The Avalanche Review, Vol. 5, No. 3, January 1987
Copyright All Rights Reserved; AAAP

Anatomy of an Avalanche
by Peter Lev

It is 1:00 p.m., July 23, 1974, in the Pamir Mountains, U.S.S.R.. I am distressed. A rapidly deteriorating avalanche condition has been developing on the steep slope above our 17,350 ft Crevasse Camp.

Crevasse Camp is located high in the accumulation area of the Krylenko Glacier. The camp is two-thirds of the way up a glacial slope which is north-facing, 6,000 ft high, and of nearly uniform steepness. No respite from this steepness is to be found, save for one large suspicious crevasse. A six man contingent of the of the American Pamir Expedition is camped in that crevasse. Above is the Krylenko Pass, 20,206 ft, a gap high on the long northeast shoulder of Pik Lenin. We must climb to Krylenko Pass and cross it, for we have aspirations of first ascents beyond the Pass.

On the morning of July 22, our group has ascended the steep slope above Crevasse Camp and reached the Pass. It was heavy going through knee-deep snow. How unusual, I thought, for my feet were becoming so cold, so early in the game. It was not that the air temperature was so cold, it was that the snow was unusually cold. Inspecting this snow closely, I found the grain size to be small and the grains or crystals to be very loose. These loose grains or crystals gave the upper two feet of the snowpack a very low density, the immediate practical result being that it was difficult to set a good step. As to avalanche potential, I didn't take these conditions to be a sign of instability.

We spent the day south of the Pass, on the Greater Saukdara Glacier, observing the East Face of Pik Lenin. It was a warm day with strong incoming radiation energy; the snow surface became wet and we suffered in the hot, stifling air on the glacier. At about 6:00 p.m., we began our descent from the Pass, heading back home to Crevasse Camp. Fred and I immediately realized that the condition of the slope above Crevasse Camp had changed radically since morning. A slab had developed. We were no longer wading through deep snow as we had during the morning ascent. We were now on a fairly stiff surface, sinking in only about six inches. The surface had a slight ice glaze and was damp two inches down. I was alarmed, so I dug a quick snow pit in order to see what had happened to the cold loose snow I remembered so well from the morning.

The slab was two feet thick and consisted of fine grain, old snow of medium density or hardness. I was able to reach to the underside of the slab and move my palms back and forth as though feeling the underside of a table! A slight icy crust firmed up the underside of the slab. The snow underneath this crust had undergone temperature gradient metamorphism and was the beginning stage of depth hoar (unstable, sugar-like snow) with moderate cohesion. The depth hoar was six inches deep and rested on an icy layer. To verify these findings we dug five snow pits. Each pit revealed the same situation.

There was no doubt that a potential avalanche condition had developed. And, by all known standards, it developed impossibly fast. We had, however, descended on the slab, indicating clearly that the slab had not yet reached a critical state. It appeared to me that the ameliorating factor was the absence of any increased weight in the form of new precipitation. The weather had been good; we hoped that it would continue to be so. We thought we were still ahead of the problem. I wanted to observe the situation by digging more snow pits on the following day. Fred wanted to go down. The others were divided. Descent and evacuation from Crevasse Camp was considered with reluctance. Probably without being fully aware of it, some of us may have thought: How can we turn back, after coming all of this way-to Russia, especially with the English climbers already over the Pass, at the base of the East Face of Lenin.

That evening, the altimeter began to rise; that is, the atmospheric pressure began to fall. We shouldn't have been surprised because we all saw the mare's tails streaming up from the southwest when we were on the south side of the Pass earlier in the day. At about 2:00 a.m., Bruce woke me up and said it was snowing. I stuck my hand out the tent door and wiggled my finger around. One inch of new snow, very light density, "Six inches of new snow would send us down to a lower and safer camp, " I said. Bruce said, "Are you sure?" Back to sleep... ZZZZZZZZZZ.

Early morning, July 23. Two inches of new snow, very light density. It was clear, but the barometer was still low. Blowing snow from a good 25 m.p.h. northeast wind. Could the wind be transporting enough new snow to bring the slab to a critical state? Then the wind abated and it became warm as in previous days. Are we being lulled into ignoring what is really happening around us?

By mid-morning, another American contingent arrived at Crevasse Camp. This was the five-person crew headed for the mountain Pik 6852, another hoped-for first ascent beyond Krylenko. We told them of the avalanche situation. They solemnly accepted this unwelcome news and set to moving camp, nevertheless. A Japanese party arrived with the intention of climbing to the Pass. We advised them to turn back because of the avalanche danger and they wisely did so. Finally, a minor crisis prompted action out of the East Face Pik Lenin crew. One of our stoves broke. Bruce, Allen, Fred, and John headed down to Base Camp to get the stove fixed, and to bring up more supplies. Jeff and I would stay, work with Jock's Pik 6852 group, and continue to assess the avalanche danger.

