Part 5

At the site of the slide, a relatively strong and nearly vertical layer of dolomite rock supported a huge bank, or mountain, of comparatively unstable schist and kept it from sliding into the valley in the same way that a retaining wall keeps a hillside terrace from slipping downhill. The tremendous shock waves of the earthquake fractured this dolomite buttress, and some 43 million cubic yards, or 80 million tons of rock, timber, and other mountainside debris cascaded off the slope, hurtled into the canyon, and surged up the opposite side, carrying huge trees and house-sized boulders as if they were weightless, hollow toys.

When this huge mass whomped down onto the river bed, it forced out the water and air trapped underneath at hurricane velocity. The huge slide spurted mud, air, and water with such force as to send two-ton cars sailing through the air, and to grind others to suitcase thickness against the rocks.

All this happened in seconds.

It would take eight seconds for the mass at the top of the mountain to fall to the valley floor 1,200 ft. below. At the time it reached this point, the mass would be travelling 174 miles per hour. The time it took to zoom half-a-mile across the valley, up the opposite canyon wall, then split and flow three-quarters-of-a-mile up and down the valley (the slide lies one-and-a-half-miles-long in the valley), was less than thirty seconds!

The fact that timber from the face of the mountain is spread in relatively uniform fashion over the entire surface of the slide is interpreted to mean that there was little tumbling action--that the slide moved as a single, if shattered, mass.

One important scientific controversy has emerged from the earthquake. It relates to the time relationship, or sequence between the initial shock, the tidal waves, or seiches, how fast the huge quantities of water which overtopped the dam moved down the valley, and whether these slugs of water had rushed through the canyon in time to reach the site of the slide before the mountain fell.

The stretch of the Madison running through the canyon is fresh, fast water, but normally it takes up to two hours for an object to run the sparkling, seven-mile, trout-rich stretch from Hebgen Dam to the mouth of the canyon. The big surges of water--the seiches overtopping the dam--would make it a lot faster.

There are two big, related questions.

Could the big surges of water reach the point of the slide soon enough?

And just how soon after the first shock did the mountain fall?

For the first couple of days after the quake, the theory persisted that the slide must have happened quite some time after the first shock--as late as 5:00 A. M., according to some theorists.

But, as the facts, and the testimony of folks trapped near the slide--the Osts, Fredericks, Smiths, and Mrs. Bennett--became available, it was apparent that the slide must have closely followed the initial shock. Even if you discount the disrupted time sense of people under stress--when a minute can seem like an hour, and vice versa--it's difficult to imagine that more than 20 minutes elapsed between the first shock and the slide.

According to one set of calculations, big waves could have swept from the dam to the slide site in 18 minutes or so.

Hebgen Lake Hebgen Fault Red Canyon Fault

Although the quake caused much settling of the earth packed against the downstream side of Hebgen Dam's concrete core, the relatively slight displacement of the sod cover is interpreted to mean that all three tidal waves passed over the dam before this earth subsided and separated from the core. Thus the water would have begun its race down the valley before the heavy earth-settling shocks hit the dam area.

Those who support the high-water-at-the-moment-of-the-slide theory point to the great volume of water damage way below the slide.

If the slide had come first, it would have dammed off the tidal waves, and prevented such damage. They feel there just wasn't enough water in the river bed's normal content to cause the water damage done both upstream and downstream by the slide. And they argue, the mud and dust in the composition of the slide would have taken up most of the water normally found in the reach of the river buried under the slide.

There's further evidence in the numerous fish found high and dry on the flat along the river bank several feet higher than the streambed. Most of them were small, catfish-like chubs. There were numerous trout, and one 18-inch carp. There is no place in the river below the pool at the toe of the dam where carp would likely be found.

Also, there was further confirmation in the fact that three of the especially made 11-inch squared timbers, eight and a half feet long, with notched ends and two U-bolts used as stop-logs in the Hebgen Dam spillway were found below the slide. Some shadow was cast on this as absolute confirmation by the Montana Power Co.'s explanation that stop-logs have been lost from time to time before the quake.

Those who, in spite of such evidence, oppose the theory that the high water reached the slide area first just don't feel that the water could have made it all the way down the canyon in so short a time. They feel that it would have taken at least 40 minutes for the big waves to traverse the seven miles. They have some support in L. D. Smith's testimony that in driving down from Beaver Creek to Rock Creek right after the shocks, he saw no such waves.

