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
The weight of cities: Urbanization effects on Earth’s subsurface The weight of cities: Urbanization effects on Earth’s subsurface
Across the world, people increasingly choose to live in cities. By 2050, 70% of Earth's population will live in large urban areas. Upon considering a large city, questions arise such as, how much does that weigh? What are its effects on the landscape? Does it cause measurable subsidence? Here I calculate the weight of San Francisco Bay region urbanization, where 7.75 million people live...
Authors
Thomas E. Parsons
Seismic attenuation monitoring of a critically stressed San Andreas fault Seismic attenuation monitoring of a critically stressed San Andreas fault
We show that seismic attenuation ( ) along the San Andreas fault (SAF) at Parkfield correlates with the occurrence of moderate‐to‐large earthquakes at local and regional distances. Earthquake‐related anomalies are likely caused by changes in permeability from dilatant static stress changes, damage by strong shaking from local sources, and pore unclogging/clogging from mobilization of...
Authors
Luca Malagnini, Thomas E. Parsons
On the use of receiver operating character tests for evaluating spatial earthquake forecasts On the use of receiver operating character tests for evaluating spatial earthquake forecasts
Spatial forecasts of triggered earthquake distributions have been ranked using receiver operating characteristic (ROC) tests. The test is a binary comparison between regions of positive and negative forecast against positive and negative presence of earthquakes. Forecasts predicting only positive changes score higher than Coulomb methods, which predict positive and negative changes. I...
Authors
Thomas E. Parsons
Distribution of earthquakes on a branching fault system using integer programming and greedy sequential methods Distribution of earthquakes on a branching fault system using integer programming and greedy sequential methods
A new global optimization method is used to determine the distribution of earthquakes on a complex, connected fault system. The method, integer programming, has been advanced in the field of operations research, but has not been widely applied to geophysical problems until recently. In this application, we determine the optimal distribution of earthquakes on mapped faults to minimize the...
Authors
Eric L. Geist, Thomas E. Parsons
The predictive skills of elastic Coulomb rate-and-state aftershock forecasts during the 2019 Ridgecrest, California, earthquake sequence The predictive skills of elastic Coulomb rate-and-state aftershock forecasts during the 2019 Ridgecrest, California, earthquake sequence
Operational earthquake forecasting protocols commonly use statistical models for their recognized ease of implementation and robustness in describing the short-term spatiotemporal patterns of triggered seismicity. However, recent advances on physics-based aftershock forecasting reveal comparable performance to the standard statistical counterparts with significantly improved predictive...
Authors
Simone Mancini, Margarita Segou, Maximillian J Werner, Thomas E. Parsons
Submarine landslide kinematics derived from high-resolution imaging in Port Valdez, Alaska Submarine landslide kinematics derived from high-resolution imaging in Port Valdez, Alaska
Submarine landslides caused by strong ground shaking during the M9.2 1964 Great Alaska earthquake generated a tsunami that destroyed much of the old town of Valdez, Alaska, and was responsible for 32 deaths at that location. We explore structural details of the 1964 landslide deposit, as well as landslide deposits from earlier events, in order to characterize kinematics of the landslide...
Authors
Emily Roland, Peter J. Haeussler, Thomas E. Parsons, Patrick E. Hart
The role of seismic and slow slip events in triggering the 2018 M7.1 Anchorage earthquake in the Southcentral Alaska subduction zone The role of seismic and slow slip events in triggering the 2018 M7.1 Anchorage earthquake in the Southcentral Alaska subduction zone
The M 7.1 2018 Anchorage earthquake occurred in the bending part of the subducting North Pacific plate near the geometrical barrier formed by the underthrusting Yakutat terrane. We calculate the triggering potential related with stress redistribution from deformation sources including the M 9.2 1964 earthquake coseismic slip, postseismic deformation, slip from regional M > 5 earthquakes...
Authors
Margarita Segou, Thomas E. Parsons
A new technique to calculate earthquake stress transfer and to forecast aftershocks A new technique to calculate earthquake stress transfer and to forecast aftershocks
Coseismic stress changes have been the primary physical principle used to explain aftershocks and triggered earthquakes. However, this method does not adequately forecast earthquake rates and diverse rupture populations when subjected to formal testing. We show that earthquake forecasts can be impaired by assumptions made in physics-based models, such as the existence of hypothetical...
