Laser scans reveal ‘hidden’ active faults in Yellowstone

A number of “hidden” geologic hazards have been discovered in the northern edge of Yellowstone National Park, including active faults that could pose seismic threats to area communities.

The flaws were revealed with what is known as light detection and ranging, or lidar, a type of remote sensing. which can pierce through dense foliage and detect hidden items on the ground in detail. The technology has found wide use in a variety of scientific fields, from archeology to geology, as a way to study landscapes that are normally dark or inaccessible to humans.

“Over the last 10 to 15 years, it’s been almost a lidar revolution,” said Yann Gavillot, a research geologist with the Montana Bureau of Mines and Geology.

Lidar works by using laser sensors mounted on airplanes or drones to bounce pulses of light off surfaces to detect features and map their contours.

Gavillot, who is also an associate professor at Montana Technological University, said lidar has improved what scientists can see with both aerial photography and people on the ground. Instead, laser scanning technology offers something akin to X-ray vision, allowing researchers to detect ground deformation and other telltale signs of hidden geological hazards.

“It’s really allowed us to look in much more detail at high resolution where these features are on the landscape,” he said. “And since that technology came along, it’s becoming a staple for geologists interested in geohazards.”

In 2000, LIDAR surveys were conducted in Park County, Montana, and the the resulting data set was made public last year.

In it, Gavillot and his colleagues discovered a vast network of faults traveling more than 33 miles on the northern outskirts of Yellowstone National Park between Tom Miner Creek Road and Livingston, Montana. Fault scarps are essentially breaks in the ground that are evidence of past earthquakes. Gavillot said the ruptures in this region were likely caused by tremors of around magnitude 6.5 or higher.

Lidar studies also revealed cracks in the ground that are believed to be related to a fault system that extends into the park, he added.

Yellowstone National Park is known for its supervolcano and active geysers, but lidar technology is helping scientists better understand the earthquake threat to surrounding communities like Paradise Valley in Montana.

The region is no stranger to damaging earthquakes: A magnitude 7.3 tremor that struck southwestern Montana in 1959 killed 28 people and caused a devastating landslide that displaced about 50 million cubic yards of rock, mud and Debris in Madison Canyon. according to the US Geological Survey..

The earthquake, which became known as the Hegben Lake event, also affected hydrothermal features in Yellowstone. After the earthquake struck, the Geological Survey reported that at least 289 springs in a portion of the Firehole River erupted as geysers, including many that had not erupted before in recorded history.

The 1959 earthquake and landslide offer a glimpse of what could happen if another major event were to hit Montana’s Paradise Valley, Gavillot said.

LIDAR data will help geologists further analyze the faults, allowing them to examine the bedrock and study how the ground has changed over time. By looking back in time, scientists can gain insight into future risks to the region.

“By looking at the fault, we can predict what size we expect from an earthquake and how much energy could be released,” Gavillot said.

He added that the technology opens avenues to investigate whether and how seismic events in Yellowstone may be related to geothermal and volcanic activity in the park. And beyond that, it is part of a broader symphony of tools used to understand the earth and its interrelated ecosystems.

“The power of lidar is that, yes, it can produce these beautiful images and we can find faults, but it’s also used by people who look at flooding, forestry and volcanology,” Gavillot said. “The more data that comes in, the more we find, so there’s a lot more work to do.”