Earthquakes!

By editor

Near Cameron, Madison County, Montana, August 17, 1959

The earth beneath the Madison Valley is not finished. It has never been finished. The mountains that stand above the valley floor are still rising, still being thrust upward by forces that began working long before the first human eye looked upon them, and the valley floor itself is a graben, a block of crust that has dropped between two parallel faults while the ranges on either side climbed. This is not a metaphor. It is geology, the plain and patient record of what the earth has been doing here for the last several million years, and it is the reason that on the night of August 17, 1959, at eleven thirty-seven in the evening, the ground beneath the Madison Canyon moved in a way that no living person had ever felt before and that many of the people in the canyon that night did not survive to describe.

The earthquake that struck the Madison Valley that night measured 7.3 on the Richter scale. It was felt across more than six hundred thousand square miles, from Banff in Canada to Provo in Utah, from the western edge of North Dakota to the coast of Washington. In Yellowstone Park, eighteen thousand people who were sleeping in cabins and hotels and campgrounds were thrown from their beds. In West Yellowstone, the ground opened in crevices wide enough to swallow a man. At Hebgen Lake, seven miles of water began to slosh back and forth in a seiche wave that overtopped the dam and sent a wall of water twenty feet high down the narrow canyon below.

The fault that moved that night was the Hebgen Lake fault, a normal fault that runs along the north shore of the lake. When it slipped, parts of the Hebgen Lake basin subsided as much as twenty-two feet. The Red Canyon fault also ruptured. The two faults moved together in a matter of seconds, releasing energy that had been accumulating for centuries, and the result was a landscape that looked, in the morning light, as though someone had taken the valley and shaken it the way a man shakes a rug.

Geologist Irving Witkind of the United States Geological Survey was living in a trailer on a rise above the lake, surveying and mapping the area, when the first shock hit. He thought his trailer had broken loose and was rolling down the hill. He charged outside to stop it. When he saw the trees swaying in the absence of any wind, he understood what was happening. He jumped in his jeep and drove toward the lake. He saw the scarp that the earthquake had raised across the road just in time to stop. He got out of the jeep and stood on the shaking ground and looked at what the earth had done.

"It's mine! It's mine!" he shouted.

For a geologist, it was the equivalent of an Egyptologist stumbling into an unopened pharaoh's tomb. The earthquake had given him a living laboratory, a fault scarp fresh from the earth, a seiche wave still moving across the lake, a landscape in the act of becoming something different from what it had been the day before. His professional fortune was, as Edmund Christopherson wrote in 1960, "once in a thousand lifetimes."

The people in the Rock Creek Campground, a mile from the mouth of the canyon, had no such perspective.

Grover Mault was seventy-two years old, a retired decorator from Temple City, California, and he and his wife Lillian, sixty-eight, had parked their trailer at Rock Creek for a week before the earthquake. They were asleep when the first shock hit. Mrs. Mault thought it was a bear trying to get into the trailer. Then the trailer was tossed end over end. It landed, miraculously, on its wheels. Then something picked it up and threw it into the water.

Mault got his wife out of the trailer and onto the roof. He went back inside for clothing. When he came out, the water was at his chin. He climbed onto the roof, wrapped clothing around his wife's legs, and watched the water rise to cover the trailer beneath them. The trailer drifted toward a tree. He grabbed a branch. It broke. He grabbed another. It broke. He found a branch that held and wrapped one arm around the tree and held his wife with the other arm while the trailer was swept out from under them.

"It was horrible," he said afterward. "As I tried to pull the missus up the limbs kept breaking off. I tried to grab higher limbs and cling to the missus with my legs. The limbs still kept breaking off. Finally we found a limb that would hold."

They clung to that tree all night, in water up to their necks, while the mountains continued to slide and the aftershocks rolled through the canyon every few minutes. Mrs. Mault slipped under the water three or four times. The last time she was gasping for breath when her husband pulled her out.

"'Let me go and save yourself,' she begged. 'If you go, I'll go, too,' I told her."

At eight o'clock in the morning, nearly nine hours after the earthquake, rescuers came for them in a boat. The water had risen so fast that the rescuers had to move their truck three times before they could unload the boat. When they reached the Maults, the old couple could not move their legs. They had been frozen in place for so long that the men had to lift them into the boat.

The cause of the rising water was the mountain itself. At the moment the earthquake struck, half of a 7,600-foot peak on the south wall of the canyon had broken loose and come down. Eighty million tons of rock, forty-four million cubic yards of quartzite and dolomite, cascaded off the canyon wall and across the valley floor and up the opposite wall, moving like water, carrying house-sized boulders that struck sparks as they tumbled. The slide dammed the Madison River and created a new lake, which the Forest Service would later name Earthquake Lake. The water backed up into the campground. The water that trapped the Maults in their tree was the river, dammed by the mountain.

Twenty-eight people died in the Madison Canyon that night. The Bennett family of Coeur d'Alene, Idaho, had pulled their trailer off the road at the mouth of the canyon to rest for a few hours before continuing to Yellowstone. Purley Bennett, a forty-three-year-old truck driver, stepped outside when the noise woke him. His wife Irene was right behind him. As she stepped out, she felt a strong wind. The slide had compressed the air in the canyon as it fell, and the air was now rushing out at hurricane velocity. She saw her husband grab a small tree for support. The wind swept him off his feet. He hung on like a flag on a mast. Then he let go and was blown away. She never saw him again. A car rolled past, end over end, through the air. She was swept along with the trees and the rocks and the water.

"When I came to," she told reporters the next morning, "I was jammed against a tree with a log on my back. I don't know how I got out. I thought I was the only one of my family still alive."

Her husband and her sons were already dead.

The Intermountain Seismic Belt runs eight hundred miles from northwestern Montana through Yellowstone to southwestern Utah, and Montana averages five earthquakes a day along its length, most of them too small to feel. The 1959 earthquake was not too small to feel. It was the largest earthquake recorded in the Rocky Mountain region in the twentieth century, and it changed the landscape of the Madison Valley in ways that are still visible today. The new lake is still there. The slide is still there. The fault scarp that Witkind drove toward in his jeep is still there, a step in the earth several feet high where the ground dropped on one side of the fault and stayed put on the other.

The earth beneath the Madison Valley is not finished. It has never been finished. The forces that built the mountains are still working, still accumulating stress along the faults, still preparing the next adjustment. The geysers of Yellowstone, thirty miles to the east, are the surface expression of the same heat that drives the faulting, the same deep engine that shook the canyon in 1959. Montana averages five earthquakes a day. Most of them are too small to feel. The ones that are not too small to feel are the ones that remind the people who live here that the ground beneath their feet is not a finished product.

It is a work in progress.

See also

• Earthquakes! near Cameron, Madison County (Montana Department of Transportation, erected 2022)
• Earthquake Lake Visitor Center at Gallatin National Forest -- the Forest Service interpretive site at the 1959 slide
• Hebgen Lake -- the lake whose basin subsided up to 22 feet in the 1959 earthquake