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.
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.
Biography
Research Focus
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.
Research Highlights
Mind the Gap: New Evidence for Alaskan Tsunamis Found
LiveScience reporter Becky Oskin highlights USGS findings that help fill gaps in Alaska’s earthquake and tsunami history.
Unknown Tsunami Trigger Hides Along a Creeping Aleutian Fault
EOS writer Cody Sullivan reviews USGS tsunami research published in Geophysical Research Letters.
Uncharted: Exploring one of America’s fastest faults
A team of USGS scientists spent 10 days in the wilderness investigating the Fairweather Fault.
Return to the Alaska Wilderness
USGS Scientists visit one of North America’s fastest-moving faults.
Education
BA in Biology, 1991, Whitman College, Walla Walla, WA
PhD in Geoscience, 1999, University of Oregon, Eugene, OR
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
Science and Products
Date published: November 5, 2019
Status: Active M7.1 November 30, 2018 Anchorage Earthquake
A magnitude 7.1 earthquake struck north of Anchorage, Alaska, on November 30, 2018, at 8:29 a.m. local time (17:29:28 UTC).
Attribution: Region 11: Alaska, Alaska Science Center
Date published: February 1, 2019
Status: Active Alaska Earthquake and Tsunami Hazards
Alaska has more large earthquakes than the rest of the United States combined. More than three-quarters of the state’s population live in an area that can experience a magnitude 7 earthquake. Our research provides objective science that helps stakeholders prepare for and mitigate the effects of future earthquakes and tsunamis, which bolsters the economic health and well-being of Alaska and the...
Attribution: Region 11: Alaska, Alaska Science Center
Date published: October 9, 2018
Status: Active Alaska Seismic Hazard Map
The National Seismic Hazard Maps developed by the USGS show the spatial probability of peak earthquake-driven ground motion levels. Since the last revisions to the map for Alaska in 2007, scientists have made significant advances in understanding active faulting, fault slip rates, and fault behavior.
Attribution: Region 11: Alaska, Alaska Science Center
Date published: October 9, 2018
Status: Active Alaska-Aleutian Subduction Zone Studies
Our research team is exploring seismic and aseismic slip along the Alaska-Aleutian arc and studying the prehistoric record of megathrust earthquakes and tsunamis along the Alaska-Aleutian subduction zone
Seismic and Aseismic Slip: Tectonic tremor and associated slow slip events represent a newly discovered part of the earthquake cycle. This research aims to...
Attribution: Region 11: Alaska, Alaska Science Center
Date published: October 9, 2018
Status: Active Characterizing the Active Queen Charlotte-Fairweather Fault System
This research aims to better characterize the earthquake potential of the southern Fairweather Fault in order to provide more accurate fault source data for the USGS National Seismic Hazard Map. Our approach interrogates lidar data and satellite imagery, applies paleoseismological methods to examine earthquake history, and leverages partnerships with USGS scientists from Colorado and...
Attribution: Region 11: Alaska, Alaska Science Center
Date published: June 5, 2018
Status: Active Margin-wide geological and geophysical synthesis to understand the recurrence and hazards of great subduction zone earthquakes in Cascadia
The Cascadia Subduction Zone, located in the U.S. Pacific Northwest and southwestern British Columbia, has hosted magnitude ≥8.0 megathrust earthquakes in the geologic past, a future earthquake is imminent, and the potential impacts could cripple the region. Subduction zone earthquakes represent some of the most devastating natural hazards on Earth. Despite substantial knowledge gained from...
Attribution: John Wesley Powell Center for Analysis and Synthesis
Date published: October 8, 2020
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.
Attribution: Alaska Science Center
Date published: January 1, 2018
Radiocarbon, Cesium-137, Grain Size, and X-ray Fluorescence Data for Tsunami Geology Investigation, Driftwood Bay, Umnak Island, Alaska (2018)
These files provide the complete data release for the paper entitled, "Frequent large tsunamis spanned locked/creeping parts of the Aleutian megathrust." The data set consists of nine tables that include radiocarbon dates, cesium-137 activity, grain size measurements, and scanning X-ray fluorescence element intensity counts.
