Three geologists scramble down a hillside on Sedanka Island that overlooks Stardust Bay. The geologists documented driftlogs stranded at elevations up to 60 ft above sea level and over 0.5 mile inland.
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
Airborne Lidar-based Digital Elevation Models of Coastal Montague Island (Alaska) Acquired September 2018
Radiocarbon, Cesium-137, Grain Size, and X-ray Fluorescence Data for Tsunami Geology Investigation, Driftwood Bay, Umnak Island, Alaska (2018)
Digital Elevation Models of Glacier Bay National Park, Between Lituya Bay and Icy Point, Alaska, Derived from Airborne Lidar Data Acquired in September 2015
Three geologists scramble down a hillside on Sedanka Island that overlooks Stardust Bay. The geologists documented driftlogs stranded at elevations up to 60 ft above sea level and over 0.5 mile inland.
On a ridge behind Stardust Bay at an elevation of 46 feet above sea level, a shallow pit reveals five sand sheets deposited by tsunamis in the past 1700 years.
Location: Stardust Bay, Sendanka Island, Alaska
On a ridge behind Stardust Bay at an elevation of 46 feet above sea level, a shallow pit reveals five sand sheets deposited by tsunamis in the past 1700 years.
Location: Stardust Bay, Sendanka Island, Alaska
Scientists from the USGS and the University of Rhode Island examine coastal sediment on Simeonof Island for evidence of sudden land-level change caused by earthquakes on the Aleutian megathrust.
Scientists from the USGS and the University of Rhode Island examine coastal sediment on Simeonof Island for evidence of sudden land-level change caused by earthquakes on the Aleutian megathrust.
Geologists Search for Evidence of Ancient Beach Deposits and Uplifted Shorelines on Simeonof Island
linkScientists from the USGS, University of Rhode Island, and the Alaska Dept of Geological and Geophysical Surveys dig into coastal bluffs of Simeonof Island in search of evidence for ancient beach deposits and tectonically uplifted shorelines.
Geologists Search for Evidence of Ancient Beach Deposits and Uplifted Shorelines on Simeonof Island
linkScientists from the USGS, University of Rhode Island, and the Alaska Dept of Geological and Geophysical Surveys dig into coastal bluffs of Simeonof Island in search of evidence for ancient beach deposits and tectonically uplifted shorelines.
Scientists from the USGS, University of Rhode Island, and the Alaska Dept of Geological and Geophysical Surveys use a hand-driven corer to sample soils and marsh sediment on Simeonof Island as part of an investigation to investigate evidence for earthquakes and tsunamis in the Shumagin Islands.
Scientists from the USGS, University of Rhode Island, and the Alaska Dept of Geological and Geophysical Surveys use a hand-driven corer to sample soils and marsh sediment on Simeonof Island as part of an investigation to investigate evidence for earthquakes and tsunamis in the Shumagin Islands.
Palaeotsunamis in the Sino-Pacific region
Radiocarbon dating of tsunami and storm deposits
Ground failure triggered by shaking during the November 30, 2018, magnitude 7.1 Anchorage, Alaska, earthquake
Preface to the focus section on the 30 November 2018 Mw 7.1 Anchorage, Alaska earthquake
The sedimentary record of the 2018 Anchorage Earthquake in Eklutna Lake, Alaska: Calibrating the lacustrine seismograph
Ground failure from the Anchorage, Alaska, earthquake of 30 November 2018
Evidence for frequent, large tsunamis spanning locked and creeping parts of the Aleutian megathrust
Wetland stratigraphic evidence for variable megathrust earthquake rupture modes at the Cascadia subduction zone
New constraints on coseismic slip during southern Cascadia subduction zone earthquakes over the past 4600 years implied by tsunami deposits and marine turbidites
Microfossil measures of rapid sea-level rise: Timing of response of two microfossil groups to a sudden tidal-flooding experiment in Cascadia
Sculpted by water, elevated by earthquakes—The coastal landscape of Glacier Bay National Park, Alaska
Evidence for shallow megathrust slip across the Unalaska seismic gap during the great 1957 Andreanof Islands earthquake, eastern Aleutian Islands, Alaska
Non-USGS Publications**
**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.
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Filter Total Items: 15
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)
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.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. To be - Maps
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Filter Total Items: 26USGS Scientists Engaged in Field Work on the Aleutian IslandsUSGS Scientists Engaged in Field Work on the Aleutian Islands
Three geologists scramble down a hillside on Sedanka Island that overlooks Stardust Bay. The geologists documented driftlogs stranded at elevations up to 60 ft above sea level and over 0.5 mile inland.
Three geologists scramble down a hillside on Sedanka Island that overlooks Stardust Bay. The geologists documented driftlogs stranded at elevations up to 60 ft above sea level and over 0.5 mile inland.
Exposed Tsunami Sand Layers in a Pit Excavated by ScientistsExposed Tsunami Sand Layers in a Pit Excavated by ScientistsOn a ridge behind Stardust Bay at an elevation of 46 feet above sea level, a shallow pit reveals five sand sheets deposited by tsunamis in the past 1700 years.
Location: Stardust Bay, Sendanka Island, Alaska
On a ridge behind Stardust Bay at an elevation of 46 feet above sea level, a shallow pit reveals five sand sheets deposited by tsunamis in the past 1700 years.
Location: Stardust Bay, Sendanka Island, Alaska
Geologists Search for Signs of Tectonic Upheaval in a Marsh on Simeonof IslandGeologists Search for Signs of Tectonic Upheaval in a Marsh on Simeonof IslandScientists from the USGS and the University of Rhode Island examine coastal sediment on Simeonof Island for evidence of sudden land-level change caused by earthquakes on the Aleutian megathrust.