At any rate, this is one argument that geologists and hydrologists will be batting around for a long time.

NOW YOU CAN SEE

It's unusual when an event so spectacular as the Montana-Yellowstone Earthquake doesn't produce some exploitable possibilities, and this one did. The month after this August 17, 1959 series of quakes, the U. S. Forest Service, which is proprietor of the vast and tumultuous real estate on which the major portion of the immediate quake action happened, announced that is was underway with plans to set up a Geological Area to help visitors get to earthquake interest points and to understand the tremendous earth forces which operated here.

They held the inaugural of the Madison River Canyon Earthquake Area--the first of its kind anywhere--on August 17, 1960, the first anniversary of the quake. Relatives of the 28 quake victims sat on the gigantic slide as they unveiled the bronze memorial plaque mounted on the huge dolomite boulder which had floated across the valley atop the surging debris.

This awesome and fascinating earthquake area quickly became one of the region's top tourist attractions, with close to half-a-million visitors in attendance during each of the first two post-quake summers, in spite of miserable to nearly impassable access roads. This popularity is especially fitting because the quake that's on display here was essentially a "tourist earthquake". It happened in the scenic mountain area which draws a brisk vacation traffic from all over the U. S. and Canada, during the height of the tourist season. And those who went through the adventure, the thrills, the terror, the heroes and the helped, the survivors, and the casualties, could nearly all be classed as tourists.

Superb trout fishing has always been one of the area's most important features, and, understandably, there was much post-quake concern as to how this would be affected. While Hebgen Lake was drained to repair the quake-damaged Hebgen Dam, Montana's Fish and Game Department poisoned the trash fish and stocked the refilled lake with millions of rainbow trout running in size from fingerlings to 9-inchers. Today both Hebgen and Quake Lake--formed by the damming action of the slide at the mouth of Madison Canyon, afford top fishing, either from shore or from boat. Quake Lake has a made-to-order launching ramp at Cabin Creek, where the flooded-out road runs right into the lake.

In spite of the concern by fish biologists that silting from the slide would take the edge off fishing on the Madison below the slide area, it kept right on providing fishermen the top-notch action that had long earned its reputation as a blue-ribbon trout stream that compares with fishing anywhere in the world.

Today there are excellent roads to and through the Earthquake Area. Route 287, south from Ennis, leads directly to the huge slide at the mouth of Madison Canyon. Here the Forest Service has built a surfaced road up onto the slide. On top is the best vantage point to view the whole panorama of the mountain fall--where it dropped from, how in a matter of seconds 80-million tons of rock cut off the valley, the sparkling blue lake it created, and the open stretch of the Madison below the canyon. Besides, on the slide there are interpretive exhibits, and the huge monolith bearing the plaque to the quake dead, 21 of whom still lie somewhere beneath this mammoth pile of rock.

The relocated route runs eastward down the slide, along Quake Lake, and through Madison Canyon. Several Forest Service people staff the formally designated Earthquake Area during the summer season to help explain and interpret what happened here. Definite plans for the area include a formal visitor center, and at least one first-class campground in the slide-lake-canyon area.

Hebgen Dam, the dam that held, straddles the upper end of Madison Canyon. The road from here along Hebgen Lake to the Duck Creek Y has been much improved over its pre-quake status.

The Quake Area is just as easily approachable from West Yellowstone by taking 191 north 10 miles to the Duck Creek Y, and then driving west along Hebgen Lake. Near the Y, the big fault runs close to the road, through the Culligan ranch, etc.

The magnificent Raynolds Pass road, which runs south from its junction with the Madison Canyon road three miles west of the slide, has become an important new route to the earthquake area. The morning after the slide, highway crews were at work on this alternate route, which for two years substituted for the blocked, flooded, and destroyed road through the Madison Canyon and along the north shore of Hebgen Lake while the regular route between Ennis and West Yellowstone remained blocked. With its exciting mountain backdrop, this new, improved road provides an enjoyable alternative which should be included in any circle tour of quake features.

In the spring of 1959, as he tells it, Lemuel Garrison, Superintendent of Yellowstone National Park, looked at some bids for new housing in the Park which included extra steel as a protection against the possibility of earthquakes.

"Heck," he said, "We're not in an earthquake area."

Today, Yellowstone's famous earthquake has become an important addition to its already fabulous attractions. The Park took the quake in its stride. By June 1, 1960, in spite of road damage of $2,600,000, and building damage of $1,700,000 resulting from the quake, Yellowstone Park, its roads, and other facilities were ready for its normal summer rush.

