Tom Parsons

Science and Products

• Science
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  November 9, 2021

  Probabilistic Forecasting of Earthquakes, Tsunamis, and Earthquake Effects in the Coastal Zone

  The nation's coastlines are vulnerable to the interrelated hazards posed by earthquakes, landslides, and tsunamis. In the marine environment these events often occur in concert, and distant triggers can cause severe local effects, making the issue global in scope. As the population continues to migrate toward the coastlines, the social impacts of these hazards are expected to grow.

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  Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

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  November 9, 2021

  Probabilistic Forecasting of Earthquakes, Tsunamis, and Earthquake Effects in the Coastal Zone

  The nation's coastlines are vulnerable to the interrelated hazards posed by earthquakes, landslides, and tsunamis. In the marine environment these events often occur in concert, and distant triggers can cause severe local effects, making the issue global in scope. As the population continues to migrate toward the coastlines, the social impacts of these hazards are expected to grow.

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  October 15, 2021

  U.S. West Coast and Alaska Marine Geohazards

  Marine geohazards are sudden and extreme events beneath the ocean that threaten coastal populations. Such underwater hazards include earthquakes, volcanic eruptions, landslides, and tsunamis.

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  Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, 3-D CT Core Imaging Laboratory, Core Preparation and Analysis Laboratory and Sample Repositories

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  October 15, 2021

  U.S. West Coast and Alaska Marine Geohazards

  Marine geohazards are sudden and extreme events beneath the ocean that threaten coastal populations. Such underwater hazards include earthquakes, volcanic eruptions, landslides, and tsunamis.

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• Data
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  January 19, 2022

  Gridded Data from a 2011 Multibeam Bathymetric Survey of the Western Part of Passage Canal, Near Whittier, Alaska

  This data release provides bathymetry data for the western part of Passage Canal, near Whittier Alaska. It was collected by the USGS Pacific Coastal and Marine Science Center in 2011 under Field Activity Number A0111GA. The data release consists of a 5 m grid, derived from processed and cleaned multibeam data. Depths were corrected for tidal variations and calculated using conductivity, temperatur

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  Alaska Science Center

  April 23, 2020

  Chirp, multichannel minisparker, and boomer seismic-reflection data from USGS field activity G-01-13-GA collected in Port Valdez, Alaska, in September 2013

  Multichannel minisparker and boomer seismic-reflection and chirp sub bottom data were collected by the U.S. Geological Survey in September of 2013 in Port Valdez, Alaska. Data were collected aboard the USGS R/V Alaskan Gyre during field activity G-01-13-GA. Sub-bottom acoustic penetration spans several hundreds of meters and is variable by location. High-resolution multichannel seismic-reflection

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  Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center
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• Publications
  Filter Total Items: 112

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  TypeArticleBookBook ChapterConference PaperNewsletterOtherReportThesis

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  Year20232022202120202019201820172016201520142013201220112010200920082007200620052004200320022001200019991998199719961995

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  February 23, 2023

  Combinatorial optimization of earthquake spatial distributions under minimum cumulative stress constraints

  We determine optimal on‐fault earthquake spatial distributions using a combinatorial method that minimizes the long‐term cumulative stress resolved on the fault. An integer‐programming framework was previously developed to determine the optimal arrangement of a millennia‐scale earthquake sample that minimizes the misfit to a target slip rate determined from geodetic data. The resulting cumulative

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  Pacific Coastal and Marine Science Center

  January 11, 2023

  “Aftershock Faults” and what they could mean for seismic hazard assessment

  We study stress‐loading mechanisms for the California faults used in rupture forecasts. Stress accumulation drives earthquakes, and that accumulation mechanism governs recurrence. Most moment release in California occurs because of relative motion between the Pacific plate and the Sierra Nevada block; we calculate relative motion directions at fault centers and compare with fault displacement dire

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  Pacific Coastal and Marine Science Center

  October 31, 2022

  On the use of high-resolution and deep-learning seismic catalogs for short-term earthquake forecasts: Potential benefits and current limitations

  Enhanced earthquake catalogs provide detailed images of evolving seismic sequences. Currently, these data sets take some time to be released but will soon become available in real time. Here, we explore whether and how enhanced seismic catalogs feeding into established short-term earthquake forecasting protocols may result in higher predictive skill. We consider three enhanced catalogs for the 201

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  Pacific Coastal and Marine Science Center

  July 25, 2022

  Crustal permeability changes observed from seismic attenuation: Impacts on multi-mainshock sequences

  We use amplitude ratios from narrowband-filtered earthquake seismograms to measure variations of seismic attenuation over time, providing unique insights into the dynamic state of stress in the Earth’s crust at depth. Our dataset from earthquakes of the 2016-2017 Central Apennines sequence allows us to obtain high-resolution time histories of seismic attenuation (frequency band: 0.5-30 Hz) charact

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  Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

  March 5, 2021

  The making of the NEAM Tsunami Hazard Model 2018 (NEAMTHM18)

  The NEAM Tsunami Hazard Model 2018 (NEAMTHM18) is a probabilistic hazard model for tsunamis generated by earthquakes. It covers the coastlines of the North-eastern Atlantic, the Mediterranean, and connected seas (NEAM). NEAMTHM18 was designed as a three-phase project. The first two phases were dedicated to the model development and hazard calculations, following a formalized decision-making proces

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  Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

  January 14, 2021

  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 at, or nea

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  Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

  November 20, 2020

  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 colloids by

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  Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Earthquake Hazards Program, Pacific Coastal and Marine Science Center

  July 20, 2020

  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 hypothesize

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  Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

  July 15, 2020

  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 global

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  Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

  June 23, 2020

  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 when

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  Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

  June 10, 2020

  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 process. W

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  Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Alaska Science Center, Pacific Coastal and Marine Science Center

  April 23, 2020

  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, and the

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  Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

  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.

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  March 23, 2023

  New Wave Glider will study Earthquake Processes along U.S. Subduction Zones

  The USGS has acquired a new state-of-the-art wave glider for constraining plate motions and earthquake processes along U.S. subduction zones.

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  March 9, 2021

  Unlocking plate motions of the Cascadia subduction zone with seafloor geodesy

  Seeking understanding of the fundamental constraints on plate motions, rates of convergence, and shallow strain accumulation across one of the United...

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