As an earthquake geologist, I use numerical modeling, field observations, and quantitative analysis of remotely sensed data to investigate earthquake history of active faults and how earthquake history is recorded in a landscape. This work informs seismic hazard models and future risk.
I co-led the USGS-Hazards Unlearning Racism in Geoscience (URGE) pod and am invovled with ongoing JEDI/DEIA efforts at the GHSC and USGS. Please email me to chat more about unlearning racism in geoscience, the URGE program, and ongoing efforts.
Professional Experience
Research Geologist, USGS, 2020-Present
Geologist, USGS, 2014-2016
Physical Science Technician, Denali National Park, 2010, 2011, 2013
Education and Certifications
PhD, University of Colorado Boulder, 2016-2020
MS, University of Colorado Boulder, 2011-2013
BA, Vassar College, 2006-2010
Science and Products
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.
Filter Total Items: 13
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
The influence of frost weathering on the debris flow sediment supply in an alpine basin
Rocky, alpine mountains are prone to mass wasting from debris flows. The Chalk Cliffs
study area (central Colorado, USA) produces debris flows annually. These debris flows
are triggered when overland flow driven by intense summer convective storms mobilizes
large volumes of sediment within the channel network. Understanding the debris flow
hazard in this, and similar alpine settings, requires
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
Holocene rupture history of the central Teton fault at Leigh Lake; Grand Teton National Park, Wyoming
Prominent scarps on Pinedale glacial surfaces along the eastern base of the Teton Range confirm latest Pleistocene to Holocene surface‐faulting earthquakes on the Teton fault, but the timing of these events is only broadly constrained by a single previous paleoseismic study. We excavated two trenches at the Leigh Lake site near the center of the Teton fault to address open questions about earthqua
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
Paleoseismic results from the Alpine site, Wasatch fault zone: Timing and displacement data for six holocene earthquakes at the Salt Lake City–Provo segment boundary
To improve the characterization of Holocene earthquakes on the Wasatch fault zone (WFZ), we conducted light detection and ranging (lidar)‐based neotectonic mapping and excavated a paleoseismic trench across an 8‐m‐high fault scarp near Alpine, Utah, located ∼6.2–0.4 ka∼6.2–0.4 ka. Interseismic recurrence ranges from 0.2 to 1.8 ky (mean 1.2 ky). We estimate 6.5±0.7 m6.5±0.7 m of cumulative vert
Combining conflicting Bayesian models to develop paleoseismic records—An example from the Wasatch Fault Zone, Utah
Bayesian statistical analyses of paleoseismic data result in the probabilistic determination of earthquake times using geochronological data evaluated in the context of a stratigraphic model. However, a fundamental problem in paleoseismology is how to use the Bayesian approach to model sparse and/or conflicting geochronological datasets, such as those derived from sites exhibiting episodic sedimen
P- and S-wave velocity models incorporating the Cascadia subduction zone for 3D earthquake ground motion simulations, Version 1.6—Update for Open-File Report 2007–1348
In support of earthquake hazard studies and ground motion simulations in the Pacific Northwest, three-dimensional P- and S-wave velocity (VP and VS, respectively) models incorporating the Cascadia subduction zone were previously developed for the region encompassed from about 40.2°N. to 50°N. latitude, and from about 122°W. to 129°W. longitude. This report describes updates to the Cascadia velocit
Recurrent Holocene movement on the Susitna Glacier Thrust Fault: The structure that initiated the Mw 7.9 Denali Fault earthquake, central Alaska
We conducted a trench investigation and analyzed pre‐ and postearthquake topography to determine the timing and size of prehistoric surface ruptures on the Susitna Glacier fault (SGF), the thrust fault that initiated the 2002 Mw 7.9 Denali fault earthquake sequence in central Alaska. In two of our three hand‐excavated trenches, we found clear evidence for a single pre‐2002 earthquake (penultimate
Holocene earthquakes of magnitude 7 during westward escape of the Olympic Mountains, Washington
The Lake Creek–Boundary Creek fault, previously mapped in Miocene bedrock as an oblique thrust on the north flank of the Olympic Mountains, poses a significant earthquake hazard. Mapping using 2015 light detection and ranging (lidar) confirms 2004 lidar mapping of postglacial (≥14 km along a splay fault, the Sadie Creek fault, west of Lake Crescent. Scarp morphology suggests repeated earthquake r
On- and off-fault deformation associated with the September 2013 Mw7.7 Balochistan earthquake: Implications for geologic slip rate measurements
