The 2013 Craig, Alaska earthquake (also known as the Queen Charlotte Fault earthquake) struck on January 5, at 12:58 am ( UTC–7) near the city of Craig and

Hydaburg Hydaburg ( ) (''Higdáa G̱ándlaay'' in Haida) is a first-class city in the Prince of Wales-Hyder Census Area, in the U.S. state of Alaska. The population was 382 at the 2000 census and 376 as of the 2010 census. The name "Hydaburg" re ...

, on Prince of Wales Island. The 7.5 earthquake came nearly three months after an 7.8 quake struck

Haida Gwaii Haida Gwaii (; hai, X̱aaydag̱a Gwaay.yaay / , literally "Islands of the Haida people") is an archipelago located between off the northern Pacific coast of Canada. The islands are separated from the mainland to the east by the shallow Hec ...

on October 28, in 2012. The quake prompted a regional tsunami warning to

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost Provinces and territories of Canada, province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include ...

and

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S ...

, but it was later cancelled. Due to the remote location of the quake, there were no reports of casualties or damages.

Tectonic setting

The

Queen Charlotte Fault The Queen Charlotte Fault is an active transform fault that marks the boundary of the North American plate and the Pacific plate. It is Canada's right-lateral strike-slip equivalent to the San Andreas Fault to the south in California. The Queen Ch ...

is a major right-lateral (dextral)

strike-slip In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tecton ...

and

transform fault A transform fault or transform boundary, is a fault along a plate boundary where the motion is predominantly horizontal. It ends abruptly where it connects to another plate boundary, either another transform, a spreading ridge, or a subducti ...

running off the coast of British Columbia and into Southern Alaska, through the

Saint Elias Range The Saint Elias Mountains (french: Chaîne Saint-Élie) are a subgroup of the Pacific Coast Ranges, located in southeastern Alaska in the United States, Southwestern Yukon and the very far northwestern part of British Columbia in Canada. The range ...

for more than 700 miles. Its southernmost section joins a spreading ridge of the

Gorda Plate The Gorda Plate, located beneath the Pacific Ocean off the coast of northern California, is one of the northern remnants of the Farallon Plate. It is sometimes referred to (by, for example, publications from the USGS Earthquake Hazards Program) as ...

and the

Cascadia subduction zone The Cascadia subduction zone is a convergent boundary, convergent plate boundary that stretches from northern Vancouver Island in Canada to Northern California in the United States. It is a very long, sloping subduction zone where the Explorer ...

while the northern termination section joins the a

thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If ...

where the

Yakutat terrane The Yakutat Block is a terrane in the process of accreting to the North American continent along the south central coast of Alaska. It has been displaced about northward since the Cenozoic along the Queen Charlotte-Fairweather fault system. T ...

plows into the

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacifi ...

. It has been the source of several large earthquakes in the 20th century, and appears that much of its length has ruptured in these events. In 1949, it produced a magnitude 8.1 earthquake off the west coast of

, then in 1958 a magnitude 7.8 earthquake generated a

megatsunami A megatsunami is a very large wave created by a large, sudden displacement of material into a body of water. Megatsunamis have quite different features from ordinary tsunamis. Ordinary tsunamis are caused by underwater tectonic activity (movemen ...

more than 500 meters tall, killing five people. Other earthquakes in the region include a 7.6 near

Sitka russian: Ситка , native_name_lang = tli , settlement_type = Consolidated city-borough , image_skyline = File:Sitka 84 Elev 135.jpg , image_caption = Downtown Sitka in 1984 , image_size ...

, and the 2012 event. The Queen Charlotte Fault bears a similar resemblance with California's

San Andreas Fault The San Andreas Fault is a continental transform fault that extends roughly through California. It forms the tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip (horizontal) ...

, another transform fault to the south.

