mutual Educational Exchange Grant USA-Greece: 2007-2008
Alumni Pillar of Achievement: Golden West College Outstanding Alumni Award (10/07)
Fellow Geological Society of America, Elected 10/97
Shoemaker Communication Award (10/00)
National Association of Government Communicators Gold Screen Award (12/00)
National Research Council Post-Doctoral Fellow (8/92)
Science and Products
Filter Total Items: 120
Persistent earthquake clusters and gaps from slip on irregular faults Persistent earthquake clusters and gaps from slip on irregular faults
Earthquake-producing fault systems like the San Andreas fault in California show self-similar structural variation1; earthquakes cluster in space, leaving aseismic gaps between clusters. Whether gaps represent overdue earthquakes or signify diminished risk is a question with which seismic-hazard forecasters wrestle1,2,3,4,5. Here I use spectral analysis of the spatial distribution of...
Authors
Tom Parsons
Why the sacramento delta area differs from other parts of the great valley: numerical modeling of thermal structure and thermal subsidence of forearc basins Why the sacramento delta area differs from other parts of the great valley: numerical modeling of thermal structure and thermal subsidence of forearc basins
Data on present-day heat flow, subsidence history, and paleotemperature for the Sacramento Delta region, California, have been employed to constrain a numerical model of tectonic subsidence and thermal evolution of forearc basins. The model assumes an oceanic basement with an initial thermal profile dependent on its age subjected to refrigeration caused by a subducting slab. Subsidence...
Authors
V.O. Mikhailov, T. Parsons, R.W. Simpson, E.P. Timoshkina, C. Williams
Forecast experiment: do temporal and spatial b value variations along the Calaveras fault portend M ≥ 4.0 earthquakes? Forecast experiment: do temporal and spatial b value variations along the Calaveras fault portend M ≥ 4.0 earthquakes?
The power law distribution of earthquake magnitudes and frequencies is a fundamental scaling relationship used for forecasting. However, can its slope (b value) be used on individual faults as a stress indicator? Some have concluded that b values drop just before large shocks. Others suggested that temporally stable low b value zones identify future large-earthquake locations. This study...
Authors
Tom Parsons
Static stress change from the 8 October, 2005 M = 7.6 Kashmir earthquake Static stress change from the 8 October, 2005 M = 7.6 Kashmir earthquake
We calculated static stress changes from the devastating M = 7.6 earthquake that shook Kashmir on 8 October, 2005. We mapped Coulomb stress change on target fault planes oriented by assuming a regional compressional stress regime with greatest principal stress directed orthogonally to the mainshock strike. We tested calculation sensitivity by varying assumed stress orientations, target...
Authors
T. Parsons, R.S. Yeats, Y. Yagi, A. Hussain
M ≥ 7.0 earthquake recurrence on the San Andreas fault from a stress renewal model M ≥ 7.0 earthquake recurrence on the San Andreas fault from a stress renewal model
Forecasting M ≥ 7.0 San Andreas fault earthquakes requires an assessment of their expected frequency. I used a three-dimensional finite element model of California to calculate volumetric static stress drops from scenario M ≥ 7.0 earthquakes on three San Andreas fault sections. The ratio of stress drop to tectonic stressing rate derived from geodetic displacements yielded recovery times...
Authors
Thomas E. Parsons
Earthquake and volcano clustering via stress transfer at Yucca Mountain, Nevada Earthquake and volcano clustering via stress transfer at Yucca Mountain, Nevada
The proposed national high-level nuclear waste repository at Yucca Mountain is close to Quaternary cinder cones and faults with Quaternary slip. Volcano eruption and earthquake frequencies are low, with indications of spatial and temporal clustering, making probabilistic assessments difficult. In an effort to identify the most likely intrusion sites, we based a three-dimensional finite...
Authors
T. Parsons, G. A. Thompson, A.H. Cogbill
A new probabilistic seismic hazard assessment for greater Tokyo A new probabilistic seismic hazard assessment for greater Tokyo
Tokyo and its outlying cities are home to one-quarter of Japan's 127 million people. Highly destructive earthquakes struck the capital in 1703, 1855 and 1923, the last of which took 105 000 lives. Fuelled by greater Tokyo's rich seismological record, but challenged by its magnificent complexity, our joint Japanese-US group carried out a new study of the capital's earthquake hazards. We...
Authors
R.S. Stein, S. Toda, T. Parsons, E. Grunewald, R. Blong, S. Sparks, H. Shah, J. Kennedy
Probabilistic analysis of tsunami hazards Probabilistic analysis of tsunami hazards
Determining the likelihood of a disaster is a key component of any comprehensive hazard assessment. This is particularly true for tsunamis, even though most tsunami hazard assessments have in the past relied on scenario or deterministic type models. We discuss probabilistic tsunami hazard analysis (PTHA) from the standpoint of integrating computational methods with empirical analysis of...
