Vancouver Island earthquake, 1946
| Vancouver Island earthquake, 1946 | |||
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| Coordinates | 49 ° 45 '36 " N , 125 ° 20' 24" W | ||
| date | June 23, 1946 | ||
| Time | 10:13:26 ( PDT ) | ||
| Magnitude | 7.3 M S | ||
| Strength | VII-VIII on the Mercalli scale | ||
| depth | 15 km | ||
| epicenter | Forbidden Plateau , Canada | ||
| country | Canada, United States |
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| Affected places |
Vancouver Island and part of the Pacific Northwest of the United States |
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| Tsunami | No | ||
| dead | 2 | ||
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The 1946 earthquake on Vancouver Island occurred with a magnitude of 7.3 on the magnitude scale and struck Vancouver Island off the Pacific coast of Canada on June 23, 1946 at 10:13 a.m. The epicenter was on the Forbidden Plateau northwest of Courtenay . While most of the major earthquakes in the Vancouver area occur on the boundary of the tectonic plate, the 1946 earthquake was a crust-related event. The tremors were felt from Portland, Oregon to Prince Rupert in northern British Columbia . It was one of the most devastating earthquakes in British Columbia's history, but the damage was limited in that there were no densely populated areas near the epicenter.
This earthquake was one of the largest in Canadian history. But the largest surely recorded was the earthquake off the Queen Charlotte Islands in 1949 , a so-called interplate earthquake , which occurred at the bottom of the ocean, directly on the rugged coast of Graham Island , and which had a magnitude of 8.1 on the moment magnitude Scale reached.
Background and tectonics
Little is known about the tectonics that caused the 1946 earthquake. No displacement of the earth's layers was found on the surface, most likely because the epicenter was in a region that was very remote and densely forested. A comprehensive study and computer simulation of seismic data from over 50 stations has shown that one possible explanation for the earthquake could be a fault corresponding to a mountain range on Vancouver Island known as the Beaufort Range . A fault that runs across Vancouver Island and corresponds to the extension of the submerged Nootka Fault on the coast of British Columbia is also a possible cause. But it is unlikely, as revealed in the earthquake no signs of Ausgleichungsbewegungen that (Iceland Highway called) or to other roads between Courtenay and along a number of roads that most of the eastern shoreline of Vancouver Iceland run Campbell River , would have to show. The depth of the earthquake is believed to be in the continental crust , and not on the edge of the Cascadia subduction zone , and not in the zone itself. For this specific reason, the epicenter was located somewhere in the Forbidden Plateau region of central Vancouver Island.
Damage and sacrifice
Although there was very large damage to property, the earthquake cost the relatively small number of two lives: Jacob L. Kingston, 69 years old, and Daniel Fidler, who was 50 years old. Kingston died of a heart attack, Fidler was in a boat that was hit by a wave.
In Vancouver there was damage to many tall buildings that oscillated violently, and a piece of brickwork at a train station collapsed. In addition, a gas pipeline broke within the city and several power outages occurred. Fires broke out at several chimneys and at least one of the suspension bridges was damaged by the vibrations. A fire broke out at the Vancouver Hotel, where elderly people were staying, leaving more than 500 families of war veterans to flee the flames. One writer, George Finley, reported that the Lions' Gate Bridge "swayed like a leaf" was accompanied by a "low, rumbling sound that sounded like a low growl."
The earthquake destroyed 75 percent of the chimneys in the communities of Cumberland , Union Bay and Courtenay and caused extensive damage in Comox , Port Alberni , and Powell River on the east side of the Strait of Georgia . Chimneys broke in Victoria , too , and fear so gripped the people of Victoria and Vancouver that some of them fled to the streets.
Landslides caused by the earthquake occurred across Vancouver Island. Ground subsidence, as well as aftermath of the earthquake, occurred most of the coastal areas of the Georgia Strait . This includes the Deep Bay plateau, which had plunged between 2.7 m and 25.6 m. These measurements were published by the Canadian Hydrographic Service. A three-meter-large shift in the ground on Read Island was also registered. Ships across the region were affected, and those who described the earthquake from a ship reported that some ships ran into sandbanks or hit rocks. Underground power lines were destroyed in the long and narrow Alberni Inlet and near the town of Powell River. All the lighthouse keepers in the surrounding area felt the earthquake and reported broken windows and broken dishes. A tsunami hit the west coast of Texada Island with two waves: the first was two meters high and the second was one meter. The earthquake caused a landslide near Mount Colonel Foster. Fortunately, the researchers were able to verify the effects of the earthquake: a trip to take aerial photographs had started shortly after the earthquake in 1946, and these photographs were eventually examined by a geoscientist in the late 1970s.
To the south of the Canadian-American border in Washington State , some chimneys fell over in East Sound on Orcas Island and a concrete factory was destroyed near Port Angeles . In Seattle there was some damage to the upper floors of tall buildings and a bridge was damaged. Strong shock waves from the quake were noted in Bellingham , Olympia , Raymond and Tacoma . The earthquake was strong enough to knock the needle on the University of Washington seismograph , and for a minute it did so in Seattle.
The earthquake caused significant movement in the structural layers of the earth. It moved a 91-meter wall 11 meters and moved the foundation of a house 1.5 meters. A total of approximately 260,000 km² was affected in Canada and the United States.
See also
Individual evidence
- ↑ a b c The M7.3 Vancouver Island Earthquake of 1946. Natural Resources Canada , March 11, 2019, accessed August 25, 2020 .
- ↑ Important Canadian Earthquakes. Natural Resources Canada , October 19, 2018, accessed August 25, 2020 .
- ↑ The M8.1 Haida Gwaii (formerly Queen Charlotte Islands) Earthquake of August 22, 1949. Natural Resources Canada , October 19, 2018, accessed August 25, 2020 .
- ^ WF Slawson, JC Savage: Geodetic deformation associated with the 1946 Vancouver Island, Canada, earthquake . In: Bulletin of the Seismological Society of America . tape 69 , no. 5 , October 1979, ISSN 0037-1106 , pp. 1487-1496 ( geoscienceworld.org ).
- ↑ a b c Damage Considerable In Coastal Area of Sunday Quake. on news.google.com
- ↑ a b c d e f g Angus M. Gunn: Encyclopedia of Disasters. Environmental Catastrophes and Human Tragedies . Greenwood Publishing Group, 2008, ISBN 978-0-313-08747-9 , pp. 399 .
- ↑ a b c d e f Washington State Earthquake History - Major earthquakes in Washington since 1880 (source: USGS). soundseismic.com, accessed October 17, 2016 .