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 understand the process generating tectonic tremor and its relationship to slow slip and earthquakes.
Paleoseismology and Paleotsunami: Despite being one of the most seismically active plate boundaries and the source of some of the largest historical earthquakes and tsunamis in the world, the earthquake prehistory of the Alaska-Aleutian subduction zone remains largely unstudied. Our research aims to reconstruct an accurate and comprehensive record of prehistoric Aleutian arc earthquakes and tsunamis to understand the frequency and origin of great earthquakes and damaging tsunamis sourced in the Aleutians. The findings from field campaigns in the Aleutians inform earthquake and tsunami hazard assessments that underpin the National Seismic Hazard Maps.
Return to Geology >> Hazards >> Alaska Earthquake and Tsunami Hazards
Exploring Seismic and Aseismic Slip in the Alaska-Aleutian Arc
Tectonic tremor, a weak vibration of the ground detectable only through sensitive seismometers, has been identified throughout south-central Alaska. This research uses the catalog of detected tremor to provide key constraints on fault conditions, plate boundary geometry and the relationship between tremor and slow slip. We investigate the spatial and temporal characteristics of tectonic tremor and slow slip phenomena in Alaska’s diverse tectonic environments, and relate it to earthquakes and slow slip in order to elucidate factors controlling tremor and complement similar studies in the contiguous United States.
Alaska-Aleutian Paleoseismology and Paleotsunami Studies
This research quantifies the timing, location, and size of large prehistoric earthquakes on upper-plate and plate-boundary faults, and the tsunamis that may accompany them, between Prince William Sound and the western Aleutians. We assess these parameters through comprehensive paleoseismology and paleotsunami studies at sites on the south-facing coasts of the Aleutian, Kodiak and Semidi Islands and the Patton Bay fault system in Prince William Sound. Fieldwork involves USGS scientists and academic collaborators. We develop histories of past earthquakes and tsunamis through extensive stratigraphic and geomorphic field studies, paleontologic analyses, tephrachronology, and radiometric dating. The paleoseismic and paleotsunami data we gather in the field ultimately contributes to the assessment of earthquake and tsunami hazards throughout western North America, including USGS National Seismic Hazard Maps and tsunami inundation maps developed through NOAA’s National Tsunami Hazard Mitigation Program.
Below are other science projects associated with this project.
Alaska Earthquake and Tsunami Hazards
Alaska Seismic Hazard Map
Characterizing the Active Queen Charlotte-Fairweather Fault System
Below are publications associated with this project.
Plateau subduction, intraslab seismicity, and the Denali (Alaska) volcanic gap
Paleoseismic potential of sublacustrine landslide records in a high-seismicity setting (south-central Alaska)
Evidence for shallow megathrust slip across the Unalaska seismic gap during the great 1957 Andreanof Islands earthquake, eastern Aleutian Islands, Alaska
Extending Alaska's plate boundary: tectonic tremor generated by Yakutat subduction
Unusually large tsunamis frequent a currently creeping part of the Aleutian megathrust
Tsunami recurrence in the eastern Alaska-Aleutian arc: A Holocene stratigraphic record from Chirikof Island, Alaska
Intertidal biological indicators of coseismic subsidence during the Mw 7.8 Haida Gwaii, Canada, earthquake
Beach ridges as paleoseismic indicators of abrupt coastal subsidence during subduction zone earthquakes, and implications for Alaska-Aleutian subduction zone paleoseismology, southeast coast of the Kenai Peninsula, Alaska
Little late Holocene strain accumulation and release on the Aleutian megathrust below the Shumagin Islands, Alaska
Uplift and subsidence reveal a nonpersistent megathrust rupture boundary (Sitkinak Island, Alaska)
- Overview
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 understand the process generating tectonic tremor and its relationship to slow slip and earthquakes.
Paleoseismology and Paleotsunami: Despite being one of the most seismically active plate boundaries and the source of some of the largest historical earthquakes and tsunamis in the world, the earthquake prehistory of the Alaska-Aleutian subduction zone remains largely unstudied. Our research aims to reconstruct an accurate and comprehensive record of prehistoric Aleutian arc earthquakes and tsunamis to understand the frequency and origin of great earthquakes and damaging tsunamis sourced in the Aleutians. The findings from field campaigns in the Aleutians inform earthquake and tsunami hazard assessments that underpin the National Seismic Hazard Maps.
Return to Geology >> Hazards >> Alaska Earthquake and Tsunami Hazards
Exploring Seismic and Aseismic Slip in the Alaska-Aleutian Arc
Tectonic tremor, a weak vibration of the ground detectable only through sensitive seismometers, has been identified throughout south-central Alaska. This research uses the catalog of detected tremor to provide key constraints on fault conditions, plate boundary geometry and the relationship between tremor and slow slip. We investigate the spatial and temporal characteristics of tectonic tremor and slow slip phenomena in Alaska’s diverse tectonic environments, and relate it to earthquakes and slow slip in order to elucidate factors controlling tremor and complement similar studies in the contiguous United States.
Alaska-Aleutian Paleoseismology and Paleotsunami Studies
This research quantifies the timing, location, and size of large prehistoric earthquakes on upper-plate and plate-boundary faults, and the tsunamis that may accompany them, between Prince William Sound and the western Aleutians. We assess these parameters through comprehensive paleoseismology and paleotsunami studies at sites on the south-facing coasts of the Aleutian, Kodiak and Semidi Islands and the Patton Bay fault system in Prince William Sound. Fieldwork involves USGS scientists and academic collaborators. We develop histories of past earthquakes and tsunamis through extensive stratigraphic and geomorphic field studies, paleontologic analyses, tephrachronology, and radiometric dating. The paleoseismic and paleotsunami data we gather in the field ultimately contributes to the assessment of earthquake and tsunami hazards throughout western North America, including USGS National Seismic Hazard Maps and tsunami inundation maps developed through NOAA’s National Tsunami Hazard Mitigation Program.