In clearing a slide which blocked the road near Firehole Falls, south of Madison Junction, the road crew discovered one near casualty--a bear. The bruin had evidently sought shelter in a hollow below the road shoulder, and became trapped when the slide closed his exit. It was several days after the quake when the crew heard the bear's attempts to crawl out of his artificial cave. They lowered a tree trunk, still bearing branches, into the hole and retreated while the bear scrambled out.

Word of the quake plus the initial belief that the epicenters of seven of the eleven major shocks were located in the famous Firehole Basin caused widespread anxiety as to whether the tremendous forces loosed might have interfered with nature's intricate underground plumbing which keeps the geysers, hot pools, and mud pots spouting, burbling and burping.

Studies by a horde of seismologists, geologists and other earth scientists who swarmed into the Firehole Basin in the months after the quake show that during the night of August 17 the hot spring activity in this area changed more than during the 87 years since a park was created out of the mysterious, steaming country which had been known as "Coulter's Hell." The scientists termed these changes as "profound and far reaching." These changes in thermal features are, and will be, in years to come, tremendously interesting.

The majority of these changes came with, or just after, the initial quakes. The earthquake acted as a trigger to start eruption in hundreds of springs, nearly half of them erupting for the first time in their known histories. The whole place blew, then subsided.

There was considerable juggling of the intervals and playing times of some of the better-known geysers. Great Fountain, Riverside, Daisy, Castle, and Oblong shortened the length of their eruption intervals, but they play nearly twice as frequently as they did prior to the quake. Sapphire, a minor geyser, became a major geyser, but has subsided to a status somewhere in between. Clepsydra Geyser went frantically wild, and has erupted continuously since the quake.

Steady Geyser just up and quit. So did Grand Geyser. Giantess Geyser, located just across the river from Old Faithful, habitually shook the ground in the vicinity every time it erupted. Right after the quake it blasted off and kept blowing for a continuous 100 hours, instead of its usual 30-hour run. The Fountain Paint Pots became so active, and spread so, that they took over what used to be an asphalt-paved parking area.

In the midst of these changing patterns, Old Faithful goes on in much the same way, except for perhaps a slight increased interval between blasts. Studies of 14,317 eruptions were clocked, with an average interval of 63.8 minutes. The shortest interval was 33 minutes, in 1948-51, the longest is 93 minutes, measured in '55.

But none of these changes are static. Just when Grand Geyser, having been dormant for five months, was considered dead, it moved into a sporadic blasting phase.

These quake-caused fluctuations in thermal features, plus strong curiosity as to the earthquake's effects in the surrounding area, Sup't. Lon Garrison feels, will make Yellowstone's post-quake years bigger than ever.

QUAKE LAKE Smokejumpers SLIDE destroyed road 5 bodies found 19 presumed buried under slide helicopter took victims here Quake Exhibits Old Madison Valley Fault RAYNOLDS PASS Raynolds Pass Road (replacing Madison Canyon road knocked out by Quake) CLIFF LAKE 2 fatalities RED CANYON FAULT HEBGEN LAKE HEBGEN FAULT Road fell into Lake Improvised road Sandspout 4 Air Force Helicopters WEST YELLOWSTONE Injured transferred from helicopter for flight to hospital

MONTANA-YELLOWSTONE EARTHQUAKE

ABOUT THE AUTHOR

Ed Christopherson was a professional author and magazine writer whose articles about Montana, the Northwest, and other subjects appear in The Saturday Evening Post, Holiday, This Week Magazine, Mademoiselle, Reader's Digest, The New York Times, Congressional Record, etc.

Born in Ohio, he began his writing career in New York. His introduction to the Mountain Northwest came through a season as a Forest Service Smokejumper. After several years in New York, he picked exciting and scenic Western Montana as the center of his regional writing activities.

Christopherson went to West Yellowstone (they called it "Shookville") the day after the quake. He got first hand accounts from survivors there, and in Ennis, flew and walked over the slide and elsewhere in the quake area, and since has spent months researching and correlating what turned out to be "The Night The Mountain Fell."

Transcriber's Notes

--Retained publication information from the printed edition: this eBook is public-domain in the country of publication.

--Silently corrected a few typos.

--Transcribed some text within images.

--In the text versions only, text in italics is delimited by _underscores_.