You're sound asleep on a cold, wintry night, and all of a sudden a loud boom wakes you up. A few things on your shelves rattle for a second or two, then all is silent.
Was it an earthquake? Maybe, but the real culprit is likely a frost quake, a geological phenomenon brought on by winter weather. Unlike earthquakes, frost quakes are non-tectonic seismic events, meaning they are not caused by the shifting of the Earth's tectonic plates.
Also known as cryoseisms, frost quakes are caused by a sudden rapid freezing of ground and bedrock, usually when temperatures go from above freezing to below zero.
As moisture absorbed in the rock and soil freezes, it expands. This puts a great amount of stress on the areas around it.
Eventually, the stress is too much and the soil and rock will crack in an "explosive" manner, creating a loud sound and even shaking the ground surface.
Since temperatures are coldest in the overnight hours, most people experience frost quakes in the middle of the night, often waking up because of them.
According to the Maine Geological Survey, frost quakes can even leave cracks in the ground.
Cryoseisms are often very localized events, but multiple quakes can happen over a particular area. This may explain why people in multiple counties in Indiana felt frost quakes in the early morning hours of Feb. 10, as reported by WTHR in Indianapolis.
Early morning lows were below zero across the state, as cold as 18 degrees below at Frankfort Airport. The NWS reported that the temperatures on Feb. 10 were the coldest seen in the state since January 2009.
The threat for potentially damaging thunderstorms will shift eastward across Europe through midweek.
Residents of the Philippines are being put on alert for potential impacts from Typhoon Noul, which will be a powerful typhoon when it approaches the Philippines this weekend.
While a few showers will pass east of the Bay Area, seasonable weather and sunshine will hold in place through the weekend.
Following a dip in temperature during the middle of the week, summerlike warmth will rebound across much of the Northeast by this weekend.
Daily episodes of severe thunderstorms and flooding downpours will impact the Plains this week, possibly lingering into the weekend.
Wind, seas and surf will build in advance of what could eventually become the first tropical system of 2015 along the southeastern Atlantic coast of the United States late this week.
Chicago, IL (1876)
Severe local windstorm resulted in $250,000 damage.
Lakehurst, NJ (1937)
Hindenburg disaster after 4-hour delay of landing due to a thunderstorm.
Omaha, NE (1975)
Massive tornado killed 3 people and injured 133 while causing 150 million dollars worth of damage. Tornado cut a swath 10 miles long and one-quarter of a mile wide through the industrial and residential areas of west-central Omaha before lifting over the northern section of the city. Most costly U.S. tornado to date.