Hi, I'm Dave Thurlow for the Mount Washington Observatory and this is The Weather Notebook. Recently we here at the show heard examples of people reporting strange whomping sounds and seeing distant flashing lights, often followed by an earthquake.
Well, to find out what these folks were witnessing, we spoke with John Ebel, Director of Weston Observatory and a professor of geophysics at Boston College.
JE: Being here in the northeast, especially with northern New England being capable of getting very cold temperatures in the winter, there's a ground cracking phenomenon that feels and sounds very much like earthquake activity. We actually have a technical name for it. We call it cryoseisms.
A cryoseism? What the heck is a cryoseisms?
JE: They are literally the water in the soil in the ground freezing down to a deep enough depth that, of course as the freezing occurs, the water's expanding and as it freezes down into the earth, the expansion actually can cause the frozen ground to crack. And it seems like the cracking occurs very explosively, very suddenly. And when it does so, it can actually cause the ground to vibrate, cause a loud boom.
But what about the lights?:
JE: there are electrical changes that happen in rocks when they get squeezed. And of course earthquakes are really due to squeezing and then release of that pressure as the rock cracks and moves. And that can explain the earthquake light and lightning type effects that we see."
We have plenty of information about cryoseisms - and just about any other weather related phenomena on this and several other planets - at weathernotebook.org. Thanks go to Subaru, the beauty of all wheel drive.
Note on Cryoseisms