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Thomas Parsons

Research Geophysicist

Contact Info

Short Biography

Research Geophysicist

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.


(1) Coastal and Marine Catastrophic Hazards

(2) Working Group on California Earthquake Probabilities (WGCEP)

(3) Editor, Journal of Geophysical Research, Solid Earth

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Parsons, T., M. Segou, and W. Marzocchi (2014), Invited Review: The global aftershock zone, Tectonophysics, v. 618, p. 1-34, doi: 10.1016/j.tecto.2014.01.038 [Link]

Haeussler, P. J., T. Parsons, D. Finlayson, P. Hart, J. Chaytor, H. Ryan, H. Lee, K. Labay, A. Peterson, and L. Liberty (2014), New Imaging Of Submarine Landslides From The 1964 Earthquake Near Whittier, Alaska, And A Comparison To Failures In Other Alaskan Fjords, in Submarine Mass Movements and Their Consequences, Advances in Natural and Technological Hazards Research, v. 37, p 361-370. [Download File]

Parsons, T., and M. Segou (2014), Stress, distance, magnitude, and clustering influences on the success or failure of an aftershock forecast: the 2013 M=6.6 Lushan Earthquake and other examples, Seismological Research Letters, 85, 44-51, doi: 10.1785/0220130100 [Download File]

Geist, E. L., and T. Parsons (2014), Undersampling power law size distributions: Effect on the assessment of extreme natural hazards, Natural Hazards, DOI 10.1007/s11069-013-1024-0. [Download File]

Field, E. H., G. P. Biasi, P. Bird, T. E. Dawson, K. R. Felzer, D. D. Jackson, K. M. Johnson, T. H. Jordan, C. Madden, A. J. Michael, K. R. Milner, M. T. Page, T. Parsons, P. M. Powers, B. E. Shaw, W. R. Thatcher, R. J. Weldon, and Y. Zeng (2013), Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3)—The time-independent model, USGS Open-File Report, v. 2013–1165, CGS Special Report, v. 228, and Southern California Earthquake Center Publication, v. 1792, 114 pp., [Link]

Segou, M., T. Parsons, and W. Ellsworth (2013), Comparative evaluation of physics-based and statistical forecasts in Northern California, J. Geophys. Res. Solid Earth, 118, doi:10.1002/2013JB010313. [Link]

Geist, E. L., J. D. Chaytor, T. Parsons, and U. ten Brink (2013), Estimation of submarine mass failure probability from a sequence of dateable deposits, Geosphere, v. 9, 287-298, doi:10.1130/GES00829.1 [Download File]

Milner, K. R., M. T. Page, E. H. Field, T. Parsons, G. P. Biasi, and B. E. Shaw (2013), Appendix T—Defining the Inversion Rupture Set Using Plausibility Filters, USGS Open-File Report, v. 2013–1165, 14 pp. [Download File]

Biasi, G., T. Parsons, R. J. Weldon II, and T. E. Dawson (2013), Appendix J— fault-to-fault rupture probabilities, USGS Open-File Report, v. 2013–1165, 20 pp., [Download File]

Parsons, T., K. M. Johnson, P. Bird, J.M. Bormann, T.E. Dawson, E.H. Field, W.C. Hammond, T.A. Herring, R. McCaffrey, Z.-K. Shen, W.R. Thatcher, R.J. Weldon II, and Y. Zeng (2013), Appendix C—Deformation models for UCERF3, USGS Open-File Report, v. 2013–1165, 66 pp., [Download File]

Parsons, T., Y. Ogata, J. Zhuang, and E. L. Geist (2012), Evaluation of static stress change forecasting with prospective and blind tests, Geophysical Journal International, v. 188, 1425–1440, doi: 10.1111/j.1365-246X.2011.05343.x. [Download File]

Parsons, T., J. O. Kaven, A. A. Velasco, and H. Gonzalez-Huizar (2012), Unraveling the apparent magnitude threshold of remote earthquake triggering using full wave-field surface wave simulation, Geochemistry Geophysics Geosystems (G3), v. 13, doi: 10.1029/2012GC004164. [Download File]

