A rare event took place this morning, an actual earthquake in Illinois. The Geology Professor at IVCC, Mike Phillips, says they happen here only about once every 5 to 10 years. They are rare because LaSalle County is not near a plate boundary, rather Northern Illinois is over the middle of a giant plate that rarely shifts in the middle.
12,000 years ago this part of Illinois was covered with about 2,000 feet of ice, and the Earth’s crust still reacts from time to time by the loss of the weight of that ice and pops occasionally from time to time.
Earthquakes are measured in two ways, by magnitude and by intensity.
The intensity is assigned a Roman numeral. Here is where listeners who experienced the quake can help seismologists. You can go to earthquake.usgs.gov and report what you experienced.
Most people in Putnam County report they were jolted awake, their bed did feel the quake.
Students in Phillips class reported it reminded them a lot of typical quarry blasts. We also heard a report it felt like a sonic boom when a military plane overhead breaks the sound barrier.
Though over 350 reports have been filed at the USGS website, Phillips cannot stress enough how important it is to file a report if you felt something while it’s still a fresh memory. This helps them to learn more about the intensity of this morning’s quake.