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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

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New Madrid seismic zone

Geologic Cracks Record Earthquakes on the Reelfoot Fault in Central U.S.

Release Date: APRIL 25, 2019 New high-resolution lidar data reveals cracks produced from strong shaking in past earthquakes in the New Madrid seismic zone.
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Natural Hazards, Earthquake Hazards
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Geologic Cracks Record Earthquakes on the Reelfoot Fault in Central U.S.

Release Date: APRIL 25, 2019 New high-resolution lidar data reveals cracks produced from strong shaking in past earthquakes in the New Madrid seismic zone.
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Trona Wildrose Road in the Panamint Valley, California, along the section of the seismic reflection survey, looking west.

Untangling Faults at Depth – What Lies Beneath Panamint Valley, California?

Release Date: APRIL 30, 2018 The eastern edge of Panamint Valley,CA has two types of faults that can be seen in the near-surface geology. 150 geophones and a seismic source will help reveal the subsurface picture.
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Natural Hazards, Earthquake Hazards
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Untangling Faults at Depth – What Lies Beneath Panamint Valley, California?

Release Date: APRIL 30, 2018 The eastern edge of Panamint Valley,CA has two types of faults that can be seen in the near-surface geology. 150 geophones and a seismic source will help reveal the subsurface picture.
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The Wasatch fault is located in central Utah and southeast Idaho, along the eastern edge of the Basin and Range Province.

How Big and How Frequent Are Earthquakes on the Wasatch Fault?

Release Date: FEBRUARY 1, 2015 Paleoseismology along the Wasatch Fault in Utah is helping to estimate the shaking risk to nearby towns.
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Natural Hazards, Earthquake Hazards
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How Big and How Frequent Are Earthquakes on the Wasatch Fault?

Release Date: FEBRUARY 1, 2015 Paleoseismology along the Wasatch Fault in Utah is helping to estimate the shaking risk to nearby towns.
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Data to accompany the study Quaternary Reelfoot fault deformation in the Obion River valley, Tennessee, USA by Delano et al. (2021)

This data release contains machine-readable files accompanying the study Quaternary Reelfoot fault deformation in the Obion River valley, Tennessee, USA published by Delano et al. (2021) in Tectonics. The data release includes grain size analyses from three auger sites (TableS1_WilsonLoop_grainsize.txt, TableS2_Lanesferry_grainsize.txt, TableS3_BiggsFarm_grainsize.txt) and unit descriptions from t
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Earthquake Hazards

Strike-slip in transtension: Complex crustal architecture of the Warm Springs Valley fault zone, northern Walker Lane

This data release contains field data for two P-wave seismic reflection profiles acquired across the Warm Springs Valley fault zone, part of the Northern Walker Lane, NV. The dataset consists of high-resolution seismic reflection field records in .segy format, shot coordinates in .csv format, and observers? logs in .pdf format. The high-resolution seismic profiles are approximately 4 km long. The
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Geologic Hazards Science Center

Compilation of offset measurements and fault data for global strike-slip faults with multiple earthquakes

This Data Release provides the compilation of offset measurement datasets and associated fault data to accompany the manuscript "Climatic influence on the expression of strike-slip faulting" by Reitman et al. In addition to a ReadMe file, it includes two tabular datasets, one code, and one text file. The datasets are a compilation of offset measurement data ("data_multiple_eq_offset
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Geologic Hazards Science Center

Earthquake geology inputs for the U.S. National Seismic Hazard Model (NSHM) 2023 (western US) (ver. 2.0, February 2022)

This Data Release contains preliminary versions of two related databases: 1) A fault sections database ('NSHM23_FSD_v2'), which depicts the geometry of faults capable of hosting independent earthquakes, and 2) An earthquake geology site information database ('NSHM23_EQGeoDB_v2'), which contains fault slip-rate constraints at points. These databases were prepared in anticipation of updates to the N
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Natural Hazards, Earthquake Hazards, Geologic Hazards Science Center

Summary of proposed changes to geologic inputs for the U.S. National Seismic Hazard Model (NSHM) 2023, version 1.0

This data release documents proposed updates to geologic inputs (faults) for the upcoming 2023 National Seismic Hazard Model (NSHM). This version (1.0) conveys differences between 2014 NSHM fault sources and those recently released in the earthquake geology inputs for the U.S. National Seismic Hazard Model (NSHM) 2023, version 1.0 data release by Hatem et al. (2021). A notable difference between t
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Earthquake Hazards, Geologic Hazards Science Center

Earthquake geology inputs for the U.S. National Seismic Hazard Model (NSHM) 2023, version 1.0