Parsons, T. (2012), Paleoseismic interevent times interpreted for an unsegmented earthquake rupture forecast, Geophysical Research Letters, v. 39, doi:10.1029/2012GL052275. [Download File]

Parsons, T., and E. L. Geist (2012) Were global M≥8.3 earthquake time intervals random between 1900-2011?, Bulletin of the Seismological Society of America, v. 102, p. 1583-1592, doi:10.1785/01201100282. [Download File]

Parsons, T., R. Console, G. Falcone, M. Murru, and K. Yamashina (2012), Comparison of characteristic and Gutenberg-Richter models for time-dependent M≥7.9 earthquake probability in the Nankai-Tokai subduction zone, Japan, Geophysical Journal International, v. 190, p. 1673-1688, doi: 10.1111/j.1365-246X.2012.05595.x [Download File]

Parsons, T., E. H. Field, M. T. Page, and K. Milner (2012), Earthquake rupture connections on mapped California faults ranked by calculated static linking stresses, Bulletin of the Seismological Society of America, v. 102, p. 2677-2676, doi: 10.1785/0120100349. [Download File]

Parsons, T., and A. A. Velasco (2011), Absence of remotely triggered large earthquakes beyond the main shock region, Nature Geoscience, v. 4, p. 312–316, doi:10.1038/ngeo1110. [Download File]

Parsons, T. and W. Thatcher (2011), Diffuse Pacific - North American plate boundary: 1000 km of dextral shear inferred from modeling GPS data, Geology, v. 39, p. 943–946; doi:10.1130/G32176. [Download File]

Geist, E. L., and T. Parsons (2011), Assessing historical rate changes in global tsunami occurrence, Geophysical Journal International, v. 187, p. 497–509, doi: 10.1111/j.1365-246X.2011.05160.x [Download File]

Parsons, T. (2011), No correlation between Anderson Reservoir stage level and underlying Calaveras fault seismicity despite calculated differential stress increases, Lithosphere, 3, p. 261-264, doi:10.1130/L148.1 [Download File]

Geist, E. L., and T. Parsons (2010), Estimating the empirical probability of submarine landslide occurrence, International Symposium on Submarine Mass Movements and their Consequences, Book Series: Advances in Natural and Technological Hazards Research, v. 28, Submarine Mass Movements and Their Consequences, Springer, DOI 10.1007/978-90-481-3071-9, p. 377-386. [Download File]

Oppenheimer, D., W. Bakun, T. Parsons, R. Simpson, J. Boatwright, R. Uhrhammer (2010), The 2007 M5.4 Alum Rock Earthquake: Implications for Future Earthquakes on the Central and Southern Calaveras Fault, Journal of Geophysical Research, v. 115, doi:10.1029/2009JB006683. [Download File]

Parsons, T. (2010), Earthquake probability calculated from paleoseismic observations on the south Hayward fault, in Knudsen, K., Baldwin, J., Brocher, T. Burgmann, R., Craig, M., Cushing, D., Hellwig, P., Wiegers, M., and Wong, I., eds., Proceedings of the Third Conference on Earthquake Hazards in the Eastern San Francisco Bay Area, California Geological Survey Special Report 219, p. 179-183. [Download File]

Geist, E. L., T. Parsons, U.S. ten Brink, and H. J. Lee (2009), Chapter 4: Tsunami Probability, in The Sea: Volume 15 (Tsunamis), edited by A. R. Robinson and E. N. Bernard, Harvard University Press, Boston, MA, p. 93-135, ISBN 978-0-674-03173-9 [Download File]

Geist, E. L., and T. Parsons (2009), Assessment of source probabilities for potential tsunamis affecting the U.S. Atlantic coast, Marine Geology, v. 264, p. 98-108, DOI: 10.1016/j.margeo.2008.08.005. [Download File]

Ganas, A., and T. Parsons (2009), 3-D model of Hellenic Arc deformation and origin of the Cretan uplift, Journal of Geophysical Research, v. 114, doi:10.1029/2008JB005599. [Download File]

