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

Haida Gwaii Haida Gwaii (; / , literally "Islands of the Haida people"), previously known as the Queen Charlotte Islands, is an archipelago located between off the British Columbia Coast, northern Pacific coast in the Canadian province of British Columbia ...

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

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

and

Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...

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

Tectonic setting

The Queen Charlotte Fault 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 tectonic ...

and

transform fault A transform fault or transform boundary, is a fault (geology), fault along a plate boundary where the motion (physics), motion is predominantly Horizontal plane, horizontal. It ends abruptly where it connects to another plate boundary, either an ...

running off the coast of British Columbia and into Southern Alaska, through the Saint Elias Range for more than 700 miles. Its southernmost section joins a spreading ridge of the Gorda plate and the Cascadia subduction zone 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. I ...

where the Yakutat terrane plows into the North American plate. 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 an incredibly large wave created by a substantial and sudden displacement of material into a body of water. Megatsunamis have different features from ordinary tsunamis. Ordinary tsunamis are caused by underwater tectonic activi ...

more than 500 meters tall, killing five people. Other earthquakes in the region include a 7.6 near Sitka, 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 Fault (geology)#Strike-slip faults, right-lateral strike-slip transform fault that extends roughly through the U.S. state of California. It forms part of the tectonics, tectonic boundary between the Paci ...

, 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 initiated along the northern rupture zone for about 100 km with a velocity of 5.5 to 6.0 km/s, much faster than 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

aftershock In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in Epicenter, the same area of the Mainshock, main shock, caused as the displaced Crust (geology), crust adjusts to the effects of the main shock. Large earthq ...

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

Seattle Seattle ( ) is the most populous city in the U.S. state of Washington and in the Pacific Northwest region of North America. With a population of 780,995 in 2024, it is the 18th-most populous city in the United States. The city is the cou ...

, Washington. A tsunami warning was broadcast from Cape Fairweather, 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 ...

, 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.

Seiche A seiche ( ) is a standing wave in an enclosed or partially enclosed body of water. Seiches and seiche-related phenomena have been observed on lakes, reservoirs, swimming pools, bays, harbors, caves, and seas. The key requirement for formatio ...

s 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.

References

{{Earthquakes in Canada

Craig, Alaska Craig () is a city in the Prince of Wales-Hyder Census Area in the Unorganized Borough in the U.S. state of Alaska. The population was 1,036 at the 2020 census, down from 1,201 in 2010. Geography Craig is the largest town on Prince of Wale ...

Earthquakes in British Columbia Supershear earthquakes Earthquakes in Alaska Craig, Alaska earthquake Craig, Alaska earthquake Craig, Alaska earthquake Craig, Alaska earthquake Craig earthquake Strike-slip earthquakes