Lake Mead water crisis is exposing volcanic rock from eruptions 12 million years ago - CNN

CNN  — 

Lake Mead’s falling h2o level has exposed respective shocking things successful caller months – previously sunken boats, old warfare ships and human remains. Now scientists are reporting a caller find connected Lake Mead’s adust bed: rocks laced with volcanic ash that rained down connected confederate Nevada during explosive eruptions astir 12 cardinal years ago.

The record-low h2o levels are exposing sedimentary rocks that haven’t been seen since the 1930s erstwhile the Hoover Dam was built and Lake Mead filled. Among these rocks, researchers with the University of Nevada successful Las Vegas recovered ash deposits from volcanoes successful Idaho, Wyoming and California.

“We knew that these ash units existed, but we were amazed to find truthful galore arsenic the Lake Mead h2o level lowered,” said Eugene Smith, an emeritus prof of geology astatine UNLV and co-author of the study.

The West’s clime change-fueled drought and overuse of the Colorado River’s h2o has pushed Lake Mead levels to unprecedented lows. As of September, the lake’s h2o level was conscionable 1,045 feet supra oversea level, oregon astir 27% of afloat capacity.

Scientists are taking vantage of the debased levels to survey sediment that hasn’t been exposed successful astir a century.

Smith’s probe squad recovered achromatic to grey colored volcanic ash weaving done the formerly submerged rocks. They took samples backmost to their laboratory to pinpoint the root of the ash, but it wasn’t from a azygous eruption.

They recovered grounds of respective volcanic blasts millions of years agone from places similar the Snake River Plain-Yellowstone country – a tract of inactive volcanoes that stretches crossed Idaho on the Snake River and into what is present Yellowstone National Park – and eastbound California. They besides recovered ash from eruptions lone 32,000 years agone – which is not truthful agelong agone successful the geological clip scale.

Jake Lowenstern, a probe geologist with the US Geological Survey who is not progressive with the study, told CNN that studying volcanic eruptions of the past tin assistance overgarment a representation of aboriginal risk.

The latest find successful Lake Mead whitethorn beryllium 1 of the “better” collections of volcanic ash from that play of time, Lowenstern said, and it volition “be important successful allowing america to reconstruct the geologic past of the region, and to recognize the frequence of ample volcanic eruptions and their interaction connected the Southwest.”

Ash from adjacent moderately explosive volcanic eruptions tin question hundreds of miles, blanketing areas arsenic acold distant arsenic respective meters with dense material. Recent eruptions person showed a mates of millimeters of damp ash tin disrupt energy transmission. And erstwhile inhaled, the tiny but crisp grains successful the ash airs a significant wellness risk.

“These ashfall events tin disrupt proscription and proviso networks, adjacent airports, and perchance beryllium a wellness hazard,” Smith said. “It’s important for section governments to make plans to woody with this benignant of event, similar they person for earthquakes and flooding.”

Smith said their latest investigation could assistance nine hole for aboriginal volcanic events, adjacent if from acold distant volcanoes – arsenic good arsenic “present and aboriginal clime change.”

“Studying the past is the cardinal to knowing the future,” Smith said. “By knowing past volcanic events, we tin amended recognize however a aboriginal lawsuit whitethorn impact a ample metropolitan area. We tin besides make plans to woody with a volcanic eruption erstwhile 1 occurs successful the future.”