Parsons, T., and E. L. Geist (2009), Is there basis for preferring characteristic earthquakes over Gutenberg-Richter distributions on individual faults in probabilistic earthquake forecasting?, Bulletin of the Seismological Society of America, v. 99, p. 2012–2019, doi: 10.1785/0120080069 [Download File]

Field, E. H., T. E. Dawson, K. R. Felzer, A. D. Frankel, V. Gupta, T. H. Jordan, T. Parsons, M. D. Petersen, R. S. Stein, R. J. Weldon II, and C. J. Wills (2009), The uniform California earthquake rupture forecast, version 2 (UCERF 2), Bulletin of the Seismological Society of America, v. 99, p. 2053-2107, doi: 10.1785/0120080049. [Download File]

Thompson, G. A., and T. Parsons (2009), Can footwall unloading explain late Cenozoic uplift of the Sierra Nevada crest?, International Geology Review, v. 51, p. 986-993, doi:10.1080/00206810903059156. [Download File]

Nowack, R. L., T. Parsons, and A. Revil (2009), Editorial: Exploring New Frontiers with JGR-Solid Earth, Journal of Geophysical Research, v. 114, doi:10.1029/2009JB006977. [Download File]

Parsons, T., and A. A. Velasco (2009), On near-source earthquake triggering, Journal of Geophysical Research, v. 114, doi:10.1029/2008JB006277. [Download File]

Parsons, T. (2009), Lasting earthquake legacy, Nature, v. 462, p. 41-42. [Download File]

Gonzalez, F., E. Geist, C. E. Synolakis, D. Arcas, D. Bellomo, D. Carlton, T. Horning, B. Jaffe, J. Johnson, H. Mofjeld, J. Newman, T. Parsons, R. Peters, C. Peterson, G. Priest, V. V. Titov, A. Venturato, J. Weber, F. Wong, A. Yalciner (2009), Seaside, Oregon probabilistic tsunami hazard assessment, Journal of Geophysical Research, v. 114, doi:10.1029/2008JC005132. [Download File]

Parsons, T. (2008), Persistent earthquake clusters and gaps from slip on irregular faults, Nature Geoscience, v. 1, p. 59-63, doi:10.1038/ngeo.2007.36 [Download File]

Geist, E. L., and T. Parsons (2008), Distribution of tsunami inter-event times, Geophysical Research Letters, v. 35, doi:10.1029/2007GL032690 [Download File]

Velasco, A. A., S. Hernandez, T. Parsons, and K. Pankow (2008), Global ubiquity of dynamic earthquake triggering, Nature Geoscience, v. 1, p. 375-379, doi:10.1038/ngeo204. [Download File]

Parsons, T. (2008), Monte Carlo method for determining earthquake recurrence parameters from short paleoseismic catalogs: Example calculations for California, Journal of Geophysical Research, v. 113, doi:10.1029/2007JB004998 [Download File]

Parsons, T., C. Ji, and E. Kirby (2008), Stress changes from the 2008 Wenchuan earthquake and increased hazard in the Sichuan basin, Nature, v. 454, p. 509-510, doi:10.1038/nature07177. [Download File]

Ryan, H., T. Parsons, and R. Sliter (2008), Vertical tectonic deformation associated with the San Andreas fault zone offshore of San Francisco, California, Tectonophysics, v. 457, p. 209-223, doi:10.1016/j.tecto.2008.06.011 [Download File]

Mallman, E. P., and T. Parsons (2008), A Global Search for Stress Shadows, Journal of Geophysical Research, v. 113, doi:10.1029/2007JB005336. [Download File]

Parsons, T. (2008), Earthquake recurrence on the south Hayward fault is most consistent with a time dependent, renewal process, Geophysical Research Letters, v. 36, doi:10.1029/2008GL035887 [Download File]

Parsons, T., and E. L. Geist (2008), Tsunami probability in the Caribbean region, Pure and Applied Geophysics, v. 165, p. 2089–2116, DOI 10.1007/s00024-008-0416-7 [Download File]

