Researchers came to the conclusion that the mysterious crack which appeared in the ground six years ago in Michigan is likely and unusual geological “pop-up”.
This is a formation that normally occurs around quarries or in areas where glaciers have recently receded, the team explained.
Although this particularly pop-up lacks of either of those areas mentioned before, the team led by Wayne Pennington, dean of the College of Engineering at Michigan Tech, said the Menominee Crack could be a one-of-a-kind feature as far as they can tell.
“One of our reasons for publishing this was that in our search of the literature we could find no other mention of modern pop-ups that did not occur at something like the base of a quarry, where people had removed massive amounts of rock earlier,” explained Pennington.
The team of seismologists had to apply a technique called “seismic refraction”, so they could get a better look at the rock underneath the ridge and confirm it was indeed a pop-up. The seismic refraction measured the speed of seismic waves as they travel within layers of the earth, and at the same time it determined the different distances from the seismic source, as reported by Phys.org.
The pattern of refractions speeds was later found by the scientists. Those patterns seemed to be consistent with the intense bending and the fracturing of the rock. What could have been the cause of the pop-up? it’s a question that remained unanswered. However, the team later found that it could have been due to a recent removal of a double-trunked pine days before the event.
There is a 60 percent chance that the provided explanation is the right one, said Pennington. But, since there is no record that this event has ever happened before, and the reason for the pop-up being a large tree is such a small effect, the team continue to wonder whether the explanation could be something else.
Further study is needed to be sure of the strange geological occurrence, but this new study helps the community to be closer to a final conclusion, explained the seismologists as the announced the study published in the journal Seismological Research Letters.
Source: Phys.org