Authors
Margarita Segou, Thomas E. Parsons
A combinatorial approach to determine earthquake magnitude distributions on a variable slip-rate fault A combinatorial approach to determine earthquake magnitude distributions on a variable slip-rate fault
Combinatorial methods are used to determine the spatial distribution of earthquake magnitudes on a fault whose slip rate varies along strike. Input to the problem is a finite sample of earthquake magnitudes that span 5 kyr drawn from a truncated Pareto distribution. The primary constraints to the problem are maximum and minimum values around the target slip-rate function indicating where...
Authors
Eric L. Geist, Thomas E. Parsons
Characteristic earthquake magnitude frequency distributions on faults calculated from consensus data in California Characteristic earthquake magnitude frequency distributions on faults calculated from consensus data in California
An estimate of the expected earthquake rate at all possible magnitudes is needed for seismic hazard forecasts. Regional earthquake magnitude frequency distributions obey a negative exponential law (Gutenberg‐Richter), but it's unclear if individual faults do. We add three new methods to calculate long‐term California earthquake rupture rates to the existing Uniform California Earthquake...
Authors
Thomas E. Parsons, Eric L. Geist, Rodolfo Console, Roberto Carluccio
Determining on-fault earthquake magnitude distributions from integer programming Determining on-fault earthquake magnitude distributions from integer programming
Earthquake magnitude distributions among faults within a fault system are determined from regional seismicity and fault slip rates using binary integer programming. A synthetic earthquake catalog (i.e., list of randomly sampled magnitudes) that spans millennia is first formed, assuming that regional seismicity follows a Gutenberg-Richter relation. Each earthquake in the synthetic catalog...
Authors
Eric L. Geist, Thomas E. Parsons
Testing earthquake links in Mexico from 1978 up to the 2017 M=8.1 Chiapas and M=7.1 Puebla shocks Testing earthquake links in Mexico from 1978 up to the 2017 M=8.1 Chiapas and M=7.1 Puebla shocks
The M = 8.1 Chiapas and the M = 7.1 Puebla earthquakes occurred in the bending part of the subducting Cocos plate 11 days and ~600 km apart, a range that puts them well outside the typical aftershock zone. We find this to be a relatively common occurrence in Mexico, with 14% of M > 7.0 earthquakes since 1900 striking more than 300 km apart and within a 2 week interval, not different from...
Authors
Margarita Segou, Thomas E. Parsons
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
The weight of cities: Urbanization effects on Earth’s subsurface The weight of cities: Urbanization effects on Earth’s subsurface
Across the world, people increasingly choose to live in cities. By 2050, 70% of Earth's population will live in large urban areas. Upon considering a large city, questions arise such as, how much does that weigh? What are its effects on the landscape? Does it cause measurable subsidence? Here I calculate the weight of San Francisco Bay region urbanization, where 7.75 million people live...
Authors
Thomas E. Parsons
Seismic attenuation monitoring of a critically stressed San Andreas fault Seismic attenuation monitoring of a critically stressed San Andreas fault
We show that seismic attenuation ( ) along the San Andreas fault (SAF) at Parkfield correlates with the occurrence of moderate‐to‐large earthquakes at local and regional distances. Earthquake‐related anomalies are likely caused by changes in permeability from dilatant static stress changes, damage by strong shaking from local sources, and pore unclogging/clogging from mobilization of...
Authors
Luca Malagnini, Thomas E. Parsons
On the use of receiver operating character tests for evaluating spatial earthquake forecasts On the use of receiver operating character tests for evaluating spatial earthquake forecasts
Spatial forecasts of triggered earthquake distributions have been ranked using receiver operating characteristic (ROC) tests. The test is a binary comparison between regions of positive and negative forecast against positive and negative presence of earthquakes. Forecasts predicting only positive changes score higher than Coulomb methods, which predict positive and negative changes. I...
Authors
Thomas E. Parsons
Distribution of earthquakes on a branching fault system using integer programming and greedy sequential methods Distribution of earthquakes on a branching fault system using integer programming and greedy sequential methods
A new global optimization method is used to determine the distribution of earthquakes on a complex, connected fault system. The method, integer programming, has been advanced in the field of operations research, but has not been widely applied to geophysical problems until recently. In this application, we determine the optimal distribution of earthquakes on mapped faults to minimize the...
Authors
Eric L. Geist, Thomas E. Parsons
The predictive skills of elastic Coulomb rate-and-state aftershock forecasts during the 2019 Ridgecrest, California, earthquake sequence The predictive skills of elastic Coulomb rate-and-state aftershock forecasts during the 2019 Ridgecrest, California, earthquake sequence
Operational earthquake forecasting protocols commonly use statistical models for their recognized ease of implementation and robustness in describing the short-term spatiotemporal patterns of triggered seismicity. However, recent advances on physics-based aftershock forecasting reveal comparable performance to the standard statistical counterparts with significantly improved predictive...
