The 1870 Charlevoix earthquake occurred on 20 October in the Canadian province of

Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...

. It had a

moment magnitude The moment magnitude scale (MMS; denoted explicitly with or Mwg, 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. was defined in a 1979 paper ...

of 6.6 and a Modified Mercalli intensity rating of X (''Extreme''). The town of

Baie-Saint-Paul Baie-Saint-Paul (; 2021 Population 7,371; UA population 4,308) is a city in the Province of Quebec, Canada, on the northern shore of the St. Lawrence River. Baie-Saint-Paul is the seat of Charlevoix Regional County Municipality. The city i ...

was seriously damaged by the event, with the loss of six lives. Effects from the earthquake were felt as far as

Virginia Virginia, officially the Commonwealth of Virginia, is a U.S. state, state in the Southeastern United States, Southeastern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States between the East Coast of the United States ...

and along the

New England New England is a region consisting of six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York (state), New York to the west and by the ...

coast of the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

Tectonic setting

The Charlevoix Seismic Zone (CSZ) lies along the St. Lawrence River, northeast of Quebec City. Although eastern Canada has relatively infrequent earthquakes, due to its location away from active plate boundaries, the CSZ is its most active part, with five earthquakes of an estimated magnitude of 6 or greater since historical records began.

Focal mechanism The focal mechanism of an earthquake describes the Fault (geology)#Slip.2C heave.2C throw, deformation in the Hypocenter, source region that generates the seismic waves. In the case of a Fault (geology), fault-related event, it refers to the ori ...

s for earthquakes in this zone are consistent with rupture on both reverse and strike-slip faults. The main structures of the area are faults of the Saint Lawrence rift system that run parallel to the river, formed during the break-up of the

supercontinent In geology, a supercontinent is the assembly of most or all of Earth's continent, continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", ...

Rodinia Rodinia (from the Russian родина, ''rodina'', meaning "motherland, birthplace") was a Mesoproterozoic and Neoproterozoic supercontinent that assembled 1.26–0.90 billion years ago (Ga) and broke up 750–633 million years ago (Ma). wer ...

in the late

Neoproterozoic The Neoproterozoic Era is the last of the three geologic eras of the Proterozoic geologic eon, eon, spanning from 1 billion to 538.8 million years ago, and is the last era of the Precambrian "supereon". It is preceded by the Mesoproterozoic era an ...

and early

Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...

. The greatest seismicity occurs where the rift is overprinted by a ~300 Ma meteorite impact structure, the

Charlevoix impact structure The Charlevoix impact structure is a large eroded meteorite impact structure in the Charlevoix region of Quebec, Canada. Only part of the impact structure is exposed at the surface, the rest lying beneath the Saint Lawrence River. Description ...

. Most CSZ earthquakes have

hypocenter A hypocenter or hypocentre (), also called ground zero or surface zero, is the point on the Earth's surface directly below a nuclear explosion, meteor air burst, or other mid-air explosion. In seismology, the hypocenter of an earthquake is its ...

s within the Grenvillian

basement A basement is any Storey, floor of a building that is not above the grade plane. Especially in residential buildings, it often is used as a utility space for a building, where such items as the Furnace (house heating), furnace, water heating, ...

at depths between 7 and 15 km. Many of the smaller earthquakes do not appear to be located on the rift faults but within the volumes of rock between them. Larger events lie outside the impact structure and have inferred nodal planes consistent with reactivation of the rift faults. The relatively weak impact structure is interpreted to cause a perturbation of the regional stress field, affecting the stability of the rift faults. The estimated length of the most active portion of the CSZ is . The total fault area is determined to be .

Earthquake

The shallow-focus earthquake had an epicenter around the

Saint Lawrence River The St. Lawrence River (, ) is a large international river in the middle latitudes of North America connecting the Great Lakes to the North Atlantic Ocean. Its waters flow in a northeasterly direction from Lake Ontario to the Gulf of St. Lawrenc ...

. Its epicenter has been suggested to be in the southwestern end of the CSZ. A maximum Mercalli intensity of IX–X (''Violent–Extreme'') was assigned to Baie-Saint-Paul. In

Quebec City Quebec City is the capital city of the Provinces and territories of Canada, Canadian province of Quebec. As of July 2021, the city had a population of 549,459, and the Census Metropolitan Area (including surrounding communities) had a populati ...

