Rob Witter, Ph.D.
I conduct geological detective work that uncovers clues about the location, size, and frequency of ancient earthquakes and tsunamis. If we prepare for these hazards we can prevent future earthquakes and tsunamis from becoming future disasters.
I study prehistoric earthquakes along the Pacific-North American plate boundary. I apply aspects of geomorphology, paleoseismology, geodesy, and sea-level studies to decipher the geologic record of ancient earthquakes. Most of my work focuses on great subduction earthquakes capable of generating tsunamis. What I find out contributes to seismic and tsunami hazards assessments used to strengthen building codes and reduce tsunami risk.
Professional Experience
2011 – Present Research Geologist, U.S. Geological Survey, Alaska Science Center, Anchorage, AK
2006 – 2011 Regional Coastal Geologist, Oregon Department of Geology and Mineral Industries, Newport, OR
1999 – 2006 Senior Project Geologist, William Lettis & Associates, Inc., Walnut Creek, CA
Education and Certifications
Ph.D. 1999 University of Oregon, Eugene, OR Geoscience
B.A. 1991 Whitman College, Walla Walla, WA Biology
Science and Products
Filter Total Items: 19
Geophysical and core sample data collected in lakes and fjords of southcentral Alaska following the 2018 Anchorage earthquake (ver. 2.0, October 2023) Geophysical and core sample data collected in lakes and fjords of southcentral Alaska following the 2018 Anchorage earthquake (ver. 2.0, October 2023)
This dataset includes sub-bottom seismic and sediment core data collected during USGS field activities 2021-612-FA, 2020-625-FA, and 2020-615-FA. Sub-bottom data include Chirp seismic in SEG-Y format with associated navigation tracklines. Core data include photo and computed tomography (CT) scans, and various mineralogical, radiometric, and other sampling data. Users are advised to read...
Radiocarbon and Luminescence Data for Fairweather Fault Investigation, Glacier Bay National Park, Southeast Alaska Radiocarbon and Luminescence Data for Fairweather Fault Investigation, Glacier Bay National Park, Southeast Alaska
This dataset is comprised of two tables with age data along the Fairweather fault in Glacier Bay National Park. The tables are: (1) radiocarbon dates analyzed at the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS), and (2) infrared stimulated luminescence ages determined by the Utah State University (USU) Luminescence Laboratory.
Gridded Data from Multibeam Bathymetric Surveys of Eklutna, Kenai, and Skilak Lakes, Alaska Gridded Data from Multibeam Bathymetric Surveys of Eklutna, Kenai, and Skilak Lakes, Alaska
This dataset contains bathymetric depth values for three lakes in southcentral Alaska: Eklutna Lake near the city of Anchorage, Kenai Lake near the city of Cooper Landing, and Skilak Lake near the city of Soldotna. Values are in negative meters and measured relative to the North American Vertical Datum of 1988. The data release consists of a raster grids (Eklutna = 4 m; Kenai = 9 m...
Field reconnaissance of ground failure triggered by shaking during the 2018 M7.1 Anchorage, Alaska, earthquake Field reconnaissance of ground failure triggered by shaking during the 2018 M7.1 Anchorage, Alaska, earthquake
These data present geolocated photographs, GPS tracks, and field-mapped ground failures collected during the USGS reconnaissance of ground failures following the 2018 M7.1 Anchorage Earthquake.
Airborne Lidar-based Digital Elevation Models of Coastal Montague Island (Alaska) Acquired September 2018 Airborne Lidar-based Digital Elevation Models of Coastal Montague Island (Alaska) Acquired September 2018
This dataset provides a digital elevation model mosaic derived from airborne lidar data acquired in 2018 from September 2–3 over eight separate areas along Alaska's Montague Island coast, between Prince William Sound and the Gulf of Alaska.
Radiocarbon, Cesium-137, Grain Size, and X-ray Fluorescence Data for Tsunami Geology Investigation, Driftwood Bay, Umnak Island, Alaska (2018) Radiocarbon, Cesium-137, Grain Size, and X-ray Fluorescence Data for Tsunami Geology Investigation, Driftwood Bay, Umnak Island, Alaska (2018)
This dataset consists of nine tables that include radiocarbon dates, Cesium-137 activity, grain size measurements, and scanning X-ray fluorescence element intensity counts.
Filter Total Items: 26
No results found.
