Alaska Earthquake and Tsunami Hazards
Science Center Objects
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 Nation. The Alaska Earthquake and Tsunami Hazards team conducts field-based research to understand how, where, and why earthquakes and tsunamis occur in Alaska. Our research examines earthquake hazards that contribute to societal risk in Alaska and beyond, including earthquake ground motion, fault slip, surface deformation, landslides and liquefaction triggered by strong ground shaking, and tsunamis.
Debris avalanches on bluffs composed of glacial outwash sediment along the Eklutna River.
(Credit: Rob Witter, U.S. Geological Survey. Public domain.)
Our research team examines major fault systems in Alaska capable of generating large earthquakes, including the Alaska-Aleutian subduction zone, the Denali Fault system, and the Queen Charlotte-Fairweather Fault system. Many active faults in Alaska are capable of generating large tsunamis that threaten coastal communities in Alaska and beyond. For example, seafloor deformation during historic Alaska-Aleutian subduction zone earthquakes has generated tsunamis that traveled across the Pacific Ocean and impacted densely populated coasts around the Pacific Rim including Hawaii and the mainland U.S. west coast. The Denali Fault and other active faults in Alaska encroach on populated areas and critical infrastructure, including existing and proposed oil and natural gas pipelines. Our investigation of these fault systems reveals the location, magnitude, and frequency of prehistoric earthquakes and tsunamis, and informs probabilistic assessments that forecast future hazards.
The Alaska Earthquake Hazards Project research equips Alaska and Pacific Rim stakeholders and communities with vital information to improve earthquake and tsunami resilience. Remote but fast-moving faults such as the Queen Charlotte-Fairweather Fault system represent scientific frontier areas, where study improves understanding of earthquake processes that occur on slower-moving faults near densely populated urban centers in the contiguous U.S.
Characterizing the Active Queen Charlotte-Fairweather Fault System
Alaska-Aleutian Subduction Zone Studies
Alaska Seismic Hazard Map
M7.1 November 30, 2018 Anchorage Earthquake
Recently Completed Research:
- Denali Fault Paleoseismology
- Denali Fault Slip Rate
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Date published: January 30, 2020Status: ActiveEarthquake Hazards in Southeastern Alaska
Over the last 100 years, the Queen Charlotte-Fairweather fault system has produced large-magnitude earthquakes affecting both Canada and the U.S. To fill in missing details about its offshore location and structure, USGS uses sophisticated techniques to truly understand the fault’s hazard potential.
Contacts: Danny Brothers -
Date published: November 5, 2019Status: ActiveM7.1 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: October 9, 2018Status: ActiveAlaska 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, 2018Status: ActiveAlaska-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, 2018Status: ActiveCharacterizing 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: April 26, 2018Status: ActiveHazards in Alaska
A major goal of the U.S. Geological Survey (USGS) is to reduce the vulnerability of the people and areas most at risk from natural hazards. Working with partners throughout all sectors of society, the USGS provides information, products, and knowledge to help build more resilient communities. This site provides important links to a number of hazard related internet sites that provide important...
Attribution: Region 11: Alaska, Alaska Science Center
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.
The 30 November 2018 Mw7.1 Anchorage Earthquake
The Mw">Mw 7.1 47 km deep earthquake that occurred on 30 November 2018 had deep societal impacts across southcentral Alaska and exhibited phenomena of broad scientific interest. We document observations that point to future directions of research and hazard mitigation. The rupture mechanism, aftershocks, and deformation of the...
West, Michael E.; Bender, Adrian; Gardine, Matthew; Gardine, Lea; Gately, Kara; Haeussler, Peter; Hassan, Wael; Meyer, Franz; Richards, Cole; Ruppert, Natalia; Tape, Carl; Thornley, John; Witter, Robert 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. Neotectonics of interior Alaska and the late Quaternary slip rate along the Denali fault system
The neotectonics of southern Alaska (USA) are characterized by a several hundred kilometers–wide zone of dextral transpressional that spans the Alaska Range. The Denali fault system is the largest active strike-slip fault system in interior Alaska, and it produced a Mw 7.9 earthquake in 2002. To evaluate the late Quaternary slip rate on the...
