West Yellowstone Area, MT - ID Earthquake Destruction, Aug 1959

Map Of Earthquake Center Hebgen Lake Overview Of Main Slide Hebgen Lake Damage Quake Damage


West Yellowstone (UPI) -- A series of mighty earthquakes smashed into southern Montana near Yellowstone Park Monday night and early today and a reported 16 persons were killed.
Montana Highway Patrolman ROBERT SPEARS said there could be 25 dead in the main slide and the toll "could go even higher."
The quakes brought an 8,000-foot mountain tumbling down, threatened to shatter a dam on the Madison River and endangered upwards of 150 campers in the river valley.
Helicopters from the western states, some carrying para-medics, were sent to the scene. The park is located mostly in Wyoming and also extends in Montana and Idaho.
'Copter pilots were expected to try to life to safety the campers marooned downstream below the Hebgen Dam and trapped by the 200 to 300-foot slide that closed off the only avenue of safety from the box canyon.
Reports On Fatalities.
Four of the reported dead were members of the PURLEY BENNETT family of Couer d'Alene, Idaho, buried when the quake split the mountain and triggered the main slide seven miles downstream.
Another couple nearby also were killed.
The Montana Civil Defense headquarters said it had been informed by Idaho State Police that eight dead had been found in Reynolds Pass on the south fork of the Madison River in Eastern Idaho.
Two more unidentified persons were killed in a rock slide at Cliff Lake, 12 miles west of Hebgen Lake.
The first quake hit at 11:39 p.m. p.d.t. Monday with a magnitude of 7.8 on the Richter scale. The San Francisco earthquake of 1906 measured 8.25.
The temblor was felt throughout the northwest but hit hardest near the juncture of Montana, Idaho and Wyoming in the Rocky Mountains.
Jolting afterwards followed at 12:59 a.m., 1:44 a.m., 3:08 a.m., and 8:28 a.m.
Crack Appears In Dam.
Three hours after the first schock a 17-foot crack appeared in the Hebgen Dam in Gallatin County. The Hebgen impounds the headwaters of Madison River which flows north into the Missouri River.
Hebgen Dam is only a few miles from the west entrance to Yellowstone Park where damage was reported light. However, rangers barred tourists from Old Faithful Geyser.
United Press International reporter PAUL QUINN said after a flight over the dam that "the entire side of a mountain was torn away, there were trees and rocks all over the top of the slide piled 200 to 300 feet above Highway 1.
Between the dam and the slide downriver sections of the highway were torn up.
"Cars were scattered all along the way with people standing outside," QUINN said. "Women and children were waving handkerchiefs and bandanas. SOS signals made with white clothing showed up clearly."
About 30 cars were located next to the downriver side of the dam.
Slide Blocks Tourists.
The series of quakes, first death-dealing temblors to strike this area since 1935, split open foothills as though they were eggshells. The north shore of the lake behind the dam was cropped off 6 to 15 feet, submerging the highway there. The south shore heaved up 6 to 15 feet as though the whole lake were tipped in a giant saucer.
Several homes floated crazily in the lake.
Telephones and electric power were knocked out in West Yellowstone. Chimneys fell, gasoline pumps tipped over and buildings were shifted from their foundations.
QUINN said the giant slide looked from the air "as if it had been shoved off a mountain top by a huge hand. It blocked the highway and trapped the tourists between it and the dam seven miles away."
Only a mother and son surrived in the PURLEY BENNETT family. The dead were BENNETT; daughters, CAROL, 17, and SUSAN, 5, and son, TOM, 11. "Suddenly there was a huge roar," PHIL BENNETT, 16, told UPI.
"I looked up and saw the mountain cascading down on us."
Highway Closed Down.
Rescue teams who reported eight dead in the Reynolds Pass area in eastern Idaho said they were leaving the area after recovering six bodies. They said there was nothing more they could do.
Idaho State Police blocked off Highway 191 leading to West Yellowstone. Cracks and sinking were reported in the highway.
Hebgen Dam was built in 1915. The mountain-ringed lake it backs up is 20 miles long and one fourth of a mile to six miles wide. It has a capacity of 325,000 acre-feet of water. Elevation of the lake is 6,500 feet.
Down stream from the slides, residents of Madison Valley -- under order of Sheriff LLOYD BROOK of Virginia City, Mont. -- fled from their lowland homes to higher ground.
When ROBERT E. CRENNEN of UPI arrived in Ennis shortly before daybreak, first newsman to reach the town about 50 miles below the dam, he said "99 per cent" of the town's 600 residents already were gone.
Have Time To Escape.
Although it trapped travelers between it and the dam, the fallen mountain was expected to give residents of the valley an extra 1 1/2 hours to escape from flood danger should the dam give way because the slide formed a temporary natural dam across the river.
QUINN said that from the air it was not possible to determine whether the dam had been damaged by the shocks, which by 6 a.m. were hitting West Yellowstone every 10 minutes. These aftershocks, however, were far smaller in intensity that the first one which registered a magnitude of 7.8 on the Richter scale.
An unidentified Montana Power Co. official at Butte, however, told QUINN that the quake opened a 17-foot-long crack in the dam.
QUINN said the "dam is brim full," however. The road upstream from the dam was covered by water when he flew over it, he said.

By Robert E. Crennen
United Press International
Ennis (UPI) -- This little ranching and tourist town is evacuated. Its population of 600 -- swelled by summer tourists -- has left by all conceivable modes of transportation in fear Hebgen Dam -- some 50 miles to the south -- will break and send a wall of water on the town.
I arrived here shortly before 5:30 a.m., the first newsman to reach the town. At that time it was 99 per cent evacuated. A little later, only highway patrol men and sheriff's deputies remained.
Merchants were taking as many valuables with them as possible -- loading them into everything imaginable, from two-ton trucks to Thunderbirds. Some men were leading teams of horses out of town.
Deputy Sheriff LARRY CRANDALL said the evacuation actually started about 2 a.m. when it was "suggested" to people that they might be in danger.
Later, sheriff's officers and patrolmen rang their sirens. The town siren was sounded. People ran from door to door saying "get out of town, the water's coming."
Telephone operators alerted everyone possible after Sheriff LLOYD BROOK ordered the entire Madison Valley evacuated.
MARVIN BROOK, 30, of Ennis, a volunteer assisting with the evacuation, said "there was a little panic at first because we caught the people unaware. However, after the first 45 minutes or so, the townspeople began to take it in stride and moved out of town in an orderly fashion."
Montana Power Co. officials estimated it would take 10 hours for the water to reach Ennis and another 10 for it to reach Three Forks if the dam broke wide open.
Things are quiet in Ennis now.
"We're just waiting for the water," CRANDALL said.

West Yellowstone, Mont. (UPI) -- Reported death toll from the Montana earthquakes:
1 -- PURLEY BENNETT, Coeur d'Alene, Idaho, killed in mountain slide seven miles down Madison River from Hebgen dam.
2 -- CAROL BENNETT, 17, daughter.
3 -- SUSAN BENNETT, 5, daughter.
4 -- TOM BENNETT, 11, son.
5 and 6 -- Two unidentified persons in BENNETT tent.
7 and 8 -- MR. and MRS. E. H. STRYKER, San Mateo, Calif.
9 through 16 -- Unidentified dead in Reynolds Pass on South Fork of Madison River in eastern Idaho. Six bodies recovered.

The Daily Inter Lake Kalispell Montana 1959-08-18