Filter Total Items: 57
Reproducibility and variability of earthquake subsidence estimates from saltmarshes of a Cascadia estuary Reproducibility and variability of earthquake subsidence estimates from saltmarshes of a Cascadia estuary
We examine fossil foraminiferal assemblages from 20 sediment cores to assess sudden relative sea-level (RSL) changes across three mud-over-peat contacts at three salt marshes in northern Humboldt Bay, California (~44.8°N, -124.2°W). We use a validated foraminiferal-based Bayesian transfer function to evaluate the variability of subsidence stratigraphy at a range of 30-6000 m across an...
Authors
Jason Scott Padgett, Simon E. Engelhart, Harvey M. Kelsey, Robert C. Witter, Niamh Cahill
Unravelling a 2300 year long sedimentary record of megathrust and intraslab earthquakes in proglacial Skilak Lake, south-central Alaska Unravelling a 2300 year long sedimentary record of megathrust and intraslab earthquakes in proglacial Skilak Lake, south-central Alaska
Seismic hazards in subduction settings typically arise from megathrust, intraslab and crustal earthquake sources. Despite the frequent occurrence of intraslab earthquakes in subduction zones and their potential threat to communities, their long-term recurrence behaviour is barely studied. Sedimentary sequences in lakes may register ground shaking from different seismic sources. This...
Authors
Nore Praet, Maarten Van Daele, Jasper Moernaut, Thomas Mestdagh, Thomas Vandorpe, Britta J.L. Jensen, Robert C. Witter, Peter J. Haeussler, Marc De Batist
Changing impacts of Alaska-Aleutian subduction zone tsunamis in California under future sea-level rise 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...
Authors
Tina Dura, Andra Garner, Robert Weiss, Robert E. Kopp, Simon E. Engelhart, Robert C. Witter, Richard W. Briggs, Charles Mueller, Alan Nelson, Benjamin P. Horton
Geomorphic expression and slip rate of the Fairweather fault, southeast Alaska, and evidence for predecessors of the 1958 rupture Geomorphic expression and slip rate of the Fairweather fault, southeast Alaska, and evidence for predecessors of the 1958 rupture
Active traces of the southern Fairweather fault were revealed by light detection and ranging (lidar) and show evidence for transpressional deformation between North America and the Yakutat block in southeast Alaska. We map the Holocene geomorphic expression of tectonic deformation along the southern 30 km of the Fairweather fault, which ruptured in the 1958 moment magnitude 7.8...
Authors
Robert C. Witter, Adrian Bender, Katherine M. Scharer, Christopher DuRoss, Peter J. Haeussler, Richard O. Lease
A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis
A new history of great earthquakes (and their tsunamis) for the central and southern Cascadia subduction zone shows more frequent (17 in the past 6700 yr) megathrust ruptures than previous coastal chronologies. The history is based on along-strike correlations of Bayesian age models derived from evaluation of 554 radiocarbon ages that date earthquake evidence at 14 coastal sites. We...
Authors
Alan Nelson, Christopher DuRoss, Robert C. Witter, Harvey M. Kelsey, Simon E. Engelhart, Shannon A. Mahan, Harrison J. Gray, Andrea D. Hawkes, Benjamin P. Horton, Jason S. Padgett
Extreme Quaternary plate boundary exhumation and strike slip localized along the southern Fairweather fault, Alaska, USA Extreme Quaternary plate boundary exhumation and strike slip localized along the southern Fairweather fault, Alaska, USA
The Fairweather fault (southeastern Alaska, USA) is Earth’s fastest-slipping intracontinental strike-slip fault, but its long-term role in localizing Yakutat–(Pacific–)North America plate motion is poorly constrained. This plate boundary fault transitions northward from pure strike slip to transpression where it comes onshore and undergoes a 6–8 km/m.y. exhumation rates that increases in...
Authors
Richard O. Lease, Peter J. Haeussler, Robert C. Witter, Daniel F. Stockli, Adrian Bender, Harvey Kelsey, Paul O’Sullivan
Non-USGS Publications**
Engelhart, S. E., Horton, B. P., Nelson, A. R., Hawkes, A. D., Witter, R. C., Wang, K., Wang P.-L., and Vane, C. H., 2013, Testing the use of microfossils to reconstruct great earthquakes at Cascadia, Geology, doi:10.1130/G34544.1.
Engelhart, S. E., B. P. Horton, C. H. Vane, A. R. Nelson, R. C. Witter, S. R. Brody, and A. D. Hawkes, 2013, Modern foraminifera, δ13C, and bulk geochemistry of central Oregon tidal marshes and their application in paleoseismology, Palaeogeography, Palaeoclimatology, Palaeoecology, doi:10.1016/j.palaeo.2013.02.032.