Parsons, T. (2007), Forecast experiment: Do temporal and spatial b-value variations along the Calaveras fault portend M≥4.0 earthquakes?, Journal of Geophysical Research, v. 112, doi:10.1029/2006JB004632 [Download File]

Mikhailov, V. O., T. Parsons, R. W. Simpson, E. P. Timoshkina, and C. Williams (2007), Why the Sacramento Delta Area Differs from Other Parts of the Great Valley: Numerical Modeling of Thermal Structure and Thermal Subsidence of Forearc Basins, Izvestiya, Physics of the Solid Earth, v. 43, p. 75–90. [Download File]

Parsons, T. (2006), Tectonic stressing in California modeled from GPS observations, Journal of Geophysical Research, v. 111, doi:10.1029/2005JB003946 [Download File]

Geist, E. L., and T. Parsons (2006), Probabilistic analysis of tsunami hazards, Natural Hazards, v. 37, p. 277–314, DOI 10.1007/s11069-005-4646-z. [Download File]

Stein, R. S., S. Toda, T. Parsons, and E. Grunewald (2006), A new probabilistic seismic hazard assessment for greater Tokyo, Proceedings of the Royal Society of London A, v. 364, p. 1965–1988, doi:10.1098/rsta.2006.1808 [Download File]

Parsons, T., R. S. Yeats, Y. Yagi, and A. Hussain (2006), Static stress change from the 8 October, 2005 M=7.6 Kashmir earthquake, Geophysical Research Letters, v. 33, doi:10.1029/2005GL025429 [Download File]

Parsons, T., G. A. Thompson, A. H. Cogbill (2006), Earthquake and volcano clustering via stress transfer at Yucca Mountain, Nevada, Geology, v. 34, p. 785–788, doi: 10.1130/G22636.1 [Download File]

Parsons, T. (2006), M≥7.0 earthquake recurrence on the San Andreas fault from a stress renewal model, Journal of Geophysical Research, v. 111, doi:10.1029/2006JB004415. [Download File]

Parsons, T., T. R. Bruns, R. Sliter (2005), Structure and mechanics of the San Gregorio-San Andreas fault junction, Geochemistry Geophysics Geosystems (G3), v. 6, doi:10.1029/2004GC000838. [Download File]

Parsons, T. (2005), A hypothesis for delayed dynamic earthquake triggering, Geophysical Research Letters, v. 32, doi:10.1029/2004GL021811. [Download File]

Parsons, T. (2005), Significance of stress transfer in time-dependent earthquake probability calculations, Journal of Geophysical Research, v. 110, doi:10.1029/2004JB003190. [Download File]

Geist, E. L., and T. Parsons (2005), Triggering of tsunamigenic aftershocks from large strike-slip earthquakes: analysis of the November 2000 New Ireland earthquake sequence, Geochemistry Geophysics Geosystems (G3), v. 6, doi:10.1029/2005GC000935 [Download File]

Parsons, T. (2004), Recalculated probability of M≥7 earthquakes beneath the Sea of Marmara, Turkey, Journal of Geophysical Research, 109, doi:10.1029/2001JB002667. [Download File]

Brocher, T. M., T. Parsons, A. M. Tréhu, R. S. Crosson, C. M. Snelson, and M. A. Fisher (2003), Seismic evidence for widespread serpentinized forearc upper mantle along the Cascadia Margin: Geology, v. 31, p. 267–270. [Download File]

Parsons, T., R. Sliter, E. L. Geist, R. C. Jachens, B. E. Jaffe, A. Foxgrover, P. E. Hart, and J. McCarthy (2003), Structure and mechanics of the Hayward-Rodgers Creek fault stepover, San Francisco Bay, California, Bulletin of the Seismological Society of America, v. 93, p. 2187-2200. [Download File]

Parsons, T. (2002), Post-1906 stress recovery of the San Andreas fault system from 3-D finite element analysis, Journal of Geophysical Research, 107, 2162, doi:10.1029/2001JB001051 [Download File]

ten Brink, U. S., P. C. Molzer, M. A. Fisher, R. J. Blakely, R. C. Bucknam, T. Parsons, R. S. Crosson, and K. C. Creager (2002), Subsurface geometry and evolution of the Seattle Fault Zone and the Seattle Basin, Washington, Bulletin of the Seismological Society of America, 92, 1737-1753. [Download File]