Earthquake

The rupture zone is situated on a

seismic gap A seismic gap is a segment of an active fault known to produce significant earthquakes that has not slipped in an unusually long time, compared with other segments along the same structure. There is a hypothesis or theory that states that over long ...

between fault segments which ruptured in 1972 to its north, and the other to the south in 1949. The largest earthquake prior to the 7.5 quake along this gap was a magnitude 6.8 to the south of the 2013 epicenter. The 2013 earthquake ruptured for a length of 150 km (93 mi), 322 km (200 mi) north of the 2012 event. A note to take into account, the 2012 temblor had a focal mechanism of thrust rather than strike-slip, like those observed along the fault. That earthquake was on the interface of the subducting Pacific Plate as it is underthrusted beneath the North American Plate. The Craig earthquake on the other hand, was a near pure strike-slip event which was probably in response to stress transfer from the quake four months ago.

Characteristic

Research found that the earthquake was a rare supershear event, and was the first of its kind to occur on an oceanic plate boundary. Supershear

rupture Rupture may refer to: General * Rupture (engineering), a failure of tough ductile materials loaded in tension Anatomy and medicine * Abdominal hernia, formerly referred to as "a rupture" * Achilles tendon rupture * Rupture of membranes, a "wate ...

initiated along the northern rupture zone for about 100 km with a velocity of 5.5 to 6.0 km/s, much faster that the propagation velocity of the S-waves. The rupture propagated northwards, away from the epicenter, with an initial rupture velocity of 3.0 km. This subshear rupture continued for the first 30 to 50 km. Afterward, the rupture velocity exceeded the S-wave propagation speed of 3.8 km/s, reaching 7.0 km/s through the upper crust at its highest.

Aftershocks

More than 290

aftershocks In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in the same area of the main shock, caused as the displaced crust adjusts to the effects of the main shock. Large earthquakes can have hundreds to thousand ...

greater than magnitude 2.5 were recorded in the aftermath of the earthquake from 2013 to 2020. Most of them were along other fault structures away from the main fault. This is also commonly seen in other supershear earthquakes. The largest aftershocks were of magnitude 5.9, 5.5 and 5.2 which occurred on a different fault from the mainshock.

Impact

A maximum intensity of V (''Moderate'') was felt in Craig,

, Klawock and

Hyder Hyder can refer to: Places *Hyder, Alaska, U.S. **Hyder Seaplane Base *Hyder, Arizona, U.S. ** Hyder Valley * Hyder Creek, is a river in New York, U.S. Other uses * Hyder (defunct company), a former Welsh utility company ** Hyder Consulting, a su ...

without damage, but there were reports of items falling off shelves. The earthquake was mildly felt as far away in

Seattle Seattle ( ) is a port, seaport city on the West Coast of the United States. It is the county seat, seat of King County, Washington, King County, Washington (state), Washington. With a 2020 population of 737,015, it is the largest city in bo ...

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

. A tsunami warning was broadcast from

Cape Fairweather Cape Fairweather is a cape in Antarctica that is high and is ice-covered except for rocky exposures along its southeast and east sides. It lies midway between Drygalski Glacier and Evans Glacier on the east coast of Graham Land and divides Norden ...

, Alaska to northern

Vancouver Island Vancouver Island is an island in the northeastern Pacific Ocean and part of the Canadian province of British Columbia. The island is in length, in width at its widest point, and in total area, while are of land. The island is the largest by ...

, while a tsunami advisory was issued to the coast of Washington. It was later canceled after no large waves were observed. The shock frightened many who fled to higher grounds to avoid the tsunami.

Tsunami

Because the earthquake was of almost pure strike-slip mechanism, only small waves were produced without damage. These waves were up to 14 cm high. Seiches up to 1.5 meters high were also recorded at Deer Lake, Alaska, north of Port Alexander. The small waves however, were not detected by

Ocean Networks Canada Ocean Networks Canada is a University of Victoria initiative that operates the NEPTUNE and VENUS cabled ocean observatories in the northeast Pacific Ocean and the Salish Sea. Additionally, Ocean Networks Canada operates smaller community-based ob ...

References

{{Earthquakes in Canada 2013 earthquakes Earthquakes in Canada Supershear earthquakes Earthquakes in Alaska 2013 tsunamis January 2013 events in Canada January 2013 events in the United States 2013 disasters in Canada 2013 in Alaska Strike-slip earthquakes