Kelson, K., R. C. Witter, A. Tassara, I. Ryder, C. Ledezma, G. Montalva, D. Frost, N. Sitar, R. Moss, and L. Johnson, 2012, Coseismic tectonic surface deformation during the 2012 Maule, Chile, Mw 8.8 earthquake, Earthquake Spectra, v. 28, n. S1, p. 39-54.
Pilarczyk, J. E., Horton, B. P., Witter, R. C., Vane, C. H., Chagué-Goff, C., Goff, J., 2012, Sedimentary and foraminiferal evidence of the 2011 Tohoku-oki tsunami on the Sendai coastal plain, Japan. Sedimentary Geology. doi:10.1016/j.sedgeo.2012.08.011.
Richmond, B., W. Szczucinski, C.Chague-Goff, K. Goto, D. Sugawara, R. Witter, D.R. Tappin, B. Jaffe, S. Fujino, Y. Nishimura, and J. Goff, 2012, Erosion, deposition and landscape change on the Sendai coastal plain, Japan, resulting from the March 11, 2011 Tohoku-oki tsunami, Sedimentary Geology, doi:10.1016/j.sedgeo.2012.08.005.
Witter, R.C., Y.J. Zhang, K. Wang, C. Goldfinger, and G.R. Priest, 2012, Coseismic slip on the southern Cascadia megathrust implied by tsunami deposits in an Oregon lake and earthquake-triggered marine turbidites, Journal of Geophysical Research, 117, B10303, doi:10.1029/2012JB009404.
Allan, J., P. Komar, P. Ruggiero, and R.C. Witter, 2012, The March 2011 Tohoku tsunami and its impacts along the U.S. West Coast, Journal of Coastal Research, Journal of Coastal Research, v. 28, n. 5, p. 1142-1153, doi:10.2112/jcoastres-d-11-00115.1.
Witter, R. C., B. Jaffe, Y. Zhang, and G. R. Priest, 2012, Reconstructing Hydrodynamic Flow Parameters of the 1700 Tsunami at Cannon Beach, Oregon, USA, Natural Hazards, doi:10.1007/s11069-011-9912-7.
Horton, B. P., Sawai, Y., Hawkes, A. D., and Witter, R. C., 2011, Sedimentology and paleontology of a tsunami deposit accompanying the great Chilean earthquake of February 2010: Marine Micropaleontology, v. 79, no. 3-4, p. 132–138, doi:10.1016/j.marmicro.2011.02.001
Zhang, Y. J., R. C. Witter, and G. R. Priest, 2011, Tsunami-tide interaction in 1964 Prince William Sound tsunami, Ocean Modelling, v. 40, p. 246–259, doi:10.1016/j.ocemod.2011.09.005
**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.
Science and Products
Filter Total Items: 19
Geophysical and core sample data collected in lakes and fjords of southcentral Alaska following the 2018 Anchorage earthquake (ver. 2.0, October 2023) Geophysical and core sample data collected in lakes and fjords of southcentral Alaska following the 2018 Anchorage earthquake (ver. 2.0, October 2023)
This dataset includes sub-bottom seismic and sediment core data collected during USGS field activities 2021-612-FA, 2020-625-FA, and 2020-615-FA. Sub-bottom data include Chirp seismic in SEG-Y format with associated navigation tracklines. Core data include photo and computed tomography (CT) scans, and various mineralogical, radiometric, and other sampling data. Users are advised to read...
Radiocarbon and Luminescence Data for Fairweather Fault Investigation, Glacier Bay National Park, Southeast Alaska Radiocarbon and Luminescence Data for Fairweather Fault Investigation, Glacier Bay National Park, Southeast Alaska
This dataset is comprised of two tables with age data along the Fairweather fault in Glacier Bay National Park. The tables are: (1) radiocarbon dates analyzed at the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS), and (2) infrared stimulated luminescence ages determined by the Utah State University (USU) Luminescence Laboratory.
Gridded Data from Multibeam Bathymetric Surveys of Eklutna, Kenai, and Skilak Lakes, Alaska Gridded Data from Multibeam Bathymetric Surveys of Eklutna, Kenai, and Skilak Lakes, Alaska
This dataset contains bathymetric depth values for three lakes in southcentral Alaska: Eklutna Lake near the city of Anchorage, Kenai Lake near the city of Cooper Landing, and Skilak Lake near the city of Soldotna. Values are in negative meters and measured relative to the North American Vertical Datum of 1988. The data release consists of a raster grids (Eklutna = 4 m; Kenai = 9 m...
