A large crack formed in a hillside near the Altoona shopping center in the Logan Town, Pennsylvania, a couple of weeks ago. The crack is steadily growing since and has caused 52 local business in the area to shut temporarily on May 5, 2016.
Initially, the crack was about 0.3 m (1 foot) wide, but is now spreading across the width of about 3 m (10 feet) and is, locally, 4.6 m (15 feet) deep.
The local power supply to the shopping center was cut on May 4 and restored to most of the customers on the following day, according to the spokesman Scott Surgeoner.
According to Dr. Jennifer Sliko, a lecturer in earth sciences at Penn State Harrisburg, the crack was caused by the so-called “mass wasting” geological phenomenon, the particular form, such as this one being known as a “slump”.
“Basically, from what I can see from Google Earth and the video, when they built the town center, they cut into a hillside, over-steepening it. When you’re dealing with rock layers, you’re dealing with hundreds of thousands of years. This is a 4.6 m (15-foot) crack that formed in the last couple of days. That’s very fast, geologically speaking,” explained Sliko.
The shopping center in the area was built in 2006. The locally increased amounts of rainfall have probably lubricated the rock layers, and a part of the hillside tumbled, forming the large crack.
“The slope is readjusting itself. Once it gets to a lower incline where the friction of the particles is greater than the gravity pulling it down, it will stop moving,” said Sliko in response to a question of when will the crack stop growing.
Numerous experts are currently working on repairs on the slump. The repairs may include building retaining walls or drilling in vertical beams to stabilize the slope, according to the scientist’s expert opinion.
A high-quality video of the crack can be found here.
Featured image credit: weareCentralPA.com
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