One of the largest earthquakes in the intermountain west killed 28 people and transformed local landscape
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IDAHO FALLS – In conjunction with Pocatello’s announcement that it was participating in the 2023 Great ShakeOut Drill Thursday, a worldwide event that allows participants to practice how to protect themselves during an earthquake, we thought it would be fun to look back at one of the area’s most deadly earthquakes.
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On Aug. 17, 1959, a 7.5 magnitude earthquake hit Hebgen Lake along the Madison River about 13 miles northwest of West Yellowstone, Montana at 11:37 p.m. It was the second-largest recorded earthquake in the continental U.S. at the time, according to the University of Montana.
“We don’t believe that earthquakes can get much larger in this region,” Mike Stickney, Director of Earthquake Studies for Montana Tech, told CBS affiliate KBZK in Bozeman, Montana in 2019.
The quake took 28 lives and its impact on the landscape is still visible today.
It also created one of the largest landslides in North America. Many people remember it as “the night the mountain fell in Yellowstone.”
Survivors recall what happened
John Owen was vacationing with his family that night. He was 15 at the time and remembers being jolted awake in the cabin where they were staying.
“I was thrown off the couch onto the floor,” Owen says in the 2019 interview with KBZK.
The owner of the resort where Owen and his family were staying was concerned the Hebgen Dam would burst, and he told the Owens to evacuate.
“Before long, there was just a stream of cars coming in,” Owen said.
Originally, the Madison River flowed in a northwest direction from Hebgen Dam through a mountain canyon toward Ennis. A fault line extended along the underbelly of the canyon.
The initial quake lasted less than a minute, but it only took a few seconds for the ground to collapse along the fault line and leave a 20-foot wall of exposed earth in its wake.
“Shortly following the massive quake, an immense slab of (rock) detached from the canyon slope and slid swiftly into the valley, snapping trees and tossing thousand-pound boulders in a fierce disarray. As debris plummeted to the canyon floor, a new natural dam formed at the foot of the canyon several miles downstream from Hebgen Dam,” the University of Montana says.
KBZK says the rocks that fell were “the size of houses.” The Madison River flooded the canyon, burying trees and campgrounds, including the one where the Owens stayed. The area the river engulfed is now known as Earthquake Lake.
Communities along the river’s path, including Ennis, evacuated. Montana Highway 287 was destroyed, along with a popular fishing lodge on the north side of Hebgen Lake.
“The Hillgard Fishing Lodge … fell into a gaping fissure caused by the displacement and plummeted into the lake just moments after owner Grace Miller (whose house is pictured in the main image above this story) jumped from inside the building,” reports the University of Montana.
The quake’s aftershocks were reportedly bigger than magnitude 6.5. Stickney says the ground never stopped shaking the night of the quake.
A total of 250 people escaped to what is now known as Refuge Point, a mountain peak in the quake’s path.
Though the canyon was pummeled with water, somehow Hebgen Dam held firm. It remains in place to this day. But the quake’s destruction left behind what KBZK describes as a “wasteland” that was unrecognizable to locals.
“In the morning, it was like we were in a new world,” Joanne Gartland, a survivor of the disaster, recalls. “(It’s) like we’d been in one world in the campground and somebody picked us up and put us on a different planet.”
The longterm impact
Rescue helicopters were sent in the next day to rescue survivors trapped on Refuge Point. The state got to work clearing debris and repairing roads and bridges, including Hebgen Dam. The majority of roads in the area were reopened several days later.
Though the earthquake was 13 miles away from Yellowstone National Park, it had a longterm effect on some of the park’s thermal features.
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“Prior to the quake, Old Faithful’s average eruption interval was 65 minutes. Within two to three years following the earthquake, Old Faithful’s average eruption interval increased to 74 minutes,” the University of Montana reports. “Within a few days of the quake, Sapphire Pool, a previously quiet hot spring in Yellowstone’s Biscuit Basin, began erupting over 200 feet high.”
The Hebgen Lake earthquake apparently destroyed the basin’s biscuit-like formations. Steamboat, the world’s tallest geyser inside Yellowstone’s Norris Geyser Basin, erupted about three years later after being dormant for 50 years.
Today, the U.S. Forest Service operates an Earthquake Lake Visitor Center off Highway 287 directly across from where the landslide took place. It’s about 27 miles from West Yellowstone and is open from May through September.
Over the years, numerous people impacted by the quake have shared their stories. One account involves three children who narrowly escaped after their parents were killed. There’s another account of a mother and child who survived, while her husband and three other children died.
Though the quake is now more than 60 years in the past, it’s taken some of the survivors that long to get over the trauma of that day. Irene Bennett and her son, the only survivors from a family of six, had an emotional visit to a memorial site several years ago.
“We walked up to the memorial boulder and they pointed out where they were camped. It was very emotional, but it brought closure to her,” a visitor center employee told KBZK.
And for some, the quake has created new family connections. When Owen’s father passed away years after the quake, the owner of the resort where they were staying that night, who had been a widower for several years at that point, married Owen’s mom.
“The man who led his family to safety … became his stepfather,” KBZK says.