The 24 September 2013 Mw7.7 Balochistan, Pakistan earthquake ruptured a ~ 200 km-long stretch of the Hoshab fault in southern Pakistan and produced the second-largest lateral surface displacement observed for a continental strike-slip earthquake. We remotely measured surface deformation associated with this event using high-resolution (0.5 m) pre- and post-event satellite optical imagery. We docum
High‐resolution trench photomosaics from image‐based modeling: Workflow and error analysis
Photomosaics are commonly used to construct maps of paleoseismic trench exposures, but the conventional process of manually using image‐editing software is time consuming and produces undesirable artifacts and distortions. Herein, we document and evaluate the application of image‐based modeling (IBM) for creating photomosaics and 3D models of paleoseismic trench exposures, illustrated with a case‐
Pre-USGS Publications
Reitman, N.G. and P. Molnar (2021) Strain and velocity across the Great Basin derived from 15-ka fault slip rates: Implications for continuous deformation and seismic hazards in the Walker Lane, California-Nevada, USA. Tectonics. doi: 10.1029/2020TC006389
Reitman, N.G. and P. Molnar (2020) Input parameters, output data, and script to calculate strain and velocity from fault source parameters. [Data set]. Zenodo. https://doi.org/10.5281/zenodo.3895334
Reitman, N.G., K.J. Mueller, G.E. Tucker, R.D. Gold, R.W. Briggs, and K.R. Barnhart. (2019) Numerical model code and input files to run landscape evolution models with strike-slip faulting and measure channel offsets. [Data set]. Zenodo. http://doi.org/10.5281/zenodo.3374026
Litchfield, N.J., K.J. Clark, U.A. Cochran, J. Mountjoy, C. Mueller, R. Morgenstern, K.R. Berryman, B.G. McFadgen, R. Steele, N.G. Reitman, J. Howarth, and P. Villamor. (2020) Unraveling complex coastal deformation mechanisms using marine terrace paleoseismology Puatai Beach and Pakarae River mouth, northern Hikurangi Margin, New Zealand. Bulletin of the Seismological Society of America. doi: 10.1785/0120190208
Reitman, N.G., Ge, S., and Mueller, K. (2014) Groundwater flow and its effect on salt dissolution in Gypsum Canyon watershed, Paradox Basin, southeast Utah, USA. Hydrogeology Journal, doi: 10.1007/s10040-014-1126-0.
Plotting multiple fault representations: Applications for National Seismic Hazard Model 2023 update (NSHM-faultmaps)
The National Seismic Hazard Model (NSHM) utilizes a fault sections database (FSD) throughout the model workflow. Working towards a 2023 NSHM release, the NSHM23 FSD encompasses a major update with the addition of new fault sections, as well as the revision of existing fault sections from prior FSD (2014). The additions and revisions were largely based on the U.S. Geological Survey's Quaternary Fau
Science and Products
- Science
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. - Publications
Filter Total Items: 13
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; eThe influence of frost weathering on the debris flow sediment supply in an alpine basin
Rocky, alpine mountains are prone to mass wasting from debris flows. The Chalk Cliffs study area (central Colorado, USA) produces debris flows annually. These debris flows are triggered when overland flow driven by intense summer convective storms mobilizes large volumes of sediment within the channel network. Understanding the debris flow hazard in this, and similar alpine settings, requiresOffset 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 simuHolocene rupture history of the central Teton fault at Leigh Lake; Grand Teton National Park, Wyoming
Prominent scarps on Pinedale glacial surfaces along the eastern base of the Teton Range confirm latest Pleistocene to Holocene surface‐faulting earthquakes on the Teton fault, but the timing of these events is only broadly constrained by a single previous paleoseismic study. We excavated two trenches at the Leigh Lake site near the center of the Teton fault to address open questions about earthquaVariable 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 explPaleoseismic results from the Alpine site, Wasatch fault zone: Timing and displacement data for six holocene earthquakes at the Salt Lake City–Provo segment boundary
To improve the characterization of Holocene earthquakes on the Wasatch fault zone (WFZ), we conducted light detection and ranging (lidar)‐based neotectonic mapping and excavated a paleoseismic trench across an 8‐m‐high fault scarp near Alpine, Utah, located ∼6.2–0.4 ka∼6.2–0.4 ka. Interseismic recurrence ranges from 0.2 to 1.8 ky (mean 1.2 ky). We estimate 6.5±0.7 m6.5±0.7 m of cumulative vertCombining conflicting Bayesian models to develop paleoseismic records—An example from the Wasatch Fault Zone, Utah
