Geologists examine cores on Sitkinak Island, Alaska.
Rich Briggs
My work focuses on the geology and seismotectonics of large earthquakes, with the goal of understanding how, where, and why they happen.
Research Focus
I characterize active faults for seismic hazard analysis. This requires grappling with structures and processes that control earthquakes. I also work with the USGS National Earthquake Information Center (NEIC) to respond to large earthquakes by conducting rapid field studies and analyzing remote sensing products.
Professional Preparation
BS, Geologic and Environmental Science, Stanford University, 1999
PhD, Geology, Center for Neotectonic Studies, University of Nevada, Reno, 2004
Postdoctoral Scholar, Tectonics Observatory, California Institute of Technology, 2005-2008
Professional Experience
Research Geologist, U.S. Geological Survey, Golden, CO, 2008-present
Geologist, Synergetics Incorporated, Fort Collins, CO (contracted to USGS), 2008
Science and Products
Geologic Cracks Record Earthquakes on the Reelfoot Fault in Central U.S.
Untangling Faults at Depth – What Lies Beneath Panamint Valley, California?
How Big and How Frequent Are Earthquakes on the Wasatch Fault?
Datasets documenting late Pleistocene faulting in the Pondosa fault zone, Pit River Region, Northeastern California
Earthquake geology inputs for the National Seismic Hazard Model (NSHM) 2023 (central and eastern United States), version 1.0
Datasets documenting limited evidence of Late Pleistocene tectonic surface deformation in the Eastern Tennessee Seismic Zone, Tennessee, USA
Earthquake geology inputs for the National Seismic Hazard Model (NSHM) 2025 (Puerto Rico and U.S. Virgin Islands), version 1.0
Datasets documenting neotectonic mapping of Puerto Rico
Data Release for the 2023 U.S. 50-State National Seismic Hazard Model - Overview
Earthquake geology inputs for the U.S. National Seismic Hazard Model (NSHM) 2023 (western U.S.) (ver. 3.0, December 2023)
Fault Rupture Mapping of the 6 February 2023 Kahramanmaraş, Türkiye, Earthquake Sequence from Satellite Data (ver. 1.1, February 2024)
Western U.S. geologic deformation model for use in the U.S. National Seismic Hazard Model 2023, version 1.0
Data to accompany the study Quick and dirty (and accurate) 3D paleoseismic trench models using coded scale bars
Data to accompany the study Quaternary Reelfoot fault deformation in the Obion River valley, Tennessee, USA by Delano et al. (2021)
Strike-slip in transtension: Complex crustal architecture of the Warm Springs Valley fault zone, northern Walker Lane
Geologists examine cores on Sitkinak Island, Alaska.
Geologists examine an exposure of a tidal marsh bank on Sitkinak Island, Alaska. The bank exposes interbedded peat and silt that records sudden vertical land movements associated with megathrust fault slip during large earthquakes.
Geologists examine an exposure of a tidal marsh bank on Sitkinak Island, Alaska. The bank exposes interbedded peat and silt that records sudden vertical land movements associated with megathrust fault slip during large earthquakes.
Geologists extract a hand-driven core from 2-3 m depth on Sitkinak Island, Alaska. The cores contain peat with interbedded sand layers that record inundation of the coast by prehistoric tsunamis. (l-r: Peter Haeussler, USGS; Andrew Kemp, Tufts University; Alan Nelson, USGS)
Geologists extract a hand-driven core from 2-3 m depth on Sitkinak Island, Alaska. The cores contain peat with interbedded sand layers that record inundation of the coast by prehistoric tsunamis. (l-r: Peter Haeussler, USGS; Andrew Kemp, Tufts University; Alan Nelson, USGS)
Geologists driving a core into marsh sediment to document interbedded peat and silt that records sudden vertical land movements associated with megathrust fault slip during large earthquakes.
Geologists driving a core into marsh sediment to document interbedded peat and silt that records sudden vertical land movements associated with megathrust fault slip during large earthquakes.
A tidal marsh bank exposed during low tide on Sitkinak Island, Alaska. The bank reveals ledges of alternating peat and silt. Abrupt uplift and subsidence during large megathrust earthquakes is interpreted to be the cause of the alternating layers.
A tidal marsh bank exposed during low tide on Sitkinak Island, Alaska. The bank reveals ledges of alternating peat and silt. Abrupt uplift and subsidence during large megathrust earthquakes is interpreted to be the cause of the alternating layers.
Base camp, Sitkinak Island.
Base camp, Sitkinak Island.
The 2023 US 50-State National Seismic Hazard Model: Overview and implications
The USGS 2023 Conterminous U.S. time‐independent earthquake rupture forecast
We present the 2023 U.S. Geological Survey time‐independent earthquake rupture forecast for the conterminous United States, which gives authoritative estimates of the magnitude, location, and time‐averaged frequency of potentially damaging earthquakes throughout the region. In addition to updating virtually all model components, a major focus has been to provide a better representation of epistemi
Rapid surface rupture mapping from satellite data: The 2023 Kahramanmaraş, Turkey (Türkiye), earthquake sequence
Rapid characterization of the February 2023 Kahramanmaraş, Turkey, earthquake sequence
Climatic influence on the expression of strike-slip faulting
Seismic sources in the aleutian cradle of tsunamis
Western U.S. geologic deformation model for use in the U.S. National Seismic Hazard Model 2023
Simplifying complex fault data for systems-level analysis: Earthquake geology inputs for U.S. NSHM 2023
How similar was the 1983 Mw 6.9 Borah Peak earthquake rupture to its surface-faulting predecessors along the northern Lost River fault zone (Idaho, USA)?
