3.1 magnitude quake recorded in South Glens Falls, USGS says

SARATOGA COUNTY — An earthquake that was minor but large by upstate New York standards rattled dishes and residents’ nerves across the northern Capital Region at the crack of dawn Wednesday morning.

The quake, measuring a 3.1 magnitude, was centered in South Glens Falls but felt as far as 50 miles away, in what a geologist said was the fourth-largest earthquake since 1900 in a section of upstate where quakes are both rare and usually small.

John Garver, a geology professor at Union College in Schenectady, felt the quake at his home in West Glenville. “They’re uncommon, and the ones we have here are small,” he said Wednesday afternoon. “Of 26 earthquakes recorded in the Hudson Valley corridor since 1900, it was the fourth-largest.”

The Saratoga County Sheriff’s Department estimated it received around one hundred 911 emergency calls about the 6:43 a.m. event, which was felt throughout Saratoga County and beyond.

A 3.1 event is considered minor, “often felt by people, but very rarely causes damage. Shaking of indoor objects can be noticeable,” according to the USGS.

That fits with most accounts of the event residents posted on social media on Wednesday, as they remarked on the kind of event that is unusual but not unprecedented along the southern edge of the Adirondack Mountains.

“We were inundated with 911 calls from residents, pretty much throughout the county,” said Saratoga County Sheriff Michael H. Zurlo, who oversees the county’s emergency dispatching center. “Most of them were reporting a loud noise, some said their houses were rattling. As of this time, we have no report of injuries, but this was really concerning for a lot of people.”

Zurlo said he immediately got on social media and posted to the public that the event was a small earthquake, and to reserve the 911 line for emergencies. Despite the call volume, he said, “all the calls were answered.”

The USGS reporting system received reports from as far south as Rexford, and from locations in Fulton, Montgomery and Schenectady counties, as well as Warren and Washington counties.

The Montgomery County Sheriff’s Department also took to Facebook to acknowledge the tremor was felt there, but to report no indication of damage or injuries in Montgomery County.

The USGS reported the quake happened at a depth of 13.2 kilometers, or about 8.2 miles below ground.

Earthquaketrack.com reported it was the largest earthquake so far this year in New York state. The Northeastern U.S. in general isn’t known for its strong seismic activity, but local earthquakes aren’t unheard of.

“It was a small release of energy, probably on some unrecognized fault,” Garver said. “The current state geological map doesn’t have any recognized fault there, but there are a lot of unrecognized faults.”

Garver said what made Wednesday’s quake unusual is how widely it was felt, even though it was minor by international standards. “Here in the East it’s old, old crust, and it’s rigid. The seismic waves are rapidly transmitted because it’s like a rigid board,” he said. “In California, the crust is newer and softer, and it doesn’t transmit energy so far. They’re infrequent here, but when we have won, it’s widely felt.”

Gazette archives record that there was a 3.0 magnitude earthquake in the Albany County hill towns in 2010 that was felt over a wide area. In what scientists consider a different geological zone, there was a magnitude 5.2 earthquake centered near Ausable Forks in the Adirondacks in 2002.

Garver predicted there are likely to be aftershocks, but they will be so small as to be undetectable.