The 2012 Haida Gwaii earthquake occurred just after . The shock had a

moment magnitude The moment magnitude scale (MMS; denoted explicitly with or Mw, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. It was defined in a 1979 pape ...

of 7.8 and a maximum

Mercalli Intensity The Modified Mercalli intensity scale (MM, MMI, or MCS), developed from Giuseppe Mercalli's Mercalli intensity scale of 1902, is a seismic intensity scale used for measuring the intensity of shaking produced by an earthquake. It measures the eff ...

of V (''Moderate''). The earthquake's epicentre was on

Moresby Island Moresby Island ( hai, Gwaii Haanas) is a large island () that forms part of the Haida Gwaii archipelago (formerly known as Queen Charlotte Islands) in British Columbia, Canada, located at . It is separated by the narrow Skidegate Channel from ...

of the

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 Heca ...

archipelago (formerly known as the Queen Charlotte Islands). This was the second largest Canadian earthquake ever recorded by a

seismometer A seismometer is an instrument that responds to ground noises and shaking such as caused by earthquakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The outpu ...

, after the

1949 Queen Charlotte Islands earthquake The 1949 Queen Charlotte Islands earthquake struck Haida Gwaii (at the time known as the Queen Charlotte Islands) and the Pacific Northwest coast at 8:01 p.m. PDT on August 21. The earthquake had a moment magnitude of 8.0 and a surface wav ...

, about away. One person died due to a car crash related to the tsunami in

Oahu Oahu () ( Hawaiian: ''Oʻahu'' ()), also known as "The Gathering Place", is the third-largest of the Hawaiian Islands. It is home to roughly one million people—over two-thirds of the population of the U.S. state of Hawaii. The island of O� ...

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...

Earthquake

Strong shaking was felt throughout Haida Gwaii where residents in

Masset Masset , formerly ''Massett'', is a village in Haida Gwaii in British Columbia, Canada. It is located on Masset Sound on the northern coast of Graham Island, the largest island in the archipelago, and is approximately west of mainland British Col ...

Skidegate Skidegate ( hai, Hlg̱aagilda) is a Haida community in in British Columbia, Canada. It is located on the southeast coast of Graham Island, the largest island in the archipelago, and is approximately west of mainland British Columbia across Hec ...

, Sandspit, and Queen Charlotte City were evacuated to higher ground. Minor shaking was felt in Prince Rupert and in other cities of the Interior such as Prince George, Quesnel, and as far away as Kamloops. Electricity service was interrupted in Bella Coola. USGS Shakemap - 2012 Haida Gwaii earthquake

USGS Shakemap - 2012 Haida Gwaii earthquake

Although the earthquake occurred on 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 ...

, a primarily strike-slip boundary between the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contine ...

and

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 Pacif ...

s where the Pacific Plate moves approximately north-northwest with respect to the North America plate at a rate of about 50 mm/yr, the 2012 quake exhibited a thrust mechanism, more characteristic of the

Cascadia Subduction Zone The Cascadia subduction zone is a 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, Juan de Fuca, a ...

to the south.

Tsunami

A tsunami warning was issued for the North American Coast from the

Alaskan Panhandle Southeast Alaska, colloquially referred to as the Alaska(n) Panhandle, is the southeastern portion of the U.S. state of Alaska, bordered to the east and north by the northern half of the Canadian province of British Columbia (and a small part ...

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 ...

, but later limited to the North Coast region of British Columbia. Canadian authorities were questioned for issuing a tsunami warning nearly 40 minutes after the U.S. had issued their warning. The greatest wave heights recorded at tide gauges in Canada were at

Langara Island Langara Island, known as Kiis Gwaii to the Haida ( Haida: ''Ḵ'íis Gwáayaay''), is the northernmost island of Haida Gwaii in British Columbia, Canada. The island is approximately in size. It is located approximately south of Alaska. Hist ...

and at

Winter Harbour Winter Harbour is the western-most settlement on the west coast about from the northwest tip of Vancouver Island, British Columbia. This unincorporated community on Winter Harbour is on the northern side of Quatsino Sound at the mouth. First Na ...

. In

Tofino Tofino ( ) is a town of approximately 2,516 residents on the west coast of Vancouver Island in the Canadian province of British Columbia. The District of Tofino is located at the western terminus of Highway 4 on the tip of the Esowista Peninsu ...

on Vancouver Island, the tsunami warning sirens were activated and residents in low-lying areas evacuated their homes. The maximum wave height recorded in Tofino was . Tofino's tsunami warning system was activated after communication with the provincial coordinating centre was cut off. In the U.S.,

was also placed on alert, and over 100,000 people were evacuated to higher ground. The maximum wave height recorded at tide gauges in Hawaii was . Other warnings were issued for the states of

Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. T ...

and

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

, but were subsequently lifted. Along the western coast of Haida Gwaii, the earthquake triggered tsunami waves with a maximum run-up height at 13 meters in Davidson Inlet. In Mike Inlet, the tsunami was measured at 7.6 meters, making it the largest tsunami generated by an earthquake in western Canadian history.

Damage

Despite the earthquake's large magnitude, no major structural damage was reported from any of the population centres in the vicinity. This can be explained by the remoteness of the tremor's epicentre. No casualties or major injuries were recorded from the quake, likely due to the sparsely populated nature of the region, but in

, one person died in a car crash near a road that was closed because of the tsunami threat near Oahu's northern coast. As a result of the earthquake and its aftershocks, the famed hot springs in Gwaii Haanas National Park on Hotspring Island dried up. In 2015 the hot springs began to come back.

Aftershocks

There were 94 aftershocks of magnitude 4.0 or greater lasting until November 7, as recorded by the USGS. The largest of these numerous aftershocks was a 6.3 magnitude earthquake that occurred to the west of the main tremor on the morning of October 28. This was followed on October 29 by a 6.2 aftershock to the south of the original quake. Four months after the mainshock, in January 2013, another magnitude 7.5 earthquake struck north of Haida Gwaii in southeastern Alaska. The earthquake had a pure strike-slip focal mechanism, consistent with a rupture along the Queen Charlotte Fault. This earthquake is not considered an aftershock, but was triggered by stress transfer caused by the October 2012 earthquake.

References

External links

* USGS
M7.7 - 139km S of Masset, Canada
2012-10-28 03:04:10 UTC * Natural Resources Canada
2012-10-27: M=7.7 - 74 km SSW of Queen Charlotte City, BC
Saturday October 27, 2012 * West Coast and Alaska Tsunami Warning Center
2012-10-28
* Pacific Tsunami Warning Center
Pacific archive
* Pacific Tsunami Warning Center
Hawaii archive
* tp://hazards.cr.usgs.gov/maps/sigeqs/20121028/20121028.pdf M7.7 Haida Gwaii region, Canada earthquake of 28 October 2012–

United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

Tsunami Animation: Haida Gwaii, Canada October 27, 2012
–

Pacific Tsunami Warning Center The Pacific Tsunami Warning Center (PTWC) is one of two tsunami warning centers that are operated by NOAA in the United States. Headquartered on Ford Island, HI, the PTWC is part of an international tsunami warning system (TWS) program and s ...

* {{Earthquakes in Canada Haida Gwaii earthquake

earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, fr ...

Earthquakes in British Columbia Tsunamis in the United States 2012 tsunamis October 2012 events in North America Haida Gwaii