Scientists from the USGS and the University of Rhode Island examine coastal sediment on Simeonof Island for evidence of sudden land-level change caused by earthquakes on the Aleutian megathrust.
Geologists Search for Evidence of Ancient Beach Deposits and Uplifted Shorelines on Simeonof IslandGeologists Search for Evidence of Ancient Beach Deposits and Uplifted Shorelines on Simeonof IslandGeologists Search for Evidence of Ancient Beach Deposits and Uplifted Shorelines on Simeonof Island
linkScientists from the USGS, University of Rhode Island, and the Alaska Dept of Geological and Geophysical Surveys dig into coastal bluffs of Simeonof Island in search of evidence for ancient beach deposits and tectonically uplifted shorelines.
Geologists Search for Evidence of Ancient Beach Deposits and Uplifted Shorelines on Simeonof Island
linkScientists from the USGS, University of Rhode Island, and the Alaska Dept of Geological and Geophysical Surveys dig into coastal bluffs of Simeonof Island in search of evidence for ancient beach deposits and tectonically uplifted shorelines.
Geologists in Search of Tsunami Deposits on Simeonof IslandGeologists in Search of Tsunami Deposits on Simeonof IslandScientists from the USGS, University of Rhode Island, and the Alaska Dept of Geological and Geophysical Surveys use a hand-driven corer to sample soils and marsh sediment on Simeonof Island as part of an investigation to investigate evidence for earthquakes and tsunamis in the Shumagin Islands.
Scientists from the USGS, University of Rhode Island, and the Alaska Dept of Geological and Geophysical Surveys use a hand-driven corer to sample soils and marsh sediment on Simeonof Island as part of an investigation to investigate evidence for earthquakes and tsunamis in the Shumagin Islands.
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Filter Total Items: 46
Palaeotsunamis in the Sino-Pacific region
Palaeotsunami research in the Sino-Pacific region has increased markedly following the 2011 Tōhoku-oki tsunami. Recent studies encompass a variety of potential sources and cover a full range of research activities from detailed studies at individual sites through to region-wide data collation for the purposes of database development. We synthesise palaeotsunami data from around the region drawingAuthorsJames Goff, Robert C. Witter, James Terry, Michaela SpiskeRadiocarbon dating of tsunami and storm deposits
Radiocarbon age determinations can be an expedient and accurate means to assign age to deposits of tsunami or storm origin. Essential to the process of incorporating radiocarbon age determinations in tsunami or coastal storm investigations is an awareness on the part of the investigator that a sample will always return an age from a laboratory, but only carefully selected samples inform deposit agAuthorsHarvey M. Kelsey, Robert C. WitterGround 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 incipient landslides. This is not a complete inventAuthorsAlex R. R. Grant, Randall W. Jibson, Robert C. Witter, Kate E. Allstadt, Eric M. Thompson, Adrian M. BenderPreface to the focus section on the 30 November 2018 Mw 7.1 Anchorage, Alaska earthquake
On 30 November 2018, a magnitude (Mw) 7.1 intraslab earthquake occurred under the most densely populated area of Alaska, ∼12 km north of downtown Anchorage. It generated the strongest ground shaking in the greater Anchorage area since the 1964 Mw 9.2 Great Alaska earthquake. Although the 30 November 2018 earthquake did not cause deaths or serious injuries, its economical and psychological impacAuthorsNatalia Ruppert, Robert C. WitterThe sedimentary record of the 2018 Anchorage Earthquake in Eklutna Lake, Alaska: Calibrating the lacustrine seismograph
The 30 November 2018 Mw 7.1 Anchorage earthquake caused modified Mercalli intensities of V¼ to V½ at Eklutna Lake (south central Alaska). A few hours after the earthquake, a “dirt streak” was observed on the lake surface, followed by a peak in sediment turbidity values (∼80 times normal) at a drinking water facility, which receives water from the lake through a pipe. These observations hint towarAuthorsMaarten Van Daele, Peter J. Haeussler, Robert C. Witter, Nore Praet, Marc De BatistGround failure from the Anchorage, Alaska, earthquake of 30 November 2018
Investigation of ground failure triggered by the 2018 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 based on earthquake magnitude predict; this might result from the 2018AuthorsRandall W. Jibson, Alex R. R. Grant, Robert C. Witter, Kate E. Allstadt, Eric M. Thompson, Adrian BenderEvidence 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 descAuthorsRobert C. Witter, Richard W. Briggs, Simon E. Engelhart, Guy R. Gelfenbaum, Richard D Koehler, Alan R. Nelson, SeanPaul La Selle, Reide Corbett, Kristi L. WallaceWetland 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 the subduction zone has largely relied on relativeAuthorsAlan R. Nelson, Robert C. Witter, Simon Englehart, Andrea Hawkers, Benjamin P. HortonNew 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 tsunami deposits on land and marine turbidites offshoAuthorsGeorge R. Priest, Robert C. Witter, Yinglong J. Zhang, Chris Goldfinger, Kelin Wang, Jonathan C. AllanMicrofossil 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 foraminifera to restoration of a salt marsh in southAuthorsB. P. Horton, Yvonne Milker, T. Dura, Kelin Wang, W.T. Bridgeland, Laura S. Brophy, M. Ewald, Nicole Khan, S.E. Engelhart, Alan R. Nelson, Robert C. WitterSculpted 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 5 centimeters per year relative to the North AmeriAuthorsRobert C. Witter, Adam LeWinter, Adrian M. Bender, Craig Glennie, David C. FinneganEvidence 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 studies that labeled the area a seismic gap. Here, we sAuthorsD. J. Nicolsky, J.T. Freymueller, Robert C. Witter, E. N. Suleimani, R.D. KoehlerNon-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.2011.02.001Zhang, 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.
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