Attribution: Alaska Science Center
Date published: January 1, 2017
Digital Elevation Models of Glacier Bay National Park, Between Lituya Bay and Icy Point, Alaska, Derived from Airborne Lidar Data Acquired in September 2015
This dataset provides four digital elevation models derived from airborne lidar data acquired over four separate areas along and adjacent to the Fairweather Fault along the remote Gulf of Alaska coast within Glacier Bay National Park. In 1958, the Fairweather Fault in southeast Alaska ruptured over 260 km between Yakutat Bay and Cross Sound, producing the magnitude 7.8 Lituya Bay earthquake....
Attribution: Alaska Science Center
Year Published: 2020
Identifying the greatest earthquakes of the past 2000 years at the Nehalem River Estuary, Northern Oregon Coast, USA
We infer a history of three great megathrust earthquakes during the past 2000 years at the Nehalem River estuary based on the lateral extent of sharp (≤3 mm) peat-mud stratigraphic contacts in cores and outcrops, coseismic subsidence as interpreted from fossil diatom assemblages and reconstructed with foraminiferal assemblages using a Bayesian...
Nelson, Alan R.; Hawkes, Andrea D.; Sawai, Yuki; Engelhart, Simon E.; Witter, Robert C.; Grant-Walter, Wendy C.; Bradley, Lee-Ann; Dura, Tina; Cahill, Niamh; Horton, Benajamin P.
Year Published: 2020
Ground failure triggered by shaking during the November 30, 2018, magnitude 7.1 Anchorage, Alaska, earthquake
We developed an initial inventory of ground failure features from the November 30, 2018, magnitude 7.1 Anchorage earthquake. This inventory of 153 features is from ground-based observations soon after the earthquake (December 5–10) that include the presence or absence of liquefaction, landslides, and individual crack traces of lateral spreads and...
Grant, Alex R. R. ; Jibson, Randall W.; Witter, Robert C.; Allstadt, Kate E.; Thompson, Eric M.; Bender, Adrian M.Attribution: Alaska Science Center, Earthquake Science Center, Natural Hazards, Earthquake Hazards Program, Region 11: Alaska
View Citation
Grant, A.R.R., Jibson, R.W., Witter, R.C., Allstadt, K.E., Thompson, E.M., and Bender, A.M., 2020, Ground failure triggered by shaking during the November 30, 2018, magnitude 7.1 Anchorage, Alaska, earthquake: U.S. Geological Survey Open-File Report 2020–1043, 21 p., https://doi.org/10.3133/ofr20201043.
Year Published: 2019
Ground failure from the Anchorage, Alaska, earthquake of 30 November 2018
Investigation of ground failure triggered by the 2018 Mw">MwMw 7.1 Anchorage earthquake showed that landslides, liquefaction, and ground cracking all occurred and caused significant damage. Shallow rock falls and rock slides were the most abundant types of landslides, but they occurred in smaller numbers than global models that are...
Jibson, Randall W.; Grant, Alex R. R. ; Witter, Robert C.; Allstadt, Kate; Thompson, Eric M.; Bender, Adrian
Year Published: 2019
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...
Witter, Robert C.; Briggs, Richard W.; Engelhart, Simon E.; Gelfenbaum, Guy R.; Koehler, Richard D; Nelson, Alan R.; La Selle, Seanpaul; Corbett, Reide; Wallace, Kristi L.
Year Published: 2018
Wetland stratigraphic evidence for variable megathrust earthquake rupture modes at the Cascadia subduction zone
Although widespread agreement that the Cascadia subduction zone produces great earthquakes of magnitude 8 to 9 was reached decades ago, debate continues about the rupture lengths, magnitudes, and frequency of megathrust earthquakes recorded by wetland stratigraphy fringing Cascadia’s estuaries. Correlation of such coastal earthquake evidence along...
