Mount St. Helens' Steamy Crater Becomes a Lab for Scientists
Seen in profile from the snow-covered south and southwest slopes, Mount St. Helens is a serene, cloud-topped beauty rising 8,364 feet high in the Cascade Range, with Mount Rainier at its back and Mount Hood just to the south in Oregon. But as the chopper approaches the south rim, the image shifts dramatically to that of a blasted inferno, a smoldering crater some 2,000 feet deep, with boulders as large as houses strewn across its immense floor. In the middle of this pit rises a dome 2,080 feet long and 680 feet high—higher than any building in Portland, Oreg. Steam seeps into the air as if the hot rocks are breathing.
Flying into the crater is a very different matter from flying around it, and on the morning after our first fly-by, as we prepared to lift off following two crews of scientists from the observatory, there was a serious tone to the conversation. Our helicopter pilot, Dwight E. Reber, was intimately acquainted with the dangers of such flights, having made 250 of them in the last two years. Around the summit of the volcano the weather can change with treacherous speed, leaving an unwary pilot groping through dense cloud. The wind can veer capriciously, overpowering the helicopter and sending it spinning into a crash. In addition, the crater floor is highly unstable, composed of solid rock, drifts of soft ash, loose rock from the eruptions, and fragile snow bridges concealing crevasses up to 30 feet deep.
Reber put down the helicopter 300 yards from two figures wearing hooded parkas against the 25° cold and the whirling, ash-laden wind. Dr. Don Swanson, 43, the USGS laboratory's senior research scientist, who is also known as "king of the crater" for his exploits, had earlier scaled the side of the steaming dome to place orange "targets." Now Swanson and Bill Chadwick, a geological field assistant, were training survey instruments on the targets to measure movement, a method for determining expansion of the dome and predicting eruptions.
After last-minute instructions from the pilot, we hopped out onto the crater surface. Although we were in shade, the snow underfoot was mushy. We ran to a rock-strewn area 50 yards away, then turned and gave Reber a thumbs-up signal. He lifted off. Being in the crater without a helicopter brought home the thought that if Mother Nature wanted to eat us for breakfast, we really wouldn't have much to say in the matter. The land there is alive. Warm steam vents from cracks. Large rocks are hot to the touch. Hearing a noise, I turned to see a boulder five feet across tumbling down the dome's slopes.
Making our way with great care toward Swanson and Chadwick, we finally reached the firm footing of a rock field. Swanson and Chadwick had their backs to us and were completely absorbed in their work. Swanson, peering through a surveyor's theodolite, said, "2780909," and Chadwick, jotting down the figure, muttered, "Check." Then he observed, "That's not changed much."
After 10 minutes the two scientists shouldered the theodolite and moved on to another site in a sunny area of the crater. This time they trained a tripod-mounted device called an EDM (electronic distance meter) on the dome, measuring distance and angle to the targets. The instrument, which bounces infrared laser beams off the dome, sets off an occasional electronic beeping that sounds a great deal like Pac-Man.
Seemingly in a moment, the weather changed for the worse. We called in our chopper, intending to fly to another part of the crater. But once we were airborne, Reber advised us that heavy clouds and snow were coming in fast and that the USGS crews were ordered to get out. "I think we got you out just in time," he said.
Two days later we made a second descent into the crater. Geologist Kathy Cashman, 27, and Dr. Dan Dzurisin, 30, a soft-spoken volcano geo-physicist, were anxious to complete a series of measurements on the dome. But when our helicopter approached the crater this time, we noticed a startling change: The volcano was rumbling again, and a thick plume of ash and steam was belching up to 12,500 feet from a new fissure in the dome. Despite that, the scientists resolved to press ahead with their mission. They asked the pilot to descend through the veil of steam to a landing on the crater's west side. But 35 minutes later storm clouds darkened the sky, and a hailstorm forced an immediate evacuation. Pilot Reber had us aboard and was weaving through the scudding clouds when suddenly he spotted the helicopter that had come for the rest of the team. It was directly ahead, much too close, and only luck saved us all from a midair collision. The narrow escape left us shaken, and left us also with the thought that the volcano, with the merest fraction of its power, was warning us not to get too close, as so many had two years ago.