Changing impacts of Alaska-Aleutian subduction zone tsunamis in California under future sea-level rise
STEPS: Slip time earthquake path simulations applied to the San Andreas and Toe Jam Hill Faults to redefine geologic slip rate uncertainty
Geophysical constraints on the crustal architecture of the transtensional Warm Springs Valley fault zone, northern Walker Lane, western Nevada, USA
STEPS: Slip Time Earthquake Path Simulations applied to the San Andreas and Toe Jam Hill faults to redefine geologic slip rate uncertainty (Matlab code)
Science and Products
Geologic Cracks Record Earthquakes on the Reelfoot Fault in Central U.S.
Untangling Faults at Depth – What Lies Beneath Panamint Valley, California?
How Big and How Frequent Are Earthquakes on the Wasatch Fault?
Datasets documenting late Pleistocene faulting in the Pondosa fault zone, Pit River Region, Northeastern California
Earthquake geology inputs for the National Seismic Hazard Model (NSHM) 2023 (central and eastern United States), version 1.0
Datasets documenting limited evidence of Late Pleistocene tectonic surface deformation in the Eastern Tennessee Seismic Zone, Tennessee, USA
Earthquake geology inputs for the National Seismic Hazard Model (NSHM) 2025 (Puerto Rico and U.S. Virgin Islands), version 1.0
Datasets documenting neotectonic mapping of Puerto Rico
Data Release for the 2023 U.S. 50-State National Seismic Hazard Model - Overview
Earthquake geology inputs for the U.S. National Seismic Hazard Model (NSHM) 2023 (western U.S.) (ver. 3.0, December 2023)
Fault Rupture Mapping of the 6 February 2023 Kahramanmaraş, Türkiye, Earthquake Sequence from Satellite Data (ver. 1.1, February 2024)
Western U.S. geologic deformation model for use in the U.S. National Seismic Hazard Model 2023, version 1.0
Data to accompany the study Quick and dirty (and accurate) 3D paleoseismic trench models using coded scale bars
Data to accompany the study Quaternary Reelfoot fault deformation in the Obion River valley, Tennessee, USA by Delano et al. (2021)
Strike-slip in transtension: Complex crustal architecture of the Warm Springs Valley fault zone, northern Walker Lane
Geologists examine cores on Sitkinak Island, Alaska.
Geologists examine cores on Sitkinak Island, Alaska.
Geologists examine an exposure of a tidal marsh bank on Sitkinak Island, Alaska. The bank exposes interbedded peat and silt that records sudden vertical land movements associated with megathrust fault slip during large earthquakes.
Geologists examine an exposure of a tidal marsh bank on Sitkinak Island, Alaska. The bank exposes interbedded peat and silt that records sudden vertical land movements associated with megathrust fault slip during large earthquakes.
Geologists extract a hand-driven core from 2-3 m depth on Sitkinak Island, Alaska. The cores contain peat with interbedded sand layers that record inundation of the coast by prehistoric tsunamis. (l-r: Peter Haeussler, USGS; Andrew Kemp, Tufts University; Alan Nelson, USGS)
Geologists extract a hand-driven core from 2-3 m depth on Sitkinak Island, Alaska. The cores contain peat with interbedded sand layers that record inundation of the coast by prehistoric tsunamis. (l-r: Peter Haeussler, USGS; Andrew Kemp, Tufts University; Alan Nelson, USGS)
Geologists driving a core into marsh sediment to document interbedded peat and silt that records sudden vertical land movements associated with megathrust fault slip during large earthquakes.
Geologists driving a core into marsh sediment to document interbedded peat and silt that records sudden vertical land movements associated with megathrust fault slip during large earthquakes.
A tidal marsh bank exposed during low tide on Sitkinak Island, Alaska. The bank reveals ledges of alternating peat and silt. Abrupt uplift and subsidence during large megathrust earthquakes is interpreted to be the cause of the alternating layers.
A tidal marsh bank exposed during low tide on Sitkinak Island, Alaska. The bank reveals ledges of alternating peat and silt. Abrupt uplift and subsidence during large megathrust earthquakes is interpreted to be the cause of the alternating layers.
Base camp, Sitkinak Island.
Base camp, Sitkinak Island.
The 2023 US 50-State National Seismic Hazard Model: Overview and implications
The USGS 2023 Conterminous U.S. time‐independent earthquake rupture forecast
We present the 2023 U.S. Geological Survey time‐independent earthquake rupture forecast for the conterminous United States, which gives authoritative estimates of the magnitude, location, and time‐averaged frequency of potentially damaging earthquakes throughout the region. In addition to updating virtually all model components, a major focus has been to provide a better representation of epistemi