Now clouds are floating around and it is uncomfortably warm. Our boys left about half an hour ago on the stove repairing mission. Vague worry. I am watching my altimeter-barometer and the pressure is dropping rapidly. More clouds. I pace around. Mike, Jock, and Jeff are debating whether to move one of the tents so as to place it in a safer position should an avalanche occur. Mike wants to move it into the partly filled-in crevasse rather than leave it on the crevasse lip where the other tent is located. That would entail some considerable digging and leveling. We have to consider that kind of action carefully. A tent for Jeff and myself was already erected on the lip of the crevasse. It seemed it was going to stay right there.

Jock's crew tent is halfway erected. Mike is still protesting. By now, all of us are standing on the lip of the crevasse: Jeff, Jock, Jed, Molly, Chris and I. The clouds suddenly envelop us, and it gets noticeably warmer, then begins to snow. I am standing and staring at my altimeter; it rises 50 ft indicating a sudden drop in air pressure. More intense worry. The boys down below.. ? Jeff is saying in response to Mike, "Well, I am a fatalist..." Suddenly the crevasse shifts; shifts a whole lot: In fact, the whole mountain side seemed to vibrate! We silently look at each other. Impending.. .what? It is almost 1:30 p.m.

I really don't remember if it was the sound of the avalanche that warned us, but it must have been, because the upper overhanging lip of the big crevasse some 40 ft. overhead blocked our vision of the awful slope directly above. Most of us had never heard an avalanche so close before, and I certainly hadn't heard one from this position. But we all sensed instantly that the avalanche was coming. We had maybe 15 seconds from the time of the crevasse shift; we reacted in the last few seconds. I was eight feet from the crevasse-Iran and jumped in. Jeff was near me, doing the same. The drop into the crevasse was about 15 ft into the soft snow, and as I landed, I looked up to the high upper lip and saw, distinctly, a solid wall of snow shooting out, going incredibly fast, blocking out the sky in the darkness and roar.

Cold snow came in on me, burying me in the hole as I tried desperately to claw my way back out with bare hands, utterly without success. It went seemingly on and on, perhaps a full minute then stopped.

Spindrift from the avalanche is settling now, and it is snowing as well. I am buried to my knees. Jeff's calling from a few feet away asking if I'm still there. Yes. Jeff is buried up to his waist; I dig frantically. Jeff and I don't know yet . . . we may be the only ones left alive. What despair.

They are all there! Jock and Mike and Jed and Molly and Chris. Jock didn't get buried; he's dusting himself off with a characteristic air of "what is this nonsense here?" Jed was eating a dried apricot at the time; claims to have chewed it thoroughly while the avalanche passed by. Chris is shaken; so am I. He asks, "Is this bad?" "Yes, " I say, and think... our friends down below. The avalanche was so huge, at least 200 yards wide where we are, as far as we can make out... just doesn't seem feasible that they could have been far enough down and out of the way. We yell into the driving snow. No answer.

There was no sign of Jeff's and my tent. Jock's crew's tents had been completely flattened, damaged but recoverable. Guess that settled that argument. Jeff and I lost our packs and all of our gear, sleeping bags, parkas, most everything. The others lost equipment too, but not so much.

Driving snow and cold now. Avalanches roar in the mist. There is no good reason to stay here; it is becoming only more dangerous by the moment. Without crampons, some without axes and others using shovels as a substitute, each in turn fades with weariness and misery as we make our way down. For a long time our survival is in question.

Oh, the debris, acres and acres of debris: large heavy, damp lookIng boulder-shaped heaps of snow They could never have survived this. There is no way.

We reach the base of the face where we had left a cache on the ascent. Jed, on the lookout, insists that the cache is gone, but his words fall on deaf ears. Jed says that they, John, Allen, and Bruce, must have picked it up on their way down. No reaction.

Krylenko moraine camp. THERE THEY ARE! Relief upon relief. Yes, the avalanche hit them. But they were almost to the bottom of the big slope, in a low angle area, on the edge of the final run-out of the avalanche.

How could the boys have descended 3,000 ft. so quickly? The snow had been so deep and soft. They slid. They put on their nylon wind suits and slid. Fortunately so. Then the roar and wall of snow came out of the mist, but when it reached them, its force was dissipated. The avalanche scooped up the climbers and carried them 200 ft. Allen was buried up to his neck, the crushing weight of the snow bruising some of his ribs. The others came to rest on top of the debris.

It was so close, so very close. Just within inches, nearly 11 of us came that close to being killed. I flashed back to the scene at Crevasse Camp just seconds after dust had settled, when I was thinking real hard, just like a little kid, "Oh please, if we are all safe, I promise to do this, and this and this... "

The next day, bedraggled and very glad to be alive, we arrived back at Base Camp. We were told that at approximately 1:30 p.m., on the previous day, a tremendous earthquake occurred. The epicenter of this earthquake was about 100 miles south of Pik Lenin and Krylenko Pass. Some expedition members familiar with earthquake strength along the west coast of North America said the strength of this earthquake was five to five and a half on the Richter Scale. The violent shift of the glacier that we felt was the earthquake, although we didn't realize that at the time.

The Krylenko avalanche appeared to be the release of a damp slab on a temperature gradient layer, set in motion by the exceptionally heavy trigger of an earthquake.

The Avalanche Review, Vol. 5, No. 3, January 1987
Copyright All Rights Reserved; AAAP