Parsons, T. (2002), Global Omori law decay of triggered earthquakes: Large aftershocks outside the classical aftershock zone, Journal of Geophysical Research, 107, 2199, doi:10.1029/2001JB000646 [Download File]

Parsons, T. (2002), Nearly frictionless faulting from unclamping in long-term interaction models, Geology, v. 30, p. 1063-1066. [Download File]

Parsons, T., J. McCarthy, and G. A. Thompson (2001), Very different crustal response to extreme extension in the southern Basin and Range and Colorado Plateau transition, in, Erskine, M. C., Faulds, J. E., Bartley, J. M., and Rowley, P. D., editors, American Association of Petroleum Geologists Pacific Section Guidebook, GB 78, p. 291-304. [Download File]

Parsons, T., R. J. Blakely, and T. M. Brocher (2001), A simple algorithm for sequentially incorporating gravity observations in seismic traveltime tomography, International Geology Review, 43, 1073-1086. [Download File]

Parsons, T., S. Toda, R. S. Stein, A. Barka, and J. H. Dieterich (2000), Heightened odds of large earthquakes near Istanbul: an interaction-based probability calculation, Science, v. 288, p. 661-665 [Download File]

Hole, J. A., T. M. Brocher, S. L. Klemperer, T. Parsons, H. M. Benz, and K. P. Furlong (2000), Three-dimensional seismic velocity structure of the San Francisco Bay area, Journal of Geophysical Research, v. 105, p. 13859-13874. [Download File]

Parsons, T., and D. Dreger (2000), Static-stress impact of the 1992 Landers earthquake sequence on nucleation and slip at the site of the 1999 M=7.1 Hector Mine earthquake, southern California, Geophysical Research Letters, v. 27, p. 1949-1952. [Download File]

Parsons, T., R. E. Wells, E. Flueh, U. S. ten Brink, and M. A. Fisher (1999), Three-dimensional velocity structure of Siletzia and other accreted terranes in the Cascadia fore arc of Washington, Journal of Geophysical Research, v. 104, p. 18015-18039 [Download File]

Parsons, T., and P. E. Hart (1999), Dipping San Andreas and Hayward faults revealed beneath San Francisco Bay, California, Geology, v. 27, p. 839-842. [Download File]

Parsons, T., R. S. Stein, R. W. Simpson, and P. A. Reasenberg (1999), Stress sensitivity of fault seismicity: a comparison between limited-offset oblique and major strike-slip faults, Journal of Geophysical Research, v. 104, p. 20183-20202. [Download File]

Fisher, M. A., E. R. Flueh, D.W. Scholl, T. Parsons, R. E. Wells, A. Trehu, U. ten Brink, and C. S. Weaver (1999), Geologic processes of accretion: Cascadia subduction zone west of Washington State, Journal of Geodynamics, v. 27, p. 277-288. [Download File]

Parsons, T. (1998), Seismic-reflection evidence that the Hayward fault extends into the lower crust of the San Francisco Bay area, California, Bulletin of the Seismological Society of America, v. 88, 1212-1223 [Download File]

Flueh, E., M. A. Fisher, J. Bialas, J. R. Childs, D. Klaeschen, N. Kukowski, T. Parsons, D. W. Scholl, U. ten Brink, A. M. Trehu, and N. Vidal (1998), New seismic images of the Cascadia subduction zone from Cruise SO108- ORWELL, Tectonophysics, v. 293, 69-84. [Download File]

Parsons, T., G. A. Thompson, and R. P. Smith (1998), More than one way to stretch: A tectonic model for extension along the plume track of the Yellowstone hotspot and adjacent Basin and Range Province, Tectonics, 17, p. 221-234. [Download File]

Parsons, T., A. M. Trehu, J. H. Luetgert, K. Miller, F. Killbride, R. E. Wells, M. A. Fisher, E. Flueh, U. S. ten Brink, and N. I. Christensen (1998), A new view into the Cascadia subduction zone and volcanic arc: Implications for earthquake hazards along the Washington margin, Geology, v. 26, p. 199-201. [Download File]