- Science
Below are other science projects associated with this project.
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...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.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 California... - Multimedia
- Publications
Below are publications associated with this project.
Plateau subduction, intraslab seismicity, and the Denali (Alaska) volcanic gap
Tectonic tremors in Alaska (USA) are associated with subduction of the Yakutat plateau, but their origins are unclear due to lack of depth constraints. We have processed tremor recordings to extract low-frequency earthquakes (LFEs), and generated a set of six LFE waveform templates via iterative network matched filtering and stacking. The timing of impulsive P (compressional) wave and S (shear) waAuthorsLindsay Yuling Chuang, Michael Bostock, Aaron Wech, Alexandre PlourdePaleoseismic potential of sublacustrine landslide records in a high-seismicity setting (south-central Alaska)
Sublacustrine landslide stratigraphy is considered useful for quantitative paleoseismology in low-seismicity settings. However, as the recharging of underwater slopes with sediments is one of the factors that governs the recurrence of slope failures, it is not clear if landslide deposits can provide continuous paleoseismic records in settings of frequent strong shaking. To test this, we selected tAuthorsNore Praet, Jasper Moernaut, Maarten Van Daele, Evelien Boes, Peter J. Haeussler, Michael Strupler, Sabine Schmidt, Michael G. Loso, Marc De BatistEvidence 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. KoehlerExtending Alaska's plate boundary: tectonic tremor generated by Yakutat subduction
The tectonics of the eastern end of the Alaska-Aleutian subduction zone are complicated by the inclusion of the Yakutat microplate, which is colliding into and subducting beneath continental North America at near-Pacific-plate rates. The interaction among these plates at depth is not well understood, and further east, even less is known about the plate boundary or the source of Wrangell volcanism.AuthorsAaron G. WechUnusually 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 where modern geodetic measurements indicate that the megAuthorsRobert C. Witter, G. A. Carver, Richard W. Briggs, Guy R. Gelfenbaum, R.D. Koehler, SeanPaul M. La Selle, Adrian M. Bender, S.E. Engelhart, E. Hemphill-Haley, Troy D. HillTsunami recurrence in the eastern Alaska-Aleutian arc: A Holocene stratigraphic record from Chirikof Island, Alaska
Despite the role of the Alaska-Aleutian megathrust as the source of some of the largest earthquakes and tsunamis, the history of its pre–twentieth century tsunamis is largely unknown west of the rupture zone of the great (magnitude, M 9.2) 1964 earthquake. Stratigraphy in core transects at two boggy lowland sites on Chirikof Island’s southwest coast preserves tsunami deposits dating from the postgAuthorsAlan R. Nelson, Richard W. Briggs, Tina Dura, Simon E. Engelhart, Guy Gelfenbaum, Lee-Ann Bradley, S.L. Forman, Christopher H. Vane, K.A. KelleyIntertidal biological indicators of coseismic subsidence during the Mw 7.8 Haida Gwaii, Canada, earthquake
The 28 October 2012 Mw 7.8 Haida Gwaii earthquake was a megathrust earthquake along the very obliquely convergent Queen Charlotte margin of British Columbia, Canada. Coseismic deformation is not well constrained by geodesy, with only six Global Positioning System (GPS) sites and two tide gauge stations within 250 km of the rupture area. To better constrain vertical coseismic deformation, we measurAuthorsPeter J. Haeussler, Robert C. Witter, Kelin WangBeach ridges as paleoseismic indicators of abrupt coastal subsidence during subduction zone earthquakes, and implications for Alaska-Aleutian subduction zone paleoseismology, southeast coast of the Kenai Peninsula, Alaska
The Kenai section of the eastern Alaska-Aleutian subduction zone straddles two areas of high slip in the 1964 great Alaska earthquake and is the least studied of the three megathrust segments (Kodiak, Kenai, Prince William Sound) that ruptured in 1964. Investigation of two coastal sites in the eastern part of the Kenai segment, on the southeast coast of the Kenai Peninsula, identified evidence forAuthorsHarvey M. Kelsey, Robert C. Witter, Simon E. Engelhart, Richard W. Briggs, Alan R. Nelson, Peter J. Haeussler, D. Reide CorbettLittle late Holocene strain accumulation and release on the Aleutian megathrust below the Shumagin Islands, Alaska
Can a predominantly creeping segment of a subduction zone generate a great (M > 8) earthquake? Despite Russian accounts of strong shaking and high tsunamis in 1788, geodetic observations above the Aleutian megathrust indicate creeping subduction across the Shumagin Islands segment, a well-known seismic gap. Seeking evidence for prehistoric great earthquakes, we investigated Simeonof Island, the arAuthorsRobert C. Witter, Richard W. Briggs, Simon E. Engelhart, Guy R. Gelfenbaum, Richard D. Koehler, William D. BarnhartUplift and subsidence reveal a nonpersistent megathrust rupture boundary (Sitkinak Island, Alaska)
We report stratigraphic evidence of land-level change and tsunami inundation along the Alaska-Aleutian megathrust during prehistoric and historical earthquakes west of Kodiak Island. On Sitkinak Island, cores and tidal outcrops fringing a lagoon reveal five sharp lithologic contacts that record coseismic land-level change. Radiocarbon dates, 137Cs profiles, CT scans, and microfossil assemblages arAuthorsRichard W. Briggs, Simon E. Engelhart, Alan R. Nelson, Tina Dura, Andrew C. Kemp, Peter J. Haeussler, D. Reide Corbett, Stephen J. Angster, Lee-Ann Bradley