While New Zealand is scorched by a heatwave, frost quake explosions caused by a polar vortex are startling homeowners in the United States.
Temperatures have plummeted across the upper Midwest of America as a polar vortex, which AccuWeather describes as a larger pocket of very cold air, strikes the region.
While the public deals with the risk of frostbite, hypothermia, high heating costs and school closures, there is a lesser-known threat unsettling some residents.
Frost quakes, also known as cryoseisms, are a seismic event caused by a very sudden cracking of frozen soil or rock that has been saturated in water.
This happens when water which has drained into the land freezes and subsequently expands as it becomes ice. Stress placed on the ground by the expanding water eventually results in the land cracking, the ground shaking, and an explosion-like sound.
A frost quake in Pennsylvania startled local Dillsburg resident Michelle Tebbetts, reports Local 21 News.
"It sounded like a big piece of furniture fell over, and I'm thinking: what did the cats knock over that was that big and that louds," said Ms Tebbetts.
Local geologist Jeri Jones said there were multiple reports of an earthquake in the area, but he was fairly sure the loud noises and rattling had come from a frost quake.
"The ground and water will freeze and expand and it actually puts out a little explosion and people hear this booms," said Mr Jones.
Chastity Clark Baker said she was up all night because of frost quakes in Chicago, reports WGN9.
"I thought I was crazy... I was scared and thought it was the furnace," she said.
Newshub.
