Was that an ‘ice quake?’ |
Valley News Dispatch

Was that an ‘ice quake?’

Mary Ann Thomas

The polar air and rapid freeze of the Northeast and Midwest has prompted reports of “frost quakes” or “ice quakes.”

Typically, the uncommon geological phenomenon characterized by a booming sound and caused by the sudden cracking of frozen soil or rock is reported in places like Alaska — not Dillsburg, Pennsylvania.

But a Dillsburg woman who was home crocheting a blanket this week was startled to hear a “big bang,” and could find no evidence of damage of anything falling at her home, according to the CBS television affiliate channel 21 in Harrisburg.

She had the good sense to call a local geologist who said it was likely a “frost quake,” one of number of local reports in York County.

The U.S. Geological Survey has heard about the recent spate of reports of frost quakes in the media, but they don’t really study them, according to Paul Caruso, a geophysicist at USGS, national earthquake information center in Golden, Colo.

“It’s not well known, and a lot of people haven’t heard of it,” he said of frost quakes. “A lot of study hasn’t gone into them because there isn’t significant damage.”

The booming sound of a “frost quake” is much like the sound of the cracking of an ice jam, which occurs when ice thawing and on the move.

The frost quake is highly localized, occurring where there is a lot of water in the soil and it freezes, transforming from a liquid to a solid and expanding causing the soils and water to “crack.”

“These are not events we would be concerned with causing significant damage like an earthquake,” Caruso said.

That’s because the energy released is not enough to cause damage and not big enough for USGS’ monitors to detect.

The regional office of the U.S. Army Corps of Engineers, Pittsburgh District, is not concerned about frost quakes. With its geologists and other professionals, the Corps monitors the integrity of federal public works such as 16 flood prevention reservoirs and 23 locks and dams in Pennsylvania, Ohio and West Virginia.

“We don’t see the conditions — soil or climate conditions – to damage our structures because of rapid freezing,” said Jeff Hawk, Corps spokesman.

“If we did see any heaves in the ground that are dramatic, we would do an inspection,” he added.

Mary Ann Thomas is a Tribune-Review staff writer. You can contact Mary Ann at 724-226-4691, [email protected] or via Twitter @MaThomas_Trib.