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TitleEarthquake Waves: The Damaging Cornwall, Ontario Earthquake of 1944
AuthorCassidy, J FORCID logo
SourceCanadian Association for Earthquake Engineering Newsletter vol. 7, issue 1, 2022 p. 1-2
Alt SeriesNatural Resources Canada, Contribution Series 20210522
PublisherCanadian Association for Earthquake Engineering
Mediapaper; on-line; digital
File formatpdf
ProvinceOntario; Quebec
NTS30; 31; 21E; 21L; 21M
Lat/Long WENS -80.0000 -70.0000 48.0000 40.0000
Subjectstectonics; earthquakes; seismic waves; earthquake damage; St. Lawrence Valley
Illustrationslocation maps
ProgramPublic Safety Geoscience Assessing Earthquake Geohazards
Released2022 01 01
AbstractCanada has remained quiet in terms of significant earthquakes during the past few months. As a result, this column will again highlight a significant historic Canadian earthquake - this one in eastern Ontario, near the St. Lawrence River. At 12:38 a.m. (Eastern time) on September 5, 1944, a damaging Mw5.8 earthquake occurred between Cornwall, Ontario and Massena, New York. Shaking was felt from Quebec City to Toronto to New York City to Lake Michigan (and most points in between). Pictures and dishes came crashing down, water pipes broke, plaster walls cracked and many cemetery headstones were rotated (these rotation patterns were later used to study the location and faulting style of this earthquake). This earthquake caused an estimated $10-15 million (2021 dollars) of damage in, and within ~50 km of Cornwall, ON (where about 2000 chimneys were damaged in this community of ~15,000 people at the time), and also caused significant damage in nearby Massena, New York (where 90% of the chimneys were damaged or destroyed). Substantial damage occurred at the Collegiate and Vocational School, a two-storey brick building in Cornwall. The out-of-plane failure of a top-floor unreinforced masonry wall was surprising, given the moderate magnitude (Mw5.8) of this earthquake, but a clear reminder of the risk (especially to older buildings) in the seismically active areas of eastern Canada. Modern studies of this earthquake revealed oblique thrust faulting (combination thrust and strike slip) at a depth of ~20 km. The faulting style is similar to smaller, recent earthquakes, and consistent with an ENE-oriented crustal stress field mapped in this region. There is also evidence of the significant role of local geology. Much of the damage coincided with structures built in areas underlain by the Leda Clay (ancient glacial lake sediments) of the St. Lawrence River valley. There were numerous impacts to these soft soils (e.g., fissures, liquefaction, water well effects - with some drying up and others overflowing) - a clear reminder of the importance of geological engineering here, and in all earthquake-prone regions. This earthquake was followed by numerous felt aftershocks, reminding us that the effects and impacts of a significant earthquake will last for days, weeks or sometimes months. For additional information on this earthquake, see Bruneau and Lamontagne (1994).
Summary(Plain Language Summary, not published)
This "Earthquake Waves" series of articles provides a reminder of significant earthquakes that have impacted Canada. This article summarises the damaging 1944 Cornwall, ON earthquake (Magnitude 5.8), including the effects on structures in the area, liquefaction observations, area that the earthquake was felt (across much of eastern Canada and the northeast US), aftershocks, and cause of this earthquake (crustal stresses).

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