A mysterious crack opens up deep in Michigan Forest, as the scientists inform us. A strange and sudden buckling of the earth in Michigan five years ago is now being explained as a limestone bulge.
- Seismologists are studying a massive crack in the ground that appeared north of Menominee, Michigan in 2010
- The crack split the ground for 110 meters, and was as deep as 1.7 meters in some places.
- A team of scientists affirm that the crack is probably a ‘pop-up’ feature
- ‘Pop-ups’ develop in places where the earth rebounds after an overlying glacier shrinks away or when rock overburden is removed in a quarry
As many of you may already be aware of, to a geologist, a rock is not just a rock. Relying on that theory, a big crack in the ground is not what it first seems either.
One such split, north of Menominee, Michigan, in the state’s Upper Peninsula, is a large crack that formed in 2010. Not known for its earthquakes, Michigan is considered aseismic, and the Menominee Crack registered the Upper Peninsula’s first recorded earthquake measured at less than magnitude 1. The feature and its causes were mysterious.
Now, researchers from Michigan Technological University think they have identified what the feature is: a geological pop-up. The odd structure is often found at the base of quarries or where glaciers have recently receded. The team, led by Wayne Pennington, dean of the College of Engineering at Michigan Tech, says the Menominee Crack is a one-of-a-kind feature, as far as they can tell.
Scientists made the observation using a sledgehammer that was slammed into a metal ball on the ground, and then measured the sound waves to get a picture of the soil and rock layers below. They found a sharp buckle in the limestone where the crack was located.
Pennington stated in a declaration that ‘the crack itself was not as important to note as the ridge’, adding that the ridge indicated a deeper structure. He also affirmed that pop-ups usually form where downward pressure is lessened, most commonly at quarries and glacial zones where the overlying rock or ice has been removed.
One final clue was the loss, to lightning, of a giant white pine tree in the week before the crack appeared. ‘The timing is remarkable, and it leads us to be suspicious, but the tree weighed less than a fully loaded dump truck’, Pennington told Live Science.
All in all, the researchers admit that the cause of the crack remains a mystery but it also makes the feature unique.
The earth is still full of surprises. It’s just a little surprise, but it’s still interesting and we’re always learning more.
Image Source: phys.org