This Data Release contains preliminary versions of two related databases: 1) A fault sections database ("NSHM2023_FaultSections_v1"), which depicts the geometry of faults capable of hosting independent earthquakes, and 2) An earthquake geology site information database ("NSHM2023_EQGeoDB_v1"), which contains fault slip-rate constraints at points. These databases
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Natural Hazards, Earthquake Hazards, Geologic Hazards Science Center

Seismic reflection imaging of the low-angle Panamint normal fault system, eastern California, 2018

A fundamental question in seismic hazard analysis is whether <30?-dipping low-angle normal faults (LANFs) slip seismogenically. In comparison to more steeply dipping (45-60?) normal faults, LANFs have the potential to produce stronger shaking because of their increased possible rupture area in the seismogenic crust. While LANFs have been documented globally, examples of seismogenically
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Earthquake Hazards, Geologic Hazards Science Center

Digital datasets documenting subsurface data locations, topographic metrics, fault scarp mapping, and revised fault network for Crowley's Ridge, New Madrid Seismic Zone

This release provides the data and interpretations supporting evidence of late Quaternary faulting along Crowleys Ridge in the New Madrid seismic zone. The release includes location information for seismic reflection and airborne electromagnetic (AEM) data over Crowleys Ridge, a table of topographic metrics derived from analysis of the 10m National Elevation Dataset (NED) digital elevation model (
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Earthquake Hazards, Geologic Hazards Science Center

An updated stress map of the continental U.S. reveals heterogeneous intraplate stress

Earthquake focal mechanisms and stress inversion results for the conterminous United States.
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Natural Hazards, Earthquake Hazards, Geologic Hazards Science Center

Digital Surface Models for the northern 16 km of the 1983 Borah Peak earthquake rupture, northern Lost River fault zone (Idaho, USA)

We present high-resolution (10-cm pixel) digital surface models (DSMs) generated for the northern 16 km of the surface rupture associated with the 1983 Mw 6.9 Borah Peak earthquake. These DSMs were generated using Agisoft Photoscan (and Metashape) image-based modeling software and low-altitude aerial photographs acquired from unmanned aircraft systems and a tethered balloon. DSM files consist of G
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Natural Hazards, Earthquake Hazards, Geologic Hazards Science Center

Data Set S1 for "Coseismic Sackungen in the New Madrid Seismic Zone, USA"

The New Madrid Seismic Zone presents significant seismic hazard to the central and eastern United States. We mapped newly-identified coseismic ridge-spreading features, or sackungen, in the bluffs east of the Mississippi River in western Tennessee. We use this mapping dataset in an accompanying manuscript to show that sackungen form during earthquakes on the Reelfoot fault and may fail in preferre
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Earthquake Hazards, Geologic Hazards Science Center
Filter Total Items: 52

Climatic influence on the expression of strike-slip faulting

Earthquakes on strike-slip faults are preserved in the geomorphic record by offset landforms that span a range of displacements, from small offsets created in the most recent earthquake (MRE) to large offsets that record cumulative slip from multiple prior events. An exponential decay in the number of large cumulative offsets has been observed on many faults, and a leading hypothesis is that clima
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Natural Hazards, Earthquake Hazards, Geologic Hazards Science Center

Seismic sources in the aleutian cradle of tsunamis

No abstract available.
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Natural Hazards, Earthquake Hazards, Alaska Science Center, Geologic Hazards Science Center

Simplifying complex fault data for systems-level analysis: Earthquake geology inputs for U.S. NSHM 2023

As part of the U.S. National Seismic Hazard Model (NSHM) update planned for 2023, two databases were prepared to more completely represent Quaternary-active faulting across the western United States: the NSHM23 fault sections database (FSD) and earthquake geology database (EQGeoDB). In prior iterations of NSHM, fault sections were included only if a field-measurement-derived slip rate was estimate
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Natural Hazards, Earthquake Hazards, Earthquake Science Center, Geologic Hazards Science Center

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)?

