Transcript for ARCHIVAL VIDEO: Mt. St. Helens Erupts in 1980
There is no simple way to describe what we are witnessing every actor Tim every superlative applies. From the sky within an hour after the explosive eruption this is what it looked like the column of ash and steam is solid and dance lightning bolts are visible from time to time. Striking the mountain top and lighting the center of the column. What a state university geologist Tom Benson was aboard this flight and described. What we saw using like this is ten times anything we've seen. At least give you talent there'd been any change to the top of the mountain yes a good deal of the top of the mountain has gone. What barbecue night on a shoestring glacier on the north side there's anyone all of shoestring glaciers are playing. I'm trying to figure out how far down toward goat Bucs have gone back. Let's put it this way I think the greater probably. At least tripled in size. Probably that's his morning. Is this the big explosion everybody's been waiting for there's just say first big explosion we've seen yeah. That's not to eliminate out the possibility of more. I don't really really don't know at this point. The state patrol early in the day within minutes after the flash flood announcement was made closed off interstate five and other highways into the aria and this is why. This wave of debris logs slash and mud from a Weyerhaeuser camp on the north side of the mountain was washed away. A solid mass of material at least a mile long plunging down the total river. Further up river observers estimated the height of the wave to be at least twelve feet. But by the time the floodwaters had reached as part of the river near council rock the river widened allowing the force of the flood to be defused. The logs piled up around the base of bridge columns is stacked up in bands in the river the level of the water without doubt rose. Bringing water to the back doors of some homes and cabins along the river bridges along the upper reaches on it or buried the bridges along the lower wages holding up. This may or may not be the big explosion that geologists have been predicting it is at least the biggest eruption since the initial eruption of the mountain last march 27. Airborne near mount saint helens Tim stores reporting channel two news.
This transcript has been automatically generated and may not be 100% accurate.