Not doing my morning post(s) seems to make me very unhappy — positively explosive — so here I am, as if nothing is wrong (hoping the WordPress page will load by the time I’ve finished typing this in WordPad).
At 8:32 A.M. on May18, the bulging north face of Mount St. Helens finally reached the point of instability, and the result was a landslide. This was the trigger for everything that followed — a total release of energy roughly equivalent to the detonation of one Hiroshima-sized atomic bomb every second over the ensuing nine hours.
It so happened that two geologists, Keith and Dorothy Stiffel, were at that very moment watching the mountain from a light plane directly above the summit. Dorothy had a fear of flying, and this was her first flight in a small plane. She was just growing comfortable with the experience when all hell broke loose below the plane. The Stoffels later described what they saw:
As we were looking directly down on the summit crater, everything north of a line drawn east-west across the northern side of the summit crater began to move as one gigantic mass. The nature of the movement was eerie, like nothing we had ever seen before. The entire mass began to ripple and churn up, without moving laterally. Then the entire north side of the summit began sliding to the north along a deep-seated plane. We were amazed and excited with the realization that we were watching this landslide of unbelievable proportions slide down the north side of the mountain towards Spirit Lake. We took pictures of this slide sequence occurring but before we could snap off more than a few pictures, a huge explosion blasted out of the detachment plane. We neither felt nor heard a thing even though we were just east of the summit at the time.
They did not have time to watch events develop further because the blast could rapidly threatened to envelop their plane. Although the pilot, twenty-three-year-old Bruce Judson, turned the plane and flew away at top speed, the blast still gained on them. Judson was able to accelerate by putting the aircraft into a steep dive; by heading southward through a gap in the blast cloud, they just escaped — “by microseconds,” as the scientists put it.
The avalanche was one of the largest in recorded history: about three-quarters of a cubic mile of rock and ice rushed down the slope at a speed of up to 150 miles per hour.
Before I source the above, I want to say that I really wish writers would quit casually using “Hiroshima-sized atomic bomb” as if it were simply a unit of measurement.
The source for the above quote and what follows is an essay, Blasts from the Past: Mount St. Helens and Her Sleeping Sisters, by Kerry Sieh and Simon LeVay in the photography book, Mount St. Helens: Photographs by Frank Gohlke (2005); (on sale at Daedalus books, if you’re interested). The Sieh/LeVay piece is a really good outline of both the long and short term history of volcanoes.
How well did government respond?
The DES was notified of the eruption by Gerald Martin’s final message, as well as by messages from the Emergency Command Center in Vancouver during the next few minutes, but it took the agency nearly two hours to put out a statewide warning about the eruption. The reasons for the delay, and its consequences, were later analyzed in a study by Thomas Saarinene and James Sell. According to this study, the DES was a small, underfunded, ill-equipped agency of twenty-five employees run by a political appointee with no hazard-management experience. When the warning messages came in, the onsite staff insisted on waiting for “official” confirmation from the USGS and the Forest Service, but the phone lines soon became jammed and no such confirmation came through. Therefore they did not act on the radioed warnings, nor even on reports from the Seattle Weather Service that described flash floods and the trajectory of the eruption cloud. The eruption was on radio and television news an hour before the DES did anything; in fact, according to one DES official, the DES used the news reports as it major source of information. And when the DES eventually did try to activate the National Warning System, which was supposed to alert all the local emergency services automatically, the system did not work. The DES had to resort to sending teletype messages to the law enforcement agencies around the state. The National Warning System also failed to work after two subsequent eruptions (May 25 and June 12).
Some of the consequences of the delay were merely ludicrous: the police chief of one town that was being pelted with chunks of pumice called the county Department of Emergency Services, only to be firmly reassured that no eruption was in progress.
A miniature Katrina.
If you’re interested in volcanoes, there is a great movie, Supervolcano, about what would happen if/when Yellowstone next blows. (It will make Mount St. Helens look like a mosquito bite.)
-Julie