Nelson, Alan R.; Witter, Robert C.; Englehart, Simon; Hawkers, Andrea; Horton, Benjamin P.Attribution: Geologic Hazards Science Center, Natural Hazards, Earthquake Hazards Program, Region 7: Upper Colorado Basin
View Citation
Wetland stratigraphic evidence for variable megathrust earthquake rupture modes at the Cascadia subduction zone, in Piscitelli, A., Milella, M., and Mastronuzzi, G., eds, Abstract volume for IGCP Project 639 - Sea-level change from minutes to millenia, Crossing southern Italy, a traveling meeting from Taranto to Siracusa, Italy 17-21 Sept 2018, p. 85-87.
Year Published: 2017
New constraints on coseismic slip during southern Cascadia subduction zone earthquakes over the past 4600 years implied by tsunami deposits and marine turbidites
Forecasting earthquake and tsunami hazards along the southern Cascadia subduction zone is complicated by uncertainties in the amount of megathrust fault slip during past ruptures. Here, we estimate slip on hypothetical ruptures of the southern part of the megathrust through comparisons of late Holocene Cascadia earthquake histories derived from...
Priest, George R.; Witter, Robert C.; Zhang, Yinglong J.; Goldfinger, Chris; Wang, Kelin; Allan, Jonathan C.Attribution: Alaska Science Center, Groundwater and Streamflow Information Program, Region 11: Alaska
View Citation
Priest, G.R., Witter, R.C., Zhang, Y.J., Goldfinger, C., Wang, K., and Allan, J.C., 2017, New constraints on coseismic slip during southern Cascadia subduction zone earthquakes over the past 4,600 years implied by tsunami deposits and marine turbidites: Natural Hazards, doi:10.1007/s11069-017-2864-9
Year Published: 2017
Microfossil measures of rapid sea-level rise: Timing of response of two microfossil groups to a sudden tidal-flooding experiment in Cascadia
Comparisons of pre-earthquake and post-earthquake microfossils in tidal sequences are accurate means to measure coastal subsidence during past subduction earthquakes, but the amount of subsidence is uncertain, because the response times of fossil taxa to coseismic relative sea-level (RSL) rise are unknown. We measured the response of diatoms and...
Horton, B.P.; Milker, Yvonne; Dura, T.; Wang, Kelin; Bridgeland, W.T.; Brophy, Laura S.; Ewald, M.; Khan, Nicole; Engelhart, S.E.; Nelson, Alan R.; Witter, Robert C.Attribution: Geologic Hazards Science Center, Natural Hazards, Earthquake Hazards Program, Region 7: Upper Colorado Basin
View Citation
B.P. Horton, Y. Milker, T. Dura, K. Wang, W.T. Bridgeland, L. Brophy, M. Ewald, N.S. Khan, S.E. Engelhart8,
A.R. Nelson, and R.C. Witter
Y. Milker;
T. Dura;
K. Wang;
W.T. Bridgeland;
L. Brophy;
M. Ewald;
N.S. Khan;
S.E. Engelhart;
A.R. Nelson;
R.C. Witter
Year Published: 2017
Sculpted by water, elevated by earthquakes—The coastal landscape of Glacier Bay National Park, Alaska
Within Glacier Bay National Park in southeastern Alaska, the Fairweather Fault represents the onshore boundary between two of Earth’s constantly moving tectonic plates: the North American Plate and the Yakutat microplate. Satellite measurements indicate that during the past few decades the Yakutat microplate has moved northwest at a rate of nearly...
Witter, Robert C.; LeWinter, Adam; Bender, Adrian M.; Glennie, Craig; Finnegan, DavidAttribution: Alaska Science Center, Groundwater and Streamflow Information Program, Region 11: Alaska
View Citation
Witter, R.C., LeWinter, A., Bender, A., Glennie, C., and Finnegan, D., 2017, Sculpted by water, elevated by earthquakes—The coastal landscape of Glacier Bay National Park, Alaska: U.S. Geological Survey General Information Product 177, https://doi.org/10.3133/gip177.