Haeussler, Peter J.; Matmon, Ari; Schwartz, David P.; Seitz, Gordon G.
Eastern Denali Fault surface trace map, eastern Alaska and Yukon, Canada
We map the 385-kilometer (km) long surface trace of the right-lateral, strike-slip Denali Fault between the Totschunda-Denali Fault intersection in Alaska, United States and the village of Haines Junction, Yukon, Canada. In Alaska, digital elevation models based on light detection and ranging and interferometric synthetic aperture radar data...
Bender, Adrian M.; Haeussler, Peter J. Alternative source models of very low frequency events
We present alternative source models for very low frequency (VLF) events, previously inferred to be radiation from individual slow earthquakes that partly fill the period range between slow slip events lasting thousands of seconds and low-frequency earthquakes (LFE) with durations of tenths of a second. We show that VLF events may emerge from...
Gomberg, Joan S.; Agnew, D.C.; Schwartz, S.Y. 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. 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. Intertidal 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...
Haeussler, Peter J.; Witter, Robert C.; Wang, Kelin Focused exhumation along megathrust splay faults in Prince William Sound, Alaska
Megathrust splay faults are a common feature of accretionary prisms and can be important for generating tsunamis during some subduction zone earthquakes. Here we provide new evidence from Alaska that megathrust splay faults have been conduits for focused exhumation in the last 5 Ma. In most of central Prince William Sound, published and new...
Haeussler, Peter J.; Armstrong, Phillip A; Liberty, Lee M; Ferguson, Kelly M; Finn, Shaun P; Arkle, Jeannette C; Pratt, Thomas L. Testing the use of bulk organic δ13C, δ15N, and Corg:Ntot ratios to estimate subsidence during the 1964 great Alaska earthquake
During the Mw 9.2 1964 great Alaska earthquake, Turnagain Arm near Girdwood, Alaska subsided 1.7 ± 0.1 m based on pre- and postearthquake leveling. The coseismic subsidence in 1964 caused equivalent sudden relative sea-level (RSL) rise that is stratigraphically preserved as mud-over-peat contacts where intertidal silt...
Bender, Adrian M.; Witter, Robert C.; Rogers, Matthew Little 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...
Witter, Robert C.; Briggs, Richard W.; Engelhart, Simon E.; Gelfenbaum, Guy R.; Koehler, Richard D.; Barnhart, William D.-
Date published: December 2, 2019Did You Feel It?
Feel an earthquake? Report it here. View reported earthquakes in your area.
Attribution: Earthquake Hazards Program
Evidence of turbidity currents in Eklutna Lake
USGS scientists, working with researchers from the University of Ghent, probed the floor of Eklutna Lake, Anchorage Borough, Alaska, for evidence of turbidity currents triggered by strong shaking during the 2018 Mw7.1 Anchorage earthquake. In this photo, USGS scientist Peter Haeussler points to a dark layer at the top of a sediment core taken from the floor of Eklutna Lake
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Queen Charlotte-Fairweather Fault Study Area
Queen Charlotte-Fairweather Fault study area offshore the west coast of Canada, and Southeast Alaska . A: Red line is the QueenCharlotte-Fairweather Fault. Box indicates area of map C. B. Location map. C. Water depths offshore in study area.
2018 Potter Hill landslide 2, Anchorage, AK
Landslide from bluff below rail grade north of Rabbit Creek. Main scarp of slump/flow slide at Potter Hill. Railroad grade is to the left, tidal flat to the right. Note ponded drainage and disrupted slide material.
2018 Anchorage Earthquake
Chugiak extensional cracks, Chugiak, AK
Extensional cracking and settling around private residence in Chugiak.
2018 Anchorage Earthquake
Ground crack at Sunset Park, Anchorage, AK
Crack observed in 2018 along headscarp of 1964 Government Hill landslide.
