CHAMPION TOWNSHIP, Ohio -- David Hacker, Ph.D., associate professor of geology at Kent State University at Trumbull, and two colleagues discovered and mapped the scope of the Markagunt slide over the past two summers. The Markagunt gravity slide, the size of three Ohio counties, is one of the two largest known continental landslides (larger slides exist on the ocean floors).

The catastrophic landslide, one of the largest known on the surface of the Earth, took place within minutes in southwestern Utah more than 21 million years ago. Hacker reports on his findings in a paper published in the November issue of the journal Geology.

His colleagues and co-authors are Robert F. Biek of the Utah Geological Survey and Peter D. Rowley of Geologic Mapping Inc. of New Harmony.

Geologists had known about smaller portions of the Markagunt slide before the recent mapping showed its enormous extent. Hiking through the wilderness areas of the Dixie National Forest and Bureau of Land Management land, Hacker identified features showing that the Markagunt landslide was much bigger than previously known.

The landslide took place in an area between what is now Bryce Canyon National Park and the town of Beaver, Utah. It covered about 1,300 square miles, an area as big as Ohio’s Cuyahoga, Portage and Summit counties combined.

The Markagunt could prove to be much larger than the Heart Mountain slide, once it is mapped in greater detail. “Large-scale catastrophic collapses of volcanic fields such as these are rare but represent the largest known landslides on the surface of the Earth,” the authors write.

The length of the landslide -- over 55 miles -- also shows that it was as fast moving as it was massive, Hacker said. Evidence showing that the slide was catastrophic -- occurring within minutes -- include the presence of pseudotachylytes, rocks that were melted into glass by the immense friction. Any animals living in its path would have been quickly overrun.

Evidence of the slide is not readily apparent to visitors today. “Looking at it, you wouldn’t even recognize it as a landslide,” Hacker noted.

Hacker, who studies catastrophic geological events, said the slide originated when a volcanic field consisting of many strato-volcanoes, a type similar to Mount St. Helens in the Cascade Mountains, which erupted in 1980, collapsed and produced the massive landslide. The collapse may have been caused by the vertical inflation of deeper magma chambers that fed the volcanoes. Hacker has spent many summers in Utah mapping geologic features of the Pine Valley Mountains south of the Markagunt where he has found evidence of similar, but smaller slides from magma intrusions called laccoliths.

While the Markagunt landslide was a rare event, it shows the magnitude of what could happen in modern volcanic fields like the Cascades. “We study events from the geologic past to better understand what could happen in the future,” Hacker said.

The next steps in the research, conducted with his co-authors on the Geology paper, will be to continue mapping the slide, collect samples from the base for structural analysis and date the pseudotachylytes.

Hacker, who earned his Ph.D. in geology at Kent State, joined the faculty in 2000 after working for an environmental consulting company. He is co-author of the book Earth’s Natural Hazards: Understanding Natural Disasters and Catastrophes, published in 2010.

Published by The Business Journal, Youngstown, Ohio.
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