ROCHESTER, N.Y. -- A 5.1-magnitude earthquake in Ontario, Canada, was felt early Friday from upstate New York to the Vermont border.
Canada's government agency that monitors earthquakes says the quake occurred at 9:43 a.m. Friday about 13 miles northeast of Shawville, Quebec.
Media outlets in northern New York say people in communities along the St. Lawrence River and as far east as Lake Champlain on New York-Vermont border reported feeling their homes shake.
The United States Geological Survey put the reading lower, at 4.4. That reading was backed up by a different U.S. site, the Lamont-Doherty Earth Observatory at Columbia University in New York City. It is normal for it to take a while to determine a scientific consensus on the magnitude of an earthquake.
No injuries have been reported as a result of the tremor.
The epicenter was not far from the locus of a similarly sized earthquake felt in Rochester in June 2010.
The city's 911 dispatch center received a small handful of calls in the half hour after the earthquake.
"The State Office of Emergency Management continues to monitor effects of the earthquake that occurred this morning near Ottawa, Canada, and was felt throughout parts of New York State," read a statement from Gov. Andrew Cuomo's office. "At this time, there have been no reports of damage to any of the state's critical infrastructure."
Local residents reacted to the trembling on Twitter and other social networks.
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"I was sitting having my coffee about five minutes ago and the kitchen table started shaking," Louis Grande of Penfield, N.Y., said about 9:50 a.m.
Mike Giambrone, 48, was in his office in Perinton when he felt shaking.
"I was shaking and I looked at my desk and it was shaking," said Giambrone, who had never experienced an earthquake before. "It was weird. There was no hysteria. People were just like 'I think that was an earthquake.'"
Judy Dickinson of Irondequoit posted on Facebook that "my whole house shook, sounded like my roof was flying off and rolled me in my office chair!"
The area of western Quebec where Friday's quake was centered is well-known to earthquake experts.
"It's an area of persistent seismicity," Cindy Ebinger, professor of earth and environmental sciences at the University of Rochester. She said there had been foreshocks over the past week — smaller temblors that foreshadowed Friday's larger event.
Another quake of magnitude 5.0 occurred about 50 east of Shawville on June 23, 2010. That event was felt in western New York as well.
John Ebel, director of the Weston Observatory at Boston College, said the same seismic area was home to a magnitude 6.2 quake in 1935. That one caused the collapse of a railroad embankment and some structural damage.
Ebel said he wouldn't expect anything of that nature from Friday's event. "A magnitude 5 is right at the threshold at which damage starts. There could be chimney damage, cracked plaster, things being knocked off shelves. I would not expect anything major like building collapses."
Earthquakes generally result from movement at the intersection of two masses of rock deep underground.
The scenario most familiar to lay people is movement where two vast continental plates come together, as is the case at the famous San Andreas fault in California.
But according to information posted Friday morning on the website of the U.S. Geological Survey, the Western Quebec seismic zone is different. There are no plate boundaries there. Instead, the "seismic zone is laced with known faults, but numerous smaller or deeply buried faults remain undetected. Even the known faults are poorly located at earthquake depths.
"Accordingly, few, if any, earthquakes in the seismic zone can be linked to named faults. It is difficult to determine if a known fault is still active and could slip and cause an earthquake. As in most other areas east of the Rockies, the best guide to earthquake hazards in the Western Quebec seismic zone is the earthquakes themselves," the USGS post said.
In Burlington, Vt., the geologic shudder stirred social media from its otherwise routine Friday morning traffic.