Authors
Simone Mancini, Margarita Segou, Maximillian J Werner, Thomas E. Parsons
Submarine landslide kinematics derived from high-resolution imaging in Port Valdez, Alaska Submarine landslide kinematics derived from high-resolution imaging in Port Valdez, Alaska
Submarine landslides caused by strong ground shaking during the M9.2 1964 Great Alaska earthquake generated a tsunami that destroyed much of the old town of Valdez, Alaska, and was responsible for 32 deaths at that location. We explore structural details of the 1964 landslide deposit, as well as landslide deposits from earlier events, in order to characterize kinematics of the landslide...
Authors
Emily Roland, Peter J. Haeussler, Thomas E. Parsons, Patrick E. Hart
The role of seismic and slow slip events in triggering the 2018 M7.1 Anchorage earthquake in the Southcentral Alaska subduction zone The role of seismic and slow slip events in triggering the 2018 M7.1 Anchorage earthquake in the Southcentral Alaska subduction zone
The M 7.1 2018 Anchorage earthquake occurred in the bending part of the subducting North Pacific plate near the geometrical barrier formed by the underthrusting Yakutat terrane. We calculate the triggering potential related with stress redistribution from deformation sources including the M 9.2 1964 earthquake coseismic slip, postseismic deformation, slip from regional M > 5 earthquakes...
Authors
Margarita Segou, Thomas E. Parsons
A new technique to calculate earthquake stress transfer and to forecast aftershocks A new technique to calculate earthquake stress transfer and to forecast aftershocks
Coseismic stress changes have been the primary physical principle used to explain aftershocks and triggered earthquakes. However, this method does not adequately forecast earthquake rates and diverse rupture populations when subjected to formal testing. We show that earthquake forecasts can be impaired by assumptions made in physics-based models, such as the existence of hypothetical...
Authors
Margarita Segou, Thomas E. Parsons
A combinatorial approach to determine earthquake magnitude distributions on a variable slip-rate fault A combinatorial approach to determine earthquake magnitude distributions on a variable slip-rate fault
Combinatorial methods are used to determine the spatial distribution of earthquake magnitudes on a fault whose slip rate varies along strike. Input to the problem is a finite sample of earthquake magnitudes that span 5 kyr drawn from a truncated Pareto distribution. The primary constraints to the problem are maximum and minimum values around the target slip-rate function indicating where...
Authors
Eric L. Geist, Thomas E. Parsons
Characteristic earthquake magnitude frequency distributions on faults calculated from consensus data in California Characteristic earthquake magnitude frequency distributions on faults calculated from consensus data in California
An estimate of the expected earthquake rate at all possible magnitudes is needed for seismic hazard forecasts. Regional earthquake magnitude frequency distributions obey a negative exponential law (Gutenberg‐Richter), but it's unclear if individual faults do. We add three new methods to calculate long‐term California earthquake rupture rates to the existing Uniform California Earthquake...
Authors
Thomas E. Parsons, Eric L. Geist, Rodolfo Console, Roberto Carluccio
Determining on-fault earthquake magnitude distributions from integer programming Determining on-fault earthquake magnitude distributions from integer programming
Earthquake magnitude distributions among faults within a fault system are determined from regional seismicity and fault slip rates using binary integer programming. A synthetic earthquake catalog (i.e., list of randomly sampled magnitudes) that spans millennia is first formed, assuming that regional seismicity follows a Gutenberg-Richter relation. Each earthquake in the synthetic catalog...
Authors
Eric L. Geist, Thomas E. Parsons
Testing earthquake links in Mexico from 1978 up to the 2017 M=8.1 Chiapas and M=7.1 Puebla shocks Testing earthquake links in Mexico from 1978 up to the 2017 M=8.1 Chiapas and M=7.1 Puebla shocks
The M = 8.1 Chiapas and the M = 7.1 Puebla earthquakes occurred in the bending part of the subducting Cocos plate 11 days and ~600 km apart, a range that puts them well outside the typical aftershock zone. We find this to be a relatively common occurrence in Mexico, with 14% of M > 7.0 earthquakes since 1900 striking more than 300 km apart and within a 2 week interval, not different from...
Authors
Margarita Segou, Thomas E. Parsons
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