Anyway yesterday morning he told me that at 11:15 after I had gone to sleep there was a loud sound like the front door slamming and the house shook. Yesterday morning I called our neighbor who we share a wall with to see if she was OK and she said it was probably an ice quake.
- An ice quake is caused by ice shifting on the lake. And is usually accompanied by loud cracking noises.
- It happens more often at night when the temperature changes are stronger.
- Apparently a lot of expansion and contraction happens out on the big ice sheets that cover Madison's lakes in winter. One of the most dramatic occurrences happened a little before noon on Jan.15, 1948, when seismographs measured a tremor at 3.8 on the Richter scale. The day after that tremor of 60 years ago, a group of geology students discovered "a four-foot overthrust in ice 1-1/2 feet thick.
I have generally been pretty oblivious to weather. That means I am rarely dressed correctly. But since moving here I am much more aware of the weather in general. And now I know about ice quakes.