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Andrew Graber, Ph.D.

Andrew Graber is a Research Geologist in the Landslide Hazards Program.

Andrew uses field, modeling, and remote sensing tools to study landslide hazards at a variety of spatial scales. His current projects focus on the changes in debris flow hazards following wildfire in response to recovery of vegetation and soil in burned areas.

Professional Experience

  • 2025 - Present: Research Geologist, USGS Geologic Hazards Science Center, Golden, CO

  • 2022-2025: Research Geologist (Mendenhall), USGS Geologic Hazards Science Center, Golden, CO

Education and Certifications

  • 2017-2022 Colorado School of Mines, Ph.D. Geological Engineering

  • 2012-2016 Wheaton College, B.S. Geology

Science and Products

a hillslope in a burned forest partially covered with new vegetation

Postfire Recovery

“How long, after wildfire do I need to be concerned about debris flows in my area?” The USGS conducts research to evaluate the recovery of burned areas using field monitoring stations, satellite-based data, and numerical models. This work facilitates the development of USGS hazard assessment products that are geared to answer this question.
By
Landslide Hazards Program
Postfire Recovery

Postfire Recovery

“How long, after wildfire do I need to be concerned about debris flows in my area?” The USGS conducts research to evaluate the recovery of burned areas using field monitoring stations, satellite-based data, and numerical models. This work facilitates the development of USGS hazard assessment products that are geared to answer this question.
Learn More

Post-Wildfire Debris-Flow Runout Hazard Assessment (PWFDF-R) Collection (updated 20260423) Post-Wildfire Debris-Flow Runout Hazard Assessment (PWFDF-R) Collection (updated 20260423)

Wildfire can substantially alter the hydrologic response of watersheds to rainfall, and debris-flow activity is among the most destructive consequences of these events. To assist federal, state, and local agencies in planning for postfire hazards, the U.S. Geological Survey conducts debris-flow hazard runout assessments. This collection contains the results of those assessments conducted...
By
Geologic Hazards Science Center

Precipitation Intensity Estimates for a One-Year Recurrence Interval for the Continental United States Precipitation Intensity Estimates for a One-Year Recurrence Interval for the Continental United States

This dataset provides precipitation intensity estimates for a one-year recurrence interval for the Continental United States as cloud-optimized GeoTIFFs (COGs). The release includes COGs for 15-minute, 30-minute, and 60-minute rainfall durations, and the precipitation intensities for these durations are referred to as I15, I30, and I60, respectively. Each raster reports precipitation...
By
Geologic Hazards Science Center

Landslide, soil, and vegetation measurements following an atmospheric river storm on January 9, 2023, in the Santa Ynez Mountains, California, USA Landslide, soil, and vegetation measurements following an atmospheric river storm on January 9, 2023, in the Santa Ynez Mountains, California, USA

An atmospheric river storm on January 9, 2023, produced widespread landsliding in the Santa Ynez Mountains in Santa Barbara County and Ventura County, California (USA). Landslides occurred in the footprint of the 2008 Tea Fire, 2009 Jesusita Fire, 2017 Thomas Fire, and 2019 Cave Fire, as well as in areas that had not burned in more than 15 years. Most of these landslides were shallow...
By
Landslide Hazards Program, Geologic Hazards Science Center

Post-Wildfire Debris-Flow Hazard Assessment (PWFDF) Collection Post-Wildfire Debris-Flow Hazard Assessment (PWFDF) Collection

Wildfire can substantially alter the hydrologic response of watersheds to rainfall, and debris-flow activity is among the most destructive consequences of these events. To assist federal, state, and local agencies in planning for postfire hazards, the U.S. Geological Survey conducts debris-flow hazard assessments for recent wildfires. This collection contains the results of those...
By
Landslide Hazards Program, Geologic Hazards Science Center

Compilation of runoff-generated debris-flow inventories for 18 fires across Arizona, California, Colorado, New Mexico, Utah, and Washington, USA Compilation of runoff-generated debris-flow inventories for 18 fires across Arizona, California, Colorado, New Mexico, Utah, and Washington, USA