2018 Anchorage Earthquake
2018 Anchorage Earthquake -- Overflight Photo 5 - 12/03/18
Ground cracks present the potential for future slope failure during aftershocks or heavy rainfall. These cracks occur at the top of a steep valley wall on the south side of Potter Creek in south Anchorage.
2018 Anchorage Earthquake -- Overflight Photo 4 - 12/03/18
Sediment vented by earthquake-triggered liquefaction at the mouth of the Little Susitna River.
2018 Anchorage Earthquake -- Overflight Photo 3 - 12/03/18
Debris avalanches on bluffs composed of glacial outwash sediment along the Eklutna River.
2018 Anchorage Earthquake -- Overflight Photo 2 - 12/03/18
Complex earthflow slumping along Alaska Railroad overlooking tidal flats along Knik Arm near Mirror Lake. Failure of these low bluffs may have involved liquefaction.
2018 Anchorage Earthquake -- Overflight Photo 1 - 12/03/18
Lateral spreading disruptured Vine Road near Wasilla. Many failures of engineered materials occurred on or adjacent to saturated lowlands filled with organic sediment, silt, or sand.
Eagle River landslides, Eagle River, AK
Superficial slides along Eagle River east of Eagle River Loop Road.
2018 Anchorage Earthquake
Eklutna Dam after 2018 Anchorage earthquake
Eklutna Lake dam appeared to be undamaged the day after the earthquake; overflights of the lake showed no landslides impacted the lake shoreline.
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Date published: November 30, 20182018 Anchorage Earthquake
A magnitude 7.0 earthquake struck north of Anchorage, Alaska, on November 30, 2018, at 8:29 a.m. local time (17:29:28 UTC). For the most up-to-date information, please visit the USGS event page, and for estimates of casualties and damage, visit the USGS Prompt Assessment of Global Earthquakes for Response (PAGER) website.
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Date published: August 6, 2018Scientists complete mission to map fast-moving fault off Alaska: Data will help coastal communities prepare for risks from earthquakes and tsunamis
Researchers from NOAA, U.S. Geological Survey and their partners have completed the first high-resolution, comprehensive mapping of one of the fastest moving underwater tectonic faults in the world, located in southeastern Alaska. This information will help communities in coastal Alaska and Canada better understand and prepare for the risks from earthquakes and tsunamis that can occur when faults suddenly move.
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Date published: March 12, 2018Laboratory collaboration to study earthquake hazards off southeast Alaska and western Canada
Studying the Queen Charlotte-Fairweather fault
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Date published: November 18, 2017Return 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, 2016Uncharted: 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
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Date published: April 30, 2014Can a Creeping Segment of the Alaska-Aleutian Subduction Zone Generate a Great Earthquake?
The coastal geology of Simeonof Island, the southeastern-most island in the Shumagin archipelago of the Aleutian Islands, suggests the region has not experienced a great megathrust earthquake in at least the past 3,400 years.
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Date published: March 27, 2014Prior Great Earthquakes Unveiled at the Western Edge of the 1964 Alaska Rupture
Ever since the great magnitude 9.2 earthquake shook Alaska 50 years ago today, scientists have suspected that the quake's rupture halted at the southwestern tip of Kodiak Island due to a natural barrier.
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Date published: March 20, 2014
The Science Behind the 1964 Great Alaska Earthquake and Tsunami
Why does the 1964 Great Alaska Earthquake Matter 50 Years Later? Scientific experts will talk about a half-century of scientific and monitoring advances triggered by the 1964 events.
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Date published: February 24, 2014The 1964 Great Alaska Earthquake and Tsunami
On March 27th, 1964, the second largest instrumentally recorded earthquake worldwide rocked southern Alaska for 4 to 5 minutes. In addition to the earthquake, the event triggered a major tsunami that caused casualties and damage from the Kodiak Islands to northern California.
Attribution: Region 11: Alaska