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, Menlo Park, 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-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-present
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
The predictive skills of elastic Coulomb rate-and-state aftershock forecasts during the 2019 Ridgecrest, California, earthquake sequence
Submarine landslide kinematics derived from high-resolution imaging in Port Valdez, Alaska
The role of seismic and slow slip events in triggering the 2018 M7.1 Anchorage earthquake in the Southcentral Alaska subduction zone
A new technique to calculate earthquake stress transfer and to forecast aftershocks
A combinatorial approach to determine earthquake magnitude distributions on a variable slip-rate fault
Characteristic earthquake magnitude frequency distributions on faults calculated from consensus data in California
Determining on-fault earthquake magnitude distributions from integer programming
Testing earthquake links in Mexico from 1978 up to the 2017 M=8.1 Chiapas and M=7.1 Puebla shocks
Probabilistic tsunami hazard analysis: Multiple sources and global applications
From coseismic offsets to fault-block mountains
A synoptic view of the Third Uniform California Earthquake Rupture Forecast (UCERF3)
Nucleation speed limit on remote fluid induced earthquakes
Non-USGS Publications**
**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
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Filter Total Items: 116
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 skills whenAuthorsSimone Mancini, Margarita Segou, Maximillian J Werner, Thomas E. ParsonsSubmarine 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 process. WAuthorsEmily Roland, Peter J. Haeussler, Thomas E. Parsons, Patrick E. HartThe 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, and theAuthorsMargarita Segou, Thomas E. ParsonsA 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 optimal faultAuthorsMargarita Segou, Thomas E. ParsonsA 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 feasibleAuthorsEric L. Geist, Thomas E. ParsonsCharacteristic 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 Rupture FoAuthorsThomas E. Parsons, Eric L. Geist, Rodolfo Console, Roberto CarluccioDetermining 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 can occurAuthorsEric L. Geist, Thomas E. ParsonsTesting 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 a randomiAuthorsMargarita Segou, Thomas E. ParsonsProbabilistic tsunami hazard analysis: Multiple sources and global applications
Applying probabilistic methods to infrequent but devastating natural events is intrinsically challenging. For tsunami analyses, a suite of geophysical assessments should be in principle evaluated because of the different causes generating tsunamis (earthquakes, landslides, volcanic activity, meteorological events, and asteroid impacts) with varying mean recurrence rates. Probabilistic Tsunami HazaAuthorsAnita Grezio, Andrey Babeyko, Maria Ana Baptista, Jörn Behrens, Antonio Costa, Gareth Davies, Eric L. Geist, Sylfest Glimsdal, Frank I. González, Jonathan Griffin, Carl B. Harbitz, Randall J. LeVeque, Stefano Lorito, Finn Løvholt, Rachid Omira, Christof Mueller, Raphaël Paris, Thomas E. Parsons, Jascha Polet, William Power, Jacopo Selva, Mathilde B. Sørensen, Hong Kie ThioFrom coseismic offsets to fault-block mountains
In the Basin and Range extensional province of the western United States, coseismic offsets, under the influence of gravity, display predominantly subsidence of the basin side (fault hanging wall), with comparatively little or no uplift of the mountainside (fault footwall). A few decades later, geodetic measurements [GPS and interferometric synthetic aperture radar (InSAR)] show broad (∼100 km) asAuthorsGeorge A. Thompson, Thomas E. ParsonsA synoptic view of the Third Uniform California Earthquake Rupture Forecast (UCERF3)
Probabilistic forecasting of earthquake‐producing fault ruptures informs all major decisions aimed at reducing seismic risk and improving earthquake resilience. Earthquake forecasting models rely on two scales of hazard evolution: long‐term (decades to centuries) probabilities of fault rupture, constrained by stress renewal statistics, and short‐term (hours to years) probabilities of distributed sAuthorsEdward H. Field, Thomas H. Jordan, Morgan T. Page, Kevin R. Milner, Bruce E. Shaw, Timothy E. Dawson, Glenn Biasi, Thomas E. Parsons, Jeanne L. Hardebeck, Andrew J. Michael, Ray J. Weldon, Peter M. Powers, Kaj M. Johnson, Yuehua Zeng, Peter Bird, Karen Felzer, Nicholas van der Elst, Christopher Madden, Ramon Arrowsmith, Maximillan J. Werner, Wayne R. ThatcherNucleation speed limit on remote fluid induced earthquakes
Earthquakes triggered by other remote seismic events are explained as a response to long-traveling seismic waves that temporarily stress the crust. However, delays of hours or days after seismic waves pass through are reported by several studies, which are difficult to reconcile with the transient stresses imparted by seismic waves. We show that these delays are proportional to magnitude and thatAuthorsThomas E. Parsons, Aybige Akinci, Luca MaligniniNon-USGS Publications**
1992, by Parsons, T. et al., Department of Geophysics, Stanford University1992, by Parsons, T., et al., Department of Geophysics, Stanford University1991, by Howie, J.M., et al., Department of Geophysics, Stanford University1991, 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.
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*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