Description This data release is an inventory of runoff-generated postfire debris flows compiled from 18 burn areas across six western U.S. states. Debris-flow data from the following fires are included: Arizona: 2019 Museum, 2021 Flag, and 2022 Pipeline Fires California: 2014 Silverado, 2015 Valley, 2019 Briceburg, 2020 Dolan, 2020 El Dorado, 2020 Lake, and 2021 Dixie Fires Colorado...
By
Landslide Hazards Program, Geologic Hazards Science Center, Supplemental Appropriations for Disaster Recovery Activities

Compilation of runoff-generated debris-flow inventories for 17 fires across Arizona, California, Colorado, New Mexico, and Washington, USA Compilation of runoff-generated debris-flow inventories for 17 fires across Arizona, California, Colorado, New Mexico, and Washington, USA

Summary This data release is an inventory of runoff-generated postfire debris flows compiled from 17 burn areas across five western U.S. states. Debris-flow data from the following fires are included: Arizona: 2017 Pinal and 2019 Woodbury Fires California: 2020 Apple, 2020 Bond, 2015 Butte, 2020 El Dorado, 2014 El Portal, 2018 Ferguson, 2016 Fish (San Gabriel Complex), 2011 Motor, and...
By
Landslide Hazards Program, Geologic Hazards Science Center, Supplemental Appropriations for Disaster Recovery Activities

Field-verified inventory of postfire debris flows for the 2021 Dixie Fire following a 23-25 October 2021 atmospheric river storm and 12 June 2022 thunderstorm Field-verified inventory of postfire debris flows for the 2021 Dixie Fire following a 23-25 October 2021 atmospheric river storm and 12 June 2022 thunderstorm

Summary This data release is a field-verified inventory of postfire debris flows for the 2021 Dixie Fire following a 23-25 October 2021 atmospheric river storm and 12 June 2022 thunderstorm. The “README.txt” file describes the fields for the “Inventory.csv” file. The “Chambers” and “Chips” rain gage data referenced in the inventory are included as: “Chambers-Oct2021-Storm.csv”, “Chambers...
By
Geologic Hazards Science Center, Supplemental Appropriations for Disaster Recovery Activities

Characterizing changes in postfire debris-flow hazard as burned areas recover Characterizing changes in postfire debris-flow hazard as burned areas recover

Emergency assessments of postfire debris-flow hazards that are performed by the U.S. Geological Survey (USGS) provide estimates of debris-flow likelihood and rainfall triggering conditions that are used for evaluating and managing runoff-generated debris-flow hazards in recently burned areas throughout the western United States. Although the immediate postfire period, within roughly one...
Authors
Andrew Paul Graber, Matthew A. Thomas, Jason W. Kean, Jonathan Michael King, Jaime Kostelnik
By
Geologic Hazards Science Center

Landsliding follows signatures of wildfire history and vegetative regrowth in a steep coastal shrubland Landsliding follows signatures of wildfire history and vegetative regrowth in a steep coastal shrubland

Five years after the deadly and destructive 9 January 2018 Montecito debris flows (Santa Barbara County, California, USA), an atmospheric river storm on 9 January 2023 triggered widespread landsliding that affected many of the same drainages in the Santa Ynez Mountains. Using high-resolution aerial imagery, we identified >10,000 landslides over an ∼160 km2 area. Most of the landslides...
Authors
Matthew A. Thomas, Donald N. Lindsay, Jason W. Kean, Andrew Paul Graber, Rebecca K. Rossi, Jaime Kostelnik, Francis K. Rengers, Jonathan Y. Schwartz, Brian J. Swanson, Nina S. Oakley, Paul W. Richardson, Alexander E. Morelan, Andrew C. Ritchie, Jonathan A. Warrick, Lindsey L. Rotche, Brian D. Penserini, Stephen L. Slaughter
By
Landslide Hazards Program, Geologic Hazards Science Center

How long do runoff-generated debris-flow hazards persist after wildfire? How long do runoff-generated debris-flow hazards persist after wildfire?