Year Published: 2016
Evidence for shallow megathrust slip across the Unalaska seismic gap during the great 1957 Andreanof Islands earthquake, eastern Aleutian Islands, Alaska
We reassess the slip distribution of the 1957 Andreanof Islands earthquake in the eastern part of the aftershock zone where published slip models infer little or no slip. Eyewitness reports, tide gauge data, and geological evidence for 9–23 m tsunami runups imply seafloor deformation offshore Unalaska Island in 1957, in contrast with previous...
Nicolsky, D. J.; Freymueller, J.T.; Witter, Robert C.; Suleimani, E. N.; Koehler, R.D.
Year Published: 2016
Differences in coastal subsidence in southern Oregon (USA) during at least six prehistoric megathrust earthquakes
Stratigraphic, sedimentologic (including CT 3D X-ray tomography scans), foraminiferal, and radiocarbon analyses show that at least six of seven abrupt peat-to-mud contacts in cores from a tidal marsh at Talbot Creek (South Slough, Coos Bay), record sudden subsidence (relative sea-level rise) during great megathrust earthquakes at the Cascadia...
Milker, Yvonne; Nelson, Alan R.; Horton, Benjamin P.; Engelhart, Simon E.; Bradley, Lee-Ann; Witter, Robert C.Attribution: Geologic Hazards Science Center, Natural Hazards, Earthquake Hazards Program, Region 7: Upper Colorado Basin
View Citation
Milker, Y., Nelson, A. R., Horton, B. P., Engelhart, S. E., Bradley, L-A, and
Witter, R. C., Differences in coastal subsidence in southern Oregon (USA)
during at least six megathrust earthquakes, Quaternary Science Reviews ,
v. 142, p. 143-163,
http://dx.doi.org/10.1016/j.quascirev.2016.04.017.
Year Published: 2016
Unusually large tsunamis frequent a currently creeping part of the Aleutian megathrust
Current models used to assess earthquake and tsunami hazards are inadequate where creep dominates a subduction megathrust. Here we report geological evidence for large tsunamis, occurring on average every 300–340 years, near the source areas of the 1946 and 1957 Aleutian tsunamis. These areas bookend a postulated seismic gap over 200 km long...
Witter, Robert C.; Carver, G.A.; Briggs, Richard W.; Gelfenbaum, Guy R.; Koehler, R.D.; La Selle, SeanPaul M.; Bender, Adrian M.; Engelhart, S.E.; Hemphill-Haley, E.; Hill, Troy D.
Year Published: 2015
Variability of intertidal foraminferal assemblages in a salt marsh, Oregon, USA
We studied 18 sampling stations along a transect to investigate the similarity between live (rose Bengal stained) foraminiferal populations and dead assemblages, their small-scale spatial variations and the distribution of infaunal foraminifera in a salt marsh (Toms Creek marsh) at the upper end of the South Slough arm of the Coos Bay estuary,...
Milker, Yvonne; Horton, Benjamin P.; Nelson, Alan R.; Engelhart, Simon E.; Witter, Robert C.Pre-USGS Publications
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.
Coseismic tectonic surface deformation during the 2012 Maule, Chile, Mw 8.8 earthquake
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
Date published: November 18, 2017
Return to the Alaska Wilderness: USGS Scientists visit one of North America’s fastest-moving faults
A team of USGS scientists spent two weeks in the isolated Glacier Bay National Park, exploring one of the fastest-moving faults in North America.
Attribution: Alaska Science Center
Date published: September 7, 2016
Uncharted: Exploring one of America’s fastest faults
A team of USGS scientists spent 10 days in the wilderness, exploring one of the fastest-moving faults in America