Booming noises in the night could be frost quakes in the Twin Cities
Hearing loud cracks and booms in the middle of the night? Those eerie sounds could very well be frost quakes happening beneath the snow and ground.
"Has anyone experienced a 'Frost Quake' at their home this week? It sounded like something really big hit my house shaking the windows? I've lived here for 6 years and never had these happen until now," wrote Heidi Lynn in the Richfield community Facebook group.
Lynn's question has drawn dozens of replies from fellow Richfield residents hearing similar sounds.
"I've been hearing this sound for the past couple nights and it happens randomly in the middle of the night," a commenter replied. "I couldn't pin down where it was coming from but it sounds like a thud coming from outside the house."
Others said the booming sounds at night scared them, with one resident saying it sounded like a boulder hit her house while another said she ran outside with wasp spray after being alarmed by the noise.
The scientific term for a frost quake is cryoseism, which is the explosive release of expanding underground ice. It causes surrounding soil and rock to crack. All in all, they are quite uncommon in Minnesota.
"This is a fairly rare phenomenon up here and is more typical of areas in the eastern/northeastern US, however it does happen here occasionally," a National Weather Service official told Bring Me The News. "So while we cannot guarantee that these noises were frost quakes, it should certainly be considered one of the possibilities."
Frost quakes are most likely to be heard following rapid temperature drops, just like Minnesota had earlier this week when the temperature went from 42 Tuesday afternoon to 5 below Wednesday morning. But the NWS says conditions otherwise aren't ideal in the Twin Cities for frost quakes.
"A rapid fall to sub-zero temperatures is one of the key ingredients when it comes to this phenomenon which is conducive to what the last few days have been, however we also have a snowpack of around 4-6 inches that is typically detrimental as you want the cold to penetrate deep into the ground. We have also not had significant precipitation over the last week or so, which means if the sounds are related to a frost quake, it would be the result of ground water deep below the surface freezing which in turn leads to the noises as the ground shifts to compensate for the expanding ice, or alternatively a river or lake whose surface is frozen having subsurface liquid water freezing and causing cracks in the surface ice layer."
Unfortunately, hearing seismic activity related to frost quakes is possible but there isn't a way to confirm with 100% certainty that frost quakes are occurring, because they don't cause damage and only happen in a localized area.