Runoff-generated debris flows are a potentially destructive and deadly response to wildfire until sufficient vegetation and soil-hydraulic recovery have reduced susceptibility to the hazard. Elevated debris-flow susceptibility may persist for several years, but the controls on the timespan of the susceptible period are poorly understood. To evaluate the connection between vegetation...
Authors
Andrew Paul Graber, Matthew A. Thomas, Jason W. Kean
By
Natural Hazards Mission Area, Landslide Hazards Program, Geologic Hazards Science Center, Supplemental Appropriations for Disaster Recovery Activities

The rainfall intensity-duration control of debris flows after wildfire The rainfall intensity-duration control of debris flows after wildfire

Increased wildfire activity in the western United States has exposed regional gaps in our understanding of postfire debris-flow generation. To address this problem, we characterized flows in an unstudied area to test the rainfall intensity-duration control of the hazard. Our rainfall measurements and field observations from the northern Sierra Nevada (California, USA) show that debris...
Authors
Matthew A. Thomas, Donald N. Lindsay, David B. Cavagnaro, Jason W. Kean, Scott W. McCoy, Andrew Paul Graber
By
Natural Hazards Mission Area, Landslide Hazards Program, Geologic Hazards Science Center, Supplemental Appropriations for Disaster Recovery Activities

Non-USGS Publications**

Graber, A., Santi, P. (2023) UAV-photogrammetry rockfall monitoring of natural slopes in Glenwood Canyon, CO, USA: background activity and post-wildfire impacts. Landslides 20, 229–248. https://doi.org/10.1007/s10346-022-01974-9
Graber, A., & Santi, P. (2022). Power law models for rockfall frequency-magnitude distributions: review and identification of factors that influence the scaling exponent. Geomorphology, 418, 108463. https://doi.org/10.1016/J.GEOMORPH.2022.108463
Graber, A., & Santi, P. (2022). Inferring rockfall frequency-magnitude relationships and talus accumulation times from lichenometric study of talus deposits, Glenwood Canyon, CO, USA. Geomorphology, 408, 108253. https://doi.org/10.1016/J.GEOMORPH.2022.108253
Graber, A., Santi, P. & Meza Arestegui, P. (2021) Constraining the critical groundwater conditions for initiation of large, irrigation-induced landslides, Siguas River Valley, Peru. Landslides 18, 3753–3767. https://doi.org/10.1007/s10346-021-01767-6

**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.

distant hillslopes covered in burnt trees distant hillslopes covered in burnt trees
Updating methods for postfire debris-flow hazard assessment
distant hillslopes covered in burnt trees

Updating methods for postfire debris-flow hazard assessment

Updating methods for postfire debris-flow hazard assessment

For more than a decade, the U.S.

By
Landslide Hazards Program, Geologic Hazards Science Center
distant hillslopes covered in burnt trees

Updating methods for postfire debris-flow hazard assessment

Updating methods for postfire debris-flow hazard assessment

For more than a decade, the U.S.

By
Landslide Hazards Program, Geologic Hazards Science Center

Science and Products

a hillslope in a burned forest partially covered with new vegetation

Postfire Recovery

“How long, after wildfire do I need to be concerned about debris flows in my area?” The USGS conducts research to evaluate the recovery of burned areas using field monitoring stations, satellite-based data, and numerical models. This work facilitates the development of USGS hazard assessment products that are geared to answer this question.
By
Landslide Hazards Program
Postfire Recovery

Postfire Recovery

“How long, after wildfire do I need to be concerned about debris flows in my area?” The USGS conducts research to evaluate the recovery of burned areas using field monitoring stations, satellite-based data, and numerical models. This work facilitates the development of USGS hazard assessment products that are geared to answer this question.
Learn More

Post-Wildfire Debris-Flow Runout Hazard Assessment (PWFDF-R) Collection (updated 20260423) Post-Wildfire Debris-Flow Runout Hazard Assessment (PWFDF-R) Collection (updated 20260423)

Wildfire can substantially alter the hydrologic response of watersheds to rainfall, and debris-flow activity is among the most destructive consequences of these events. To assist federal, state, and local agencies in planning for postfire hazards, the U.S. Geological Survey conducts debris-flow hazard runout assessments. This collection contains the results of those assessments conducted...
By
Geologic Hazards Science Center

Precipitation Intensity Estimates for a One-Year Recurrence Interval for the Continental United States Precipitation Intensity Estimates for a One-Year Recurrence Interval for the Continental United States

This dataset provides precipitation intensity estimates for a one-year recurrence interval for the Continental United States as cloud-optimized GeoTIFFs (COGs). The release includes COGs for 15-minute, 30-minute, and 60-minute rainfall durations, and the precipitation intensities for these durations are referred to as I15, I30, and I60, respectively. Each raster reports precipitation...
By
Geologic Hazards Science Center