Field reconnaissance of ground failure triggered by shaking during the 2018 M7.1 Anchorage, Alaska, earthquake Field reconnaissance of ground failure triggered by shaking during the 2018 M7.1 Anchorage, Alaska, earthquake
These data present geolocated photographs, GPS tracks, and field-mapped ground failures collected during the USGS reconnaissance of ground failures following the 2018 M7.1 Anchorage Earthquake.
Airborne Lidar-based Digital Elevation Models of Coastal Montague Island (Alaska) Acquired September 2018 Airborne Lidar-based Digital Elevation Models of Coastal Montague Island (Alaska) Acquired September 2018
This dataset provides a digital elevation model mosaic derived from airborne lidar data acquired in 2018 from September 2–3 over eight separate areas along Alaska's Montague Island coast, between Prince William Sound and the Gulf of Alaska.
Radiocarbon, Cesium-137, Grain Size, and X-ray Fluorescence Data for Tsunami Geology Investigation, Driftwood Bay, Umnak Island, Alaska (2018) Radiocarbon, Cesium-137, Grain Size, and X-ray Fluorescence Data for Tsunami Geology Investigation, Driftwood Bay, Umnak Island, Alaska (2018)
This dataset consists of nine tables that include radiocarbon dates, Cesium-137 activity, grain size measurements, and scanning X-ray fluorescence element intensity counts.
Filter Total Items: 26
No results found.
Filter Total Items: 57
Reproducibility and variability of earthquake subsidence estimates from saltmarshes of a Cascadia estuary Reproducibility and variability of earthquake subsidence estimates from saltmarshes of a Cascadia estuary
We examine fossil foraminiferal assemblages from 20 sediment cores to assess sudden relative sea-level (RSL) changes across three mud-over-peat contacts at three salt marshes in northern Humboldt Bay, California (~44.8°N, -124.2°W). We use a validated foraminiferal-based Bayesian transfer function to evaluate the variability of subsidence stratigraphy at a range of 30-6000 m across an...
Authors
Jason Scott Padgett, Simon E. Engelhart, Harvey M. Kelsey, Robert C. Witter, Niamh Cahill
Unravelling a 2300 year long sedimentary record of megathrust and intraslab earthquakes in proglacial Skilak Lake, south-central Alaska Unravelling a 2300 year long sedimentary record of megathrust and intraslab earthquakes in proglacial Skilak Lake, south-central Alaska
Seismic hazards in subduction settings typically arise from megathrust, intraslab and crustal earthquake sources. Despite the frequent occurrence of intraslab earthquakes in subduction zones and their potential threat to communities, their long-term recurrence behaviour is barely studied. Sedimentary sequences in lakes may register ground shaking from different seismic sources. This...
Authors
Nore Praet, Maarten Van Daele, Jasper Moernaut, Thomas Mestdagh, Thomas Vandorpe, Britta J.L. Jensen, Robert C. Witter, Peter J. Haeussler, Marc De Batist
Changing impacts of Alaska-Aleutian subduction zone tsunamis in California under future sea-level rise 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...
Authors
Tina Dura, Andra Garner, Robert Weiss, Robert E. Kopp, Simon E. Engelhart, Robert C. Witter, Richard W. Briggs, Charles Mueller, Alan Nelson, Benjamin P. Horton
Geomorphic expression and slip rate of the Fairweather fault, southeast Alaska, and evidence for predecessors of the 1958 rupture Geomorphic expression and slip rate of the Fairweather fault, southeast Alaska, and evidence for predecessors of the 1958 rupture
Active traces of the southern Fairweather fault were revealed by light detection and ranging (lidar) and show evidence for transpressional deformation between North America and the Yakutat block in southeast Alaska. We map the Holocene geomorphic expression of tectonic deformation along the southern 30 km of the Fairweather fault, which ruptured in the 1958 moment magnitude 7.8...
Authors
Robert C. Witter, Adrian Bender, Katherine M. Scharer, Christopher DuRoss, Peter J. Haeussler, Richard O. Lease
A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis
A new history of great earthquakes (and their tsunamis) for the central and southern Cascadia subduction zone shows more frequent (17 in the past 6700 yr) megathrust ruptures than previous coastal chronologies. The history is based on along-strike correlations of Bayesian age models derived from evaluation of 554 radiocarbon ages that date earthquake evidence at 14 coastal sites. We...