, the intensity is estimated at VI (''Strong''). In

Old Montreal Old Montreal (, ) is a historic List of neighbourhoods in Montreal, neighbourhood within the List of municipalities in Quebec, municipality of Montreal in the province of Quebec, Canada. Home to the Old Port of Montreal, the neighbourhood is b ...

, strong to damaging (VI–VII) levels of shaking was observed. Researcher John E. Ebel and others calculated the intensity magnitude of the earthquake at 5.5–6.0, with 5.8 being the best estimate. Meanwhile, the

Geological Survey of Canada The Geological Survey of Canada (GSC; , CGC) is a Canadian federal government agency responsible for performing geological surveys of the country developing Canada's natural resources and protecting the environment. A branch of the Earth Science ...

and

U.S. Geological Survey The United States Geological Survey (USGS), founded as the Geological Survey, is an agency of the U.S. Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on March ...

earthquake catalogs placed the moment magnitude at 6.6 .

Damage

Two children lost their lives in the

Les Éboulements Les Éboulements () is a municipality (Quebec), municipality in the Capitale-Nationale region of Quebec, Canada. Its population centres include Les Éboulements (located along Quebec Route 362, Route 362 on the plateau overlooking the Saint Lawr ...

municipality in

Capitale-Nationale Capitale-Nationale (; ) is one of the 17 administrative regions of Quebec. It is anchored by the provincial capital, Quebec City, and is largely coextensive with that city's metropolitan area. It has a land area of 18,684.78 km2. It reported ...

. Four additional deaths were attributed to a

landslide Landslides, also known as landslips, rockslips or rockslides, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, mudflows, shallow or deep-seated slope failures and debris flows. Landslides ...

five days later. Despite the size and intensity of the quake, few deaths occurred due to the sparse population during the time of the quake.

Liquefaction In materials science, liquefaction is a process that generates a liquid from a solid or a gas or that generates a non-liquid phase which behaves in accordance with fluid dynamics. It occurs both naturally and artificially. As an example of t ...

occurred in the affected area. A landslide may have also occurred in the

Saguenay River __NOTOC__ The Saguenay River (, ) is a major river of Quebec, Canada. It drains Lac Saint-Jean in the Laurentian Highlands, leaving at Alma and running east; the city of Saguenay is located on the river. It drains into the Saint Lawrence River. ...

. Many homes in Les Éboulements were destroyed. Saint-Roch was severely damaged by the quake as well. Many chimneys were damaged in Lower Quebec City. In

Portland, Maine Portland is the List of municipalities in Maine, most populous city in the U.S. state of Maine and the county seat, seat of Cumberland County, Maine, Cumberland County. Portland's population was 68,408 at the 2020 census. The Portland metropolit ...

, the windows of buildings shattered. A rumbling sound was heard at

Albany, New York Albany ( ) is the List of capitals in the United States, capital city of the U.S. state of New York (state), New York. It is located on the west bank of the Hudson River, about south of its confluence with the Mohawk River. Albany is the oldes ...

, which lasted up to a minute. Clocks stopped in

Cleveland, Ohio Cleveland is a city in the U.S. state of Ohio and the county seat of Cuyahoga County, Ohio, Cuyahoga County. Located along the southern shore of Lake Erie, it is situated across the Canada–United States border, Canada–U.S. maritime border ...

. Reports of the earthquake's effects in

Dubuque, Iowa Dubuque (, ) is a city in Dubuque County, Iowa, United States, and its county seat. The population was 59,667 at the 2020 United States census. The city lies along the Mississippi River at the junction of Iowa, Illinois, and Wisconsin, a region ...

and

Richmond, Virginia Richmond ( ) is the List of capitals in the United States, capital city of the Commonwealth (U.S. state), U.S. commonwealth of Virginia. Incorporated in 1742, Richmond has been an independent city (United States), independent city since 1871. ...

have been taken with skepticism.

References

;Bibliography * {{Earthquakes in the United States 1870 natural disasters 1870 in Canada 1870 earthquakes Baie-Saint-Paul Earthquakes in Quebec 1870 in Quebec

Tectonic setting

Earthquake

Damage

See also

References