Landslide, soil, and vegetation measurements following an atmospheric river storm on January 9, 2023, in the Santa Ynez Mountains, California, USA Landslide, soil, and vegetation measurements following an atmospheric river storm on January 9, 2023, in the Santa Ynez Mountains, California, USA

An atmospheric river storm on January 9, 2023, produced widespread landsliding in the Santa Ynez Mountains in Santa Barbara County and Ventura County, California (USA). Landslides occurred in the footprint of the 2008 Tea Fire, 2009 Jesusita Fire, 2017 Thomas Fire, and 2019 Cave Fire, as well as in areas that had not burned in more than 15 years. Most of these landslides were shallow...
By
Landslide Hazards Program, Geologic Hazards Science Center

Post-Wildfire Debris-Flow Hazard Assessment (PWFDF) Collection Post-Wildfire Debris-Flow Hazard Assessment (PWFDF) Collection

Wildfire can substantially alter the hydrologic response of watersheds to rainfall, and debris-flow activity is among the most destructive consequences of these events. To assist federal, state, and local agencies in planning for postfire hazards, the U.S. Geological Survey conducts debris-flow hazard assessments for recent wildfires. This collection contains the results of those...
By
Landslide Hazards Program, Geologic Hazards Science Center

Compilation of runoff-generated debris-flow inventories for 18 fires across Arizona, California, Colorado, New Mexico, Utah, and Washington, USA Compilation of runoff-generated debris-flow inventories for 18 fires across Arizona, California, Colorado, New Mexico, Utah, and Washington, USA

Description This data release is an inventory of runoff-generated postfire debris flows compiled from 18 burn areas across six western U.S. states. Debris-flow data from the following fires are included: Arizona: 2019 Museum, 2021 Flag, and 2022 Pipeline Fires California: 2014 Silverado, 2015 Valley, 2019 Briceburg, 2020 Dolan, 2020 El Dorado, 2020 Lake, and 2021 Dixie Fires Colorado...
By
Landslide Hazards Program, Geologic Hazards Science Center, Supplemental Appropriations for Disaster Recovery Activities

Compilation of runoff-generated debris-flow inventories for 17 fires across Arizona, California, Colorado, New Mexico, and Washington, USA Compilation of runoff-generated debris-flow inventories for 17 fires across Arizona, California, Colorado, New Mexico, and Washington, USA

Summary This data release is an inventory of runoff-generated postfire debris flows compiled from 17 burn areas across five western U.S. states. Debris-flow data from the following fires are included: Arizona: 2017 Pinal and 2019 Woodbury Fires California: 2020 Apple, 2020 Bond, 2015 Butte, 2020 El Dorado, 2014 El Portal, 2018 Ferguson, 2016 Fish (San Gabriel Complex), 2011 Motor, and...
By
Landslide Hazards Program, Geologic Hazards Science Center, Supplemental Appropriations for Disaster Recovery Activities

Field-verified inventory of postfire debris flows for the 2021 Dixie Fire following a 23-25 October 2021 atmospheric river storm and 12 June 2022 thunderstorm Field-verified inventory of postfire debris flows for the 2021 Dixie Fire following a 23-25 October 2021 atmospheric river storm and 12 June 2022 thunderstorm

Summary This data release is a field-verified inventory of postfire debris flows for the 2021 Dixie Fire following a 23-25 October 2021 atmospheric river storm and 12 June 2022 thunderstorm. The “README.txt” file describes the fields for the “Inventory.csv” file. The “Chambers” and “Chips” rain gage data referenced in the inventory are included as: “Chambers-Oct2021-Storm.csv”, “Chambers...
By
Geologic Hazards Science Center, Supplemental Appropriations for Disaster Recovery Activities

Characterizing changes in postfire debris-flow hazard as burned areas recover Characterizing changes in postfire debris-flow hazard as burned areas recover

Emergency assessments of postfire debris-flow hazards that are performed by the U.S. Geological Survey (USGS) provide estimates of debris-flow likelihood and rainfall triggering conditions that are used for evaluating and managing runoff-generated debris-flow hazards in recently burned areas throughout the western United States. Although the immediate postfire period, within roughly one...
Authors
Andrew Paul Graber, Matthew A. Thomas, Jason W. Kean, Jonathan Michael King, Jaime Kostelnik
By
Geologic Hazards Science Center