Authors
E.L. Geist, T. Parsons
Tectonic stressing in California modeled from GPS observations Tectonic stressing in California modeled from GPS observations
What happens in the crust as a result of geodetically observed secular motions? In this paper we find out by distorting a finite element model of California using GPS-derived displacements. A complex model was constructed using spatially varying crustal thickness, geothermal gradient, topography, and creeping faults. GPS velocity observations were interpolated and extrapolated across the...
Authors
T. Parsons
Correction to “A hypothesis for delayed dynamic earthquake triggering” Correction to “A hypothesis for delayed dynamic earthquake triggering”
No abstract available.
Authors
Tom Parsons
Triggering of tsunamigenic aftershocks from large strike‐slip earthquakes: Analysis of the November 2000 New Ireland earthquake sequence Triggering of tsunamigenic aftershocks from large strike‐slip earthquakes: Analysis of the November 2000 New Ireland earthquake sequence
[1] The November 2000 New Ireland earthquake sequence started with a Mw = 8.0 left‐lateral main shock on 16 November and was followed by a series of aftershocks with primarily thrust mechanisms. The earthquake sequence was associated with a locally damaging tsunami on the islands of New Ireland and nearby New Britain, Bougainville, and Buka. Results from numerical tsunami‐propagation...
Authors
Eric L. Geist, Tom Parsons
Structure and mechanics of the San Andreas–San Gregorio fault junction, San Francisco, California Structure and mechanics of the San Andreas–San Gregorio fault junction, San Francisco, California
[1] The right‐lateral San Gregorio and San Andreas faults meet west of the Golden Gate near San Francisco. Coincident seismic reflection and refraction profiling across the San Gregorio and San Andreas faults south of their junction shows the crust between them to have formed shallow extensional basins that are dissected by parallel strike‐slip faults. We employ a regional finite element...
Authors
Tom Parsons, Terry R. Bruns, Ray W. Sliter
Non-USGS Publications**
1992, by Parsons, T. et al., Department of Geophysics, Stanford University
1992, by Parsons, T., et al., Department of Geophysics, Stanford University
1991, by Howie, J.M., et al., Department of Geophysics, Stanford University
1991, by Parsons, T., and Thompson, G.A., Department of Geophysics, Stanford University
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Filter Total Items: 120
Persistent earthquake clusters and gaps from slip on irregular faults Persistent earthquake clusters and gaps from slip on irregular faults
Earthquake-producing fault systems like the San Andreas fault in California show self-similar structural variation1; earthquakes cluster in space, leaving aseismic gaps between clusters. Whether gaps represent overdue earthquakes or signify diminished risk is a question with which seismic-hazard forecasters wrestle1,2,3,4,5. Here I use spectral analysis of the spatial distribution of...
Authors
Tom Parsons
Why the sacramento delta area differs from other parts of the great valley: numerical modeling of thermal structure and thermal subsidence of forearc basins Why the sacramento delta area differs from other parts of the great valley: numerical modeling of thermal structure and thermal subsidence of forearc basins
Data on present-day heat flow, subsidence history, and paleotemperature for the Sacramento Delta region, California, have been employed to constrain a numerical model of tectonic subsidence and thermal evolution of forearc basins. The model assumes an oceanic basement with an initial thermal profile dependent on its age subjected to refrigeration caused by a subducting slab. Subsidence...
Authors
V.O. Mikhailov, T. Parsons, R.W. Simpson, E.P. Timoshkina, C. Williams
Forecast experiment: do temporal and spatial b value variations along the Calaveras fault portend M ≥ 4.0 earthquakes? Forecast experiment: do temporal and spatial b value variations along the Calaveras fault portend M ≥ 4.0 earthquakes?
The power law distribution of earthquake magnitudes and frequencies is a fundamental scaling relationship used for forecasting. However, can its slope (b value) be used on individual faults as a stress indicator? Some have concluded that b values drop just before large shocks. Others suggested that temporally stable low b value zones identify future large-earthquake locations. This study...
Authors
Tom Parsons
Static stress change from the 8 October, 2005 M = 7.6 Kashmir earthquake Static stress change from the 8 October, 2005 M = 7.6 Kashmir earthquake
We calculated static stress changes from the devastating M = 7.6 earthquake that shook Kashmir on 8 October, 2005. We mapped Coulomb stress change on target fault planes oriented by assuming a regional compressional stress regime with greatest principal stress directed orthogonally to the mainshock strike. We tested calculation sensitivity by varying assumed stress orientations, target...