Parsons, T., and M. L. Zoback (1997), Three-dimensional upper crustal velocity structure beneath San Francisco Peninsula, California, Journal of Geophysical Research, v. 102, p. 5473-5490. [Download File]

Parsons, T., and J. McCarthy (1996), Crustal and upper mantle velocity structure of the Salton Trough, southeast California, Tectonics, v. 15, p. 456-471. [Download File]

Parsons, T., J. McCarthy, W. M. Kohler, C. J. Ammon, H. M. Benz, J. A. Hole, and E. E. Criley (1996), The crustal structure of the Colorado Plateau, Arizona: Application of new long-offset seismic data analysis techniques, Journal of Geophysical Research, v. 101, p. 11173-11194. [Download File]

Bohannon, R. G., and Parsons, T. (1995), Tectonic implications of post-30 Ma Pacific and North American relative plate motions, Geological Society of America Bulletin, v. 107, p. 937-959. [Download File]

Parsons, T., Christensen, N. I., and Wilshire, H. G. (1995), Velocities of southern Basin and Range xenoliths: Insights on the nature of lower crustal reflectivity and composition, Geology, v. 23, p. 129-132. [Download File]

Parsons, T. (1995), The Basin and Range Province, in Continental Rifts: Evolution, Structure and Tectonics, Olsen, K., ed., Amsterdam, Elsevier, ISBN 044489-566-3, p. 277-324. [Download File]

Parsons, T., and McCarthy, J. (1995), The active southwest margin of the Colorado Plateau: Uplift of mantle origin: Geological Society of America Bulletin, v. 107, p. 139-147. [Download File]

McCarthy, J., and Parsons, T. (1994), Insights into the kinematic Cenozoic evolution of the Basin and Range-Colorado Plateau transition from coincident seismic refraction and reflection data, Geological Society of America Bulletin, v. 106, p. 747-759 [Download File]

Parsons, T., Thompson, G. A., and Sleep, N. H. (1994), Mantle plume influence on the Neogene uplift and extension of the U.S. western Cordillera? Geology, v. 23, p. 83-86 [Download File]

Parsons, T., and Thompson, G. A. (1993), Does magmatism influence low-angle normal faulting? Geology, v. 21, p. 247-250 [Download File]

Parsons, T., Sleep, N. H., and Thompson, G. A. (1992), Host rock rheology controls on the emplacement of tabular intrusions: Implications for underplating of continental crust: Tectonics, v. 11, p. 1348-1356 [Download File]

Parsons, T., Howie, J. M., and Thompson, G. A. (1992), Seismic constraints on the nature of lower crustal reflectors beneath the extending southern transition zone of the Colorado Plateau, Arizona, Journal of Geophysical Research, v. 97, p. 12391-12407 [Download File]

Howie, J. M., Parsons, T., and Thompson, G. A. (1991), High-resolution P- and S-wave deep crustal imaging across the edge of the Colorado Plateau, USA: Increased reflectivity caused by initiating extension: in Continental Lithosphere: Deep Seismic Reflections, Volume 22, Meissner, R. et al., eds., Washington D.C., American Geophysical Union, Geodynamics Series, ISBN 087590-522-6, p. 21-29

Parsons, T., and Thompson, G. A. (1991), The role of magma overpressure in suppressing earthquakes and topography: Worldwide examples: Science, v. 253, p. 1399-1402. [Download File]


My Science Topics

Science Topic
Natural Hazardsearthquake occurrences
Natural Hazardsearthquake probabilities
Natural Hazardsearthquakes
Natural Hazardstsunamis

My USGS Science Strategy Areas

A National Hazard, Risk, and Resilience Assessment Program

Forecasting Earthquakes and Tsunamis

Image of Current Focus for Forecasting Earthquakes and Tsunamis

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Contact Information

Thomas Parsons
345 Middlefield Road
Menlo Park, CA 94025-3561
650-329-5299 - Fax
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