Landsliding follows signatures of wildfire history and vegetative regrowth in a steep coastal shrubland Landsliding follows signatures of wildfire history and vegetative regrowth in a steep coastal shrubland

Five years after the deadly and destructive 9 January 2018 Montecito debris flows (Santa Barbara County, California, USA), an atmospheric river storm on 9 January 2023 triggered widespread landsliding that affected many of the same drainages in the Santa Ynez Mountains. Using high-resolution aerial imagery, we identified >10,000 landslides over an ∼160 km2 area. Most of the landslides...
Authors
Matthew A. Thomas, Donald N. Lindsay, Jason W. Kean, Andrew Paul Graber, Rebecca K. Rossi, Jaime Kostelnik, Francis K. Rengers, Jonathan Y. Schwartz, Brian J. Swanson, Nina S. Oakley, Paul W. Richardson, Alexander E. Morelan, Andrew C. Ritchie, Jonathan A. Warrick, Lindsey L. Rotche, Brian D. Penserini, Stephen L. Slaughter
By
Landslide Hazards Program, Geologic Hazards Science Center

How long do runoff-generated debris-flow hazards persist after wildfire? How long do runoff-generated debris-flow hazards persist after wildfire?

Runoff-generated debris flows are a potentially destructive and deadly response to wildfire until sufficient vegetation and soil-hydraulic recovery have reduced susceptibility to the hazard. Elevated debris-flow susceptibility may persist for several years, but the controls on the timespan of the susceptible period are poorly understood. To evaluate the connection between vegetation...
Authors
Andrew Paul Graber, Matthew A. Thomas, Jason W. Kean
By
Natural Hazards Mission Area, Landslide Hazards Program, Geologic Hazards Science Center, Supplemental Appropriations for Disaster Recovery Activities

The rainfall intensity-duration control of debris flows after wildfire The rainfall intensity-duration control of debris flows after wildfire

Increased wildfire activity in the western United States has exposed regional gaps in our understanding of postfire debris-flow generation. To address this problem, we characterized flows in an unstudied area to test the rainfall intensity-duration control of the hazard. Our rainfall measurements and field observations from the northern Sierra Nevada (California, USA) show that debris...
Authors
Matthew A. Thomas, Donald N. Lindsay, David B. Cavagnaro, Jason W. Kean, Scott W. McCoy, Andrew Paul Graber
By
Natural Hazards Mission Area, Landslide Hazards Program, Geologic Hazards Science Center, Supplemental Appropriations for Disaster Recovery Activities

Non-USGS Publications**

Graber, A., Santi, P. (2023) UAV-photogrammetry rockfall monitoring of natural slopes in Glenwood Canyon, CO, USA: background activity and post-wildfire impacts. Landslides 20, 229–248. https://doi.org/10.1007/s10346-022-01974-9
Graber, A., & Santi, P. (2022). Power law models for rockfall frequency-magnitude distributions: review and identification of factors that influence the scaling exponent. Geomorphology, 418, 108463. https://doi.org/10.1016/J.GEOMORPH.2022.108463
Graber, A., & Santi, P. (2022). Inferring rockfall frequency-magnitude relationships and talus accumulation times from lichenometric study of talus deposits, Glenwood Canyon, CO, USA. Geomorphology, 408, 108253. https://doi.org/10.1016/J.GEOMORPH.2022.108253
Graber, A., Santi, P. & Meza Arestegui, P. (2021) Constraining the critical groundwater conditions for initiation of large, irrigation-induced landslides, Siguas River Valley, Peru. Landslides 18, 3753–3767. https://doi.org/10.1007/s10346-021-01767-6

**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.

distant hillslopes covered in burnt trees distant hillslopes covered in burnt trees
Updating methods for postfire debris-flow hazard assessment
distant hillslopes covered in burnt trees

Updating methods for postfire debris-flow hazard assessment

Updating methods for postfire debris-flow hazard assessment

For more than a decade, the U.S.

By
Landslide Hazards Program, Geologic Hazards Science Center
distant hillslopes covered in burnt trees

Updating methods for postfire debris-flow hazard assessment

Updating methods for postfire debris-flow hazard assessment

For more than a decade, the U.S.

By
Landslide Hazards Program, Geologic Hazards Science Center
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