Authors
T. Parsons, R.S. Yeats, Y. Yagi, A. Hussain
M ≥ 7.0 earthquake recurrence on the San Andreas fault from a stress renewal model M ≥ 7.0 earthquake recurrence on the San Andreas fault from a stress renewal model
Forecasting M ≥ 7.0 San Andreas fault earthquakes requires an assessment of their expected frequency. I used a three-dimensional finite element model of California to calculate volumetric static stress drops from scenario M ≥ 7.0 earthquakes on three San Andreas fault sections. The ratio of stress drop to tectonic stressing rate derived from geodetic displacements yielded recovery times...
Authors
Thomas E. Parsons
Earthquake and volcano clustering via stress transfer at Yucca Mountain, Nevada Earthquake and volcano clustering via stress transfer at Yucca Mountain, Nevada
The proposed national high-level nuclear waste repository at Yucca Mountain is close to Quaternary cinder cones and faults with Quaternary slip. Volcano eruption and earthquake frequencies are low, with indications of spatial and temporal clustering, making probabilistic assessments difficult. In an effort to identify the most likely intrusion sites, we based a three-dimensional finite...
Authors
T. Parsons, G. A. Thompson, A.H. Cogbill
A new probabilistic seismic hazard assessment for greater Tokyo A new probabilistic seismic hazard assessment for greater Tokyo
Tokyo and its outlying cities are home to one-quarter of Japan's 127 million people. Highly destructive earthquakes struck the capital in 1703, 1855 and 1923, the last of which took 105 000 lives. Fuelled by greater Tokyo's rich seismological record, but challenged by its magnificent complexity, our joint Japanese-US group carried out a new study of the capital's earthquake hazards. We...
Authors
R.S. Stein, S. Toda, T. Parsons, E. Grunewald, R. Blong, S. Sparks, H. Shah, J. Kennedy
Probabilistic analysis of tsunami hazards Probabilistic analysis of tsunami hazards
Determining the likelihood of a disaster is a key component of any comprehensive hazard assessment. This is particularly true for tsunamis, even though most tsunami hazard assessments have in the past relied on scenario or deterministic type models. We discuss probabilistic tsunami hazard analysis (PTHA) from the standpoint of integrating computational methods with empirical analysis of...
Authors
E.L. Geist, T. Parsons
Tectonic stressing in California modeled from GPS observations Tectonic stressing in California modeled from GPS observations
What happens in the crust as a result of geodetically observed secular motions? In this paper we find out by distorting a finite element model of California using GPS-derived displacements. A complex model was constructed using spatially varying crustal thickness, geothermal gradient, topography, and creeping faults. GPS velocity observations were interpolated and extrapolated across the...
Authors
T. Parsons
Correction to “A hypothesis for delayed dynamic earthquake triggering” Correction to “A hypothesis for delayed dynamic earthquake triggering”
No abstract available.
Authors
Tom Parsons
Triggering of tsunamigenic aftershocks from large strike‐slip earthquakes: Analysis of the November 2000 New Ireland earthquake sequence Triggering of tsunamigenic aftershocks from large strike‐slip earthquakes: Analysis of the November 2000 New Ireland earthquake sequence
[1] The November 2000 New Ireland earthquake sequence started with a Mw = 8.0 left‐lateral main shock on 16 November and was followed by a series of aftershocks with primarily thrust mechanisms. The earthquake sequence was associated with a locally damaging tsunami on the islands of New Ireland and nearby New Britain, Bougainville, and Buka. Results from numerical tsunami‐propagation...
Authors
Eric L. Geist, Tom Parsons
Structure and mechanics of the San Andreas–San Gregorio fault junction, San Francisco, California Structure and mechanics of the San Andreas–San Gregorio fault junction, San Francisco, California
[1] The right‐lateral San Gregorio and San Andreas faults meet west of the Golden Gate near San Francisco. Coincident seismic reflection and refraction profiling across the San Gregorio and San Andreas faults south of their junction shows the crust between them to have formed shallow extensional basins that are dissected by parallel strike‐slip faults. We employ a regional finite element...
Authors
Tom Parsons, Terry R. Bruns, Ray W. Sliter
Non-USGS Publications**
1992, by Parsons, T. et al., Department of Geophysics, Stanford University
1992, by Parsons, T., et al., Department of Geophysics, Stanford University
1991, by Howie, J.M., et al., Department of Geophysics, Stanford University
1991, by Parsons, T., and Thompson, G.A., Department of Geophysics, Stanford University
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government