Authors
Alan Nelson, Christopher DuRoss, Robert C. Witter, Harvey M. Kelsey, Simon E. Engelhart, Shannon A. Mahan, Harrison J. Gray, Andrea D. Hawkes, Benjamin P. Horton, Jason S. Padgett
Extreme Quaternary plate boundary exhumation and strike slip localized along the southern Fairweather fault, Alaska, USA Extreme Quaternary plate boundary exhumation and strike slip localized along the southern Fairweather fault, Alaska, USA
The Fairweather fault (southeastern Alaska, USA) is Earth’s fastest-slipping intracontinental strike-slip fault, but its long-term role in localizing Yakutat–(Pacific–)North America plate motion is poorly constrained. This plate boundary fault transitions northward from pure strike slip to transpression where it comes onshore and undergoes a 6–8 km/m.y. exhumation rates that increases in...
Authors
Richard O. Lease, Peter J. Haeussler, Robert C. Witter, Daniel F. Stockli, Adrian Bender, Harvey Kelsey, Paul O’Sullivan
Non-USGS Publications**
Engelhart, S. E., Horton, B. P., Nelson, A. R., Hawkes, A. D., Witter, R. C., Wang, K., Wang P.-L., and Vane, C. H., 2013, Testing the use of microfossils to reconstruct great earthquakes at Cascadia, Geology, doi:10.1130/G34544.1.
Engelhart, S. E., B. P. Horton, C. H. Vane, A. R. Nelson, R. C. Witter, S. R. Brody, and A. D. Hawkes, 2013, Modern foraminifera, δ13C, and bulk geochemistry of central Oregon tidal marshes and their application in paleoseismology, Palaeogeography, Palaeoclimatology, Palaeoecology, doi:10.1016/j.palaeo.2013.02.032.
Kelson, K., R. C. Witter, A. Tassara, I. Ryder, C. Ledezma, G. Montalva, D. Frost, N. Sitar, R. Moss, and L. Johnson, 2012, Coseismic tectonic surface deformation during the 2012 Maule, Chile, Mw 8.8 earthquake, Earthquake Spectra, v. 28, n. S1, p. 39-54.
Pilarczyk, J. E., Horton, B. P., Witter, R. C., Vane, C. H., Chagué-Goff, C., Goff, J., 2012, Sedimentary and foraminiferal evidence of the 2011 Tohoku-oki tsunami on the Sendai coastal plain, Japan. Sedimentary Geology. doi:10.1016/j.sedgeo.2012.08.011.
Richmond, B., W. Szczucinski, C.Chague-Goff, K. Goto, D. Sugawara, R. Witter, D.R. Tappin, B. Jaffe, S. Fujino, Y. Nishimura, and J. Goff, 2012, Erosion, deposition and landscape change on the Sendai coastal plain, Japan, resulting from the March 11, 2011 Tohoku-oki tsunami, Sedimentary Geology, doi:10.1016/j.sedgeo.2012.08.005.
Witter, R.C., Y.J. Zhang, K. Wang, C. Goldfinger, and G.R. Priest, 2012, Coseismic slip on the southern Cascadia megathrust implied by tsunami deposits in an Oregon lake and earthquake-triggered marine turbidites, Journal of Geophysical Research, 117, B10303, doi:10.1029/2012JB009404.
Allan, J., P. Komar, P. Ruggiero, and R.C. Witter, 2012, The March 2011 Tohoku tsunami and its impacts along the U.S. West Coast, Journal of Coastal Research, Journal of Coastal Research, v. 28, n. 5, p. 1142-1153, doi:10.2112/jcoastres-d-11-00115.1.
Witter, R. C., B. Jaffe, Y. Zhang, and G. R. Priest, 2012, Reconstructing Hydrodynamic Flow Parameters of the 1700 Tsunami at Cannon Beach, Oregon, USA, Natural Hazards, doi:10.1007/s11069-011-9912-7.
Horton, B. P., Sawai, Y., Hawkes, A. D., and Witter, R. C., 2011, Sedimentology and paleontology of a tsunami deposit accompanying the great Chilean earthquake of February 2010: Marine Micropaleontology, v. 79, no. 3-4, p. 132–138, doi:10.1016/j.marmicro.2011.02.001
Zhang, Y. J., R. C. Witter, and G. R. Priest, 2011, Tsunami-tide interaction in 1964 Prince William Sound tsunami, Ocean Modelling, v. 40, p. 246–259, doi:10.1016/j.ocemod.2011.09.005
**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.