We excavated trenches at two paleoseismic sites bounding a trans-basin bedrock ridge (the Willow Creek Hills) along the northern Lost River fault zone to explore the uniqueness of the 1983 Mw 6.9 Borah Peak earthquake compared to its prehistoric predecessors. At the Sheep Creek site on the southernmost Warm Springs section, two earthquakes occurred at 9.8−14.0 ka (95% confidence) and 6.5−7.1 ka; e
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Natural Hazards, Geologic Hazards Science Center

Changing impacts of Alaska-Aleutian subduction zone tsunamis in California under future sea-level rise

The amplification of coastal hazards such as distant-source tsunamis under future relative sea-level rise (RSLR) is poorly constrained. In southern California, the Alaska-Aleutian subduction zone has been identified as an earthquake source region of particular concern for a worst-case scenario distant-source tsunami. Here, we explore how RSLR over the next century will influence future maximum nea
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Alaska Science Center

STEPS: Slip time earthquake path simulations applied to the San Andreas and Toe Jam Hill Faults to redefine geologic slip rate uncertainty

Geologic slip rates are a time-averaged measurement of fault displacement calculated over hundreds to million-year time scales and are a primary input for probabilistic seismic hazard analyses, which forecast expected ground shaking in future earthquakes. Despite their utility for seismic hazard calculations, longer-term geologic slip rates represent a time-averaged measure of the tempo of strain
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Natural Hazards, Earthquake Hazards, Earthquake Science Center, Geologic Hazards Science Center

Geophysical constraints on the crustal architecture of the transtensional Warm Springs Valley fault zone, northern Walker Lane, western Nevada, USA

The Walker Lane is a zone of distributed transtension where normal faults are overprinted by strike-slip motion. We use two newly-acquired high-resolution seismic reflection profiles and a reprocessed Consortium for Continental Reflection Profiling (COCORP) deep crustal reflection profile to assess the subsurface geometry of the Holocene-active, transtensional Warm Springs Valley fault zone (WSVFZ
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Natural Hazards, Geologic Hazards Science Center

Quaternary reelfoot fault deformation in the Obion River Valley, Tennessee, USA

Blind reverse faults are challenging to detect, and earthquake records can be elusive because deep fault slip does not break the surface along readily recognized scarps. The blind Reelfoot fault in the New Madrid seismic zone in the central United States has been the subject of extensive prior investigation; however, the extent of slip at the southern portion of the fault remains unconstrained. In
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Natural Hazards, Geologic Hazards Science Center

Quick and dirty (and accurate) 3-D paleoseismic trench models using coded scale bars

Structure‐from‐motion (SfM) modeling has dramatically increased the speed of generating geometrically accurate orthophoto mosaics of paleoseismic trenches, but some aspects of this technique remain time and labor intensive. Model accuracy relies on control points to establish scale, reduce distortion, and orient 3D models. Traditional SfM methods use total station or Global Navigation Satellite Sy
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Natural Hazards, Geologic Hazards Science Center

Holocene paleoseismology of the Steamboat Mountain Site: Evidence for full‐Llngth rupture of the Teton Fault, Wyoming

The 72‐km‐long Teton fault in northwestern Wyoming is an ideal candidate for reconstructing the lateral extent of surface‐rupturing earthquakes and testing models of normal‐fault segmentation. To explore the history of earthquakes on the northern Teton fault, we hand‐excavated two trenches at the Steamboat Mountain site, where the east‐dipping Teton fault has vertically displaced west‐sloping allu
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Natural Hazards, Geologic Hazards Science Center, Geosciences and Environmental Change Science Center

Seismic reflection imaging of the low-angle Panamint normal fault system, eastern California

Shallowly dipping (
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Natural Hazards, Earthquake Hazards, Geologic Hazards Science Center

Evidence for late Quaternary deformation along Crowley's Ridge, New Madrid seismic zone

The New Madrid seismic zone has been the source of multiple major (M ~7.0–7.5) earthquakes in the past 2 ka, yet the surface expression of recent deformation remains ambiguous. Crowleys Ridge, a linear ridge trending north‐south for 300+ km through the Mississippi Embayment, has been interpreted as either a fault‐bounded uplift or a nontectonic erosional remnant. New and previously published seism
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Natural Hazards, Geologic Hazards Science Center

STEPS: Slip Time Earthquake Path Simulations applied to the San Andreas and Toe Jam Hill faults to redefine geologic slip rate uncertainty (Matlab code)

Geologic slip rates are a time-averaged measurement of fault displacement calculated over 100s- to 1,000,000-year time scales and are a primary input for probabilistic seismic hazard analyses (PSHA), which forecast expected ground shaking in future earthquakes. Despite their utility for seismic hazard calculations, longer-term geologic slip rates represent a time-averaged measure of the tempo of s
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Natural Hazards, Earthquake Hazards, Geologic Hazards Science Center
Image: Geologic Studies on Sitkinak Island, Alaska
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Image: Geologic Studies on Sitkinak Island, Alaska
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Image: Geologic Studies on Sitkinak Island, Alaska
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Image: Geologic Studies on Sitkinak Island, Alaska
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Image: Geologic Studies on Sitkinak Island, Alaska
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Image: Geologic Studies on Sitkinak Island, Alaska
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Science and Products