USGS Photograph taken on April 10, 1980, by Tom Casadevall (also from the NE)
Both of the above from the USGS pre-May 18 photo archive. From the pre-eruption chronology at The Mount St Helens National Volcanic Monument web page,
April