Magnitude 3.6 Earthquake near Montreal, Quebec.

Natural Resources Canada recorded a Magnitude 3.6 Earthquake at a depth of 18 km, about 39 km to the north of the city of Montreal in Quebec, slightly after 3.20 am local time (slightly after 7.20 am GMT) on Sunday 29 March 2020. There are no reports of any damage or injuries associated with this event, though it was felt across much of southern Quebec as well as in the US state of Vermont.

The approximate location of the 29 March 2020 Montreal Earthquake. USGS.

The quake took place within the Western Quebec Seismic Zone, an area of intraplate seismic activity underlying part of southwest Quebec and southeast Ontario. The precise cause of tectonic activity here is unclear, with different opinions being held by geologists in the area. The area is underlain by a number of ancient deep faults associated with ancient mountain-building episodes, though it is unclear how these relate to the quakes. Alternatively the activity may be related to the Great Meteor Hot Spot an area of magmatic upwelling that originates deep beneath the Earth's tectonic plates, and therefore moves separately of them. The hotspot is currently located to the south of the Azores, though it has been active for at least 125 million years, moving across southwest Canada and the eastern United States before crossing the Atlantic Ocean. Finally the events could be the result of glacial rebound; until about 10 000 much of northern North America was covered by a thick layer of glacial ice, which pushed the rocks of the lithosphere down into the underlying mantle. The ice as now long since melted, but the rocks are still springing back into their original position, causing the occasional Earthquake in the process.

 

Witness reports can help geologists to understand the processes going on in Earthquakes and the structures in the rocks that cause them. If you felt this quake you can report it to Natural Resources Canada here.

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Quebec Earthquake felt in New York, Vermont.

A Magnitude 4.4 Earthquake occurred at a depth of 9 km in southern Quebec, roughly 67 km northwest of Ottawa slightly before 9.45 am local time (slightly before 1.45 pm GMT) on Friday 17 May 2013, according to the United States Geological Survey. This is a large Earthquake for the region, and while no damage or injuries were recorded, it was felt as far away as New York and Vermont States.

The location of the 17 May 2013 Quebec Earthquake. Google Maps.

The quake took place within the Western Quebec Seismic Zone, an area of intraplate seismic activity underlying part of southwest Quebec and southeast Ontario. The precise cause of tectonic activity here is unclear, with different opinions being held by geologists in the area. The area is underlain by a number of ancient deep faults associated with ancient mountain-building episodes, though it is unclear how these relate to the quakes. Alternatively the activity may be related to the Great Meteor Hot Spot an area of magmatic upwelling that originates deep beneath the Earth's tectonic plates, and therefore moves separately of them. The hotspot is currently located to the south of the Azores, though it has been active for at least 125 million years, moving across southwest Canada and the eastern United States before crossing the Atlantic Ocean. Finally the events could be the result of glacial rebound; until about 10 000 much of northern North America was covered by a thick layer of glacial ice, which pushed the rocks of the lithosphere down into the underlying mantle. The ice as now long since melted, but the rocks are still springing back into their original position, causing the occasional Earthquake in the process.

See also Earthquake in southeast Missouri, Earthquake in eastern Kentucky, Quebec Earthquake, 27 August 2011, Earthquake in South Dakota, 9 August 2011 and Earthquakes on Sciency Thoughts YouTube.

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Industrialization of the East Canadian Tundra blamed for 90% drop in Caribou numbers.

Caribou (Rangifer tarandus), or reindeer as they are known in the Old World, are ubiquitous Arctic herbivores, found from Northern Scandinavia across the Russian Arctic, Alaska, the tundras of Northern Canada and in Western Greenland. A former population in Eastern Greenland, that some scientists believe to have been a separate subspecies, was driven extinct in the nineteenth century (Caribou taxonomy is not clear; there are clearly several subspecies, but different authorities do not agree on how they should be defined). They are widely domesticated, both for their meat, and as a beast of burden, and wild herds are hunted by indigenous peoples across much of the Arctic. Because of the widespread domestication of Caribou the species is not in danger of extinction, but wild herds have suffered sharp declines in numbers in recent decades, something that has been widely blamed on increased human activity in the Arctic.

A Caribou on the Tundra of Quebec.

A study for the human rights group Survival International released last month, found that the world's largest wild Caribou herd, the George River Herd, which roams across the tundras of northern Quebec and Labrador, has fallen from around 800 000 in 1993 to about 74 000, a loss of slightly over 90% of the population. The Canadian Government has also been monitoring the herd, and has recently introduced tougher restrictions on reindeer hunting in the area.

The study by Survival International, which concentrates on witness statements from Innu Tribal Elders, does not see hunting as the main reason for the George River Herd's decline, but rather suggests the herd may have been effected adversely by increasing industrialization in the area, particularly extraction of iron ore from the Labrador Trough, a geological feature that runs across Labrador and Quebec, by mining company Cap-Ex Ventures and the rising number of road-building and hydro-electric projects in the area.

While this initially sounds persuasive, Caribou populations are naturally prone to severe population fluctuations. As recently as 1950 the total Caribou population for Labrador and Quebec was estimated to be as low as 5000, divided into two herds, the George River and the Leaf. These fluctuations are thought to be caused by the grazing habits of the Caribou. In good times the population of Caribou grows steadily, till there are more Caribou than the environment can sustain, then overgraze their food supply, leading to widespread starvation and a general population crash. This then allows the environment to recover, whereupon the Caribou numbers start to rise again. This is bad for individual Caribou, but not necessarily a bad thing for the species, as the periodic crashes weed out less fit individuals and serve to keep down predator numbers, be they wolves or hunting permits.

Obviously reducing the total grazing are available will reduce the maximum population size the herd can reach, and therefore bring about the population crash sooner, but it does not necessarily follow that a dramatic crash in Caribou populations can be completely attributed to human activity.

See also The Western Black Rhino and the Vietnamese Rhino declared extinct, Greenpeace activists occupy the offices of Cairn Energy and Mammals on Sciency Thoughts Youtube.

Quebec Earthquake, 27 August 2011

At about 2.25 am on Saturday 27 August 2011, the Canadian province of Quebec suffered a minor earthquake. The quake measured 3.0 on the Richter Scale and occurred at a depth of about 12.8 km, just about large and shallow enough to have been felt, but unlikely to have caused any damage. The epicenter of the quake was about 40 km to the east of Quebec City.

Quebeck sits on the Canadian Shield, an ancient part of the North American Plate, and should in theory be very tectonically stable. Nevertheless it has two distinct earthquake zones, the Charlevoix Seismic Zone in the northeast and the Western Quebec Seismic Zone in the west, though this earthquake occurred in southeast of the state, outside of both zones. The mechanism behind this seismic activity is not well understood, but is being monitored and studied by the Canadian National Seismograph Network. It is thought that this activity is caused by stresses on the North American Plate resulting from the expansion of the Atlantic and the subduction zones along the Pacific Coast.

There has only ever been one death reported due to an earthquake in eastern Canada, that of a young girl in Montreal in 1732, and this report is considered dubious.

See also Virginia Earthquake shakes Washington, New York, Earthquake in South Dakota and Earthquakes on Sciency Thoughts YouTube.