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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, 2019New 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, 2019New 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, 2018The 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, 2018The 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.
Learn More
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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, 2015Paleoseismology 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, 2015Paleoseismology along the Wasatch Fault in Utah is helping to estimate the shaking risk to nearby towns.
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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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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

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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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

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

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

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: 46

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

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

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

Offset channels may not accurately record strike-slip fault displacement: Evidence from landscape evolution models

Slip distribution, slip rate, and slip per event for strike‐slip faults are commonly determined by correlating offset stream channels—under the assumption that they record seismic slip—but offset channels are formed by the interplay of tectonic and geomorphic processes. To constrain offset channel development under known tectonic and geomorphic conditions, we use numerical landscape evolution simu
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Natural Hazards, Geologic Hazards Science Center

Holocene earthquake history and slip rate of the southern Teton fault, Wyoming, USA

The 72-km-long Teton normal fault bounds the eastern base of the Teton Range in northwestern Wyoming, USA. Although geomorphic surfaces along the fault record latest Pleistocene to Holocene fault movement, the postglacial earthquake history of the fault has remained enigmatic. We excavated a paleoseismic trench at the Buffalo Bowl site along the southernmost part of the fault to determine its Holo
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Natural Hazards, Geologic Hazards Science Center

Relaxing segmentation on the Wasatch Fault Zone: Impact on seismic hazard

The multisegment Wasatch fault zone is a well-studied normal fault in the western United States that has paleoseismic evidence of recurrent Holocene surface-faulting earthquakes. Along the 270-km-long central part of the fault, four primary structural complexities provide possible along-strike limits to these ruptures and form the basis for models of fault segmentation. Here, we assess the impact
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Natural Hazards, Geologic Hazards Science Center

Variable normal-fault rupture behavior, northern Lost River fault zone, Idaho, USA

The 1983 Mw 6.9 Borah Peak earthquake generated ∼36 km of surface rupture along the Thousand Springs and Warm Springs sections of the Lost River fault zone (LRFZ, Idaho, USA). Although the rupture is a well-studied example of multisegment surface faulting, ambiguity remains regarding the degree to which a bedrock ridge and branch fault at the Willow Creek Hills influenced rupture progress. To expl
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Natural Hazards, Geologic Hazards Science Center

Surface rupture and distributed deformation revealed by optical satellite imagery: The intraplate 2016 Mw 6.0 Petermann Ranges earthquake, Australia

High-resolution optical satellite imagery is used to quantify vertical surface deformation associated with the intraplate 20 May 2016 Mw 6.0 Petermann Ranges earthquake, Northern Territory, Australia. The 21 ╓ 1 km long NW-trending rupture resulted from reverse motion on a northeast-dipping fault. Vertical surface offsets of up to 0.7 ╓ 0.1 m distributed across a 0.5-to-1 km wide deformation zone
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Natural Hazards, Geologic Hazards Science Center

Evidence for frequent, large tsunamis spanning locked and creeping parts of the Aleutian megathrust

At the eastern end of the 1957 Andreanof Islands magnitude-8.6 earthquake rupture, Driftwood Bay (Umnak Island) and Stardust Bay (Sedanka Island) lie along presently locked and creeping parts of the Aleutian megathrust, respectively, based on satellite geodesy onshore. Both bays, located 200-km apart, face the Aleutian trench and harbor coastal evidence for tsunami inundation in 1957. Here we desc
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Alaska Science Center, Pacific Coastal and Marine 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
By
Earthquake Hazards, Geologic Hazards Science Center

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