Bayesian statistical analyses of paleoseismic data result in the probabilistic determination of earthquake times using geochronological data evaluated in the context of a stratigraphic model. However, a fundamental problem in paleoseismology is how to use the Bayesian approach to model sparse and/or conflicting geochronological datasets, such as those derived from sites exhibiting episodic sedimenP- and S-wave velocity models incorporating the Cascadia subduction zone for 3D earthquake ground motion simulations, Version 1.6—Update for Open-File Report 2007–1348
In support of earthquake hazard studies and ground motion simulations in the Pacific Northwest, three-dimensional P- and S-wave velocity (VP and VS, respectively) models incorporating the Cascadia subduction zone were previously developed for the region encompassed from about 40.2°N. to 50°N. latitude, and from about 122°W. to 129°W. longitude. This report describes updates to the Cascadia velocitRecurrent Holocene movement on the Susitna Glacier Thrust Fault: The structure that initiated the Mw 7.9 Denali Fault earthquake, central Alaska
We conducted a trench investigation and analyzed pre‐ and postearthquake topography to determine the timing and size of prehistoric surface ruptures on the Susitna Glacier fault (SGF), the thrust fault that initiated the 2002 Mw 7.9 Denali fault earthquake sequence in central Alaska. In two of our three hand‐excavated trenches, we found clear evidence for a single pre‐2002 earthquake (penultimateHolocene earthquakes of magnitude 7 during westward escape of the Olympic Mountains, Washington
The Lake Creek–Boundary Creek fault, previously mapped in Miocene bedrock as an oblique thrust on the north flank of the Olympic Mountains, poses a significant earthquake hazard. Mapping using 2015 light detection and ranging (lidar) confirms 2004 lidar mapping of postglacial (≥14 km along a splay fault, the Sadie Creek fault, west of Lake Crescent. Scarp morphology suggests repeated earthquake rOn- and off-fault deformation associated with the September 2013 Mw7.7 Balochistan earthquake: Implications for geologic slip rate measurements
The 24 September 2013 Mw7.7 Balochistan, Pakistan earthquake ruptured a ~ 200 km-long stretch of the Hoshab fault in southern Pakistan and produced the second-largest lateral surface displacement observed for a continental strike-slip earthquake. We remotely measured surface deformation associated with this event using high-resolution (0.5 m) pre- and post-event satellite optical imagery. We documHigh‐resolution trench photomosaics from image‐based modeling: Workflow and error analysis
Photomosaics are commonly used to construct maps of paleoseismic trench exposures, but the conventional process of manually using image‐editing software is time consuming and produces undesirable artifacts and distortions. Herein, we document and evaluate the application of image‐based modeling (IBM) for creating photomosaics and 3D models of paleoseismic trench exposures, illustrated with a case‐Pre-USGS Publications
Reitman, N.G. and P. Molnar (2021) Strain and velocity across the Great Basin derived from 15-ka fault slip rates: Implications for continuous deformation and seismic hazards in the Walker Lane, California-Nevada, USA. Tectonics. doi: 10.1029/2020TC006389Reitman, N.G. and P. Molnar (2020) Input parameters, output data, and script to calculate strain and velocity from fault source parameters. [Data set]. Zenodo. https://doi.org/10.5281/zenodo.3895334Reitman, N.G., K.J. Mueller, G.E. Tucker, R.D. Gold, R.W. Briggs, and K.R. Barnhart. (2019) Numerical model code and input files to run landscape evolution models with strike-slip faulting and measure channel offsets. [Data set]. Zenodo. http://doi.org/10.5281/zenodo.3374026Litchfield, N.J., K.J. Clark, U.A. Cochran, J. Mountjoy, C. Mueller, R. Morgenstern, K.R. Berryman, B.G. McFadgen, R. Steele, N.G. Reitman, J. Howarth, and P. Villamor. (2020) Unraveling complex coastal deformation mechanisms using marine terrace paleoseismology Puatai Beach and Pakarae River mouth, northern Hikurangi Margin, New Zealand. Bulletin of the Seismological Society of America. doi: 10.1785/0120190208Reitman, N.G., Ge, S., and Mueller, K. (2014) Groundwater flow and its effect on salt dissolution in Gypsum Canyon watershed, Paradox Basin, southeast Utah, USA. Hydrogeology Journal, doi: 10.1007/s10040-014-1126-0. - Data
Plotting multiple fault representations: Applications for National Seismic Hazard Model 2023 update (NSHM-faultmaps)
The National Seismic Hazard Model (NSHM) utilizes a fault sections database (FSD) throughout the model workflow. Working towards a 2023 NSHM release, the NSHM23 FSD encompasses a major update with the addition of new fault sections, as well as the revision of existing fault sections from prior FSD (2014). The additions and revisions were largely based on the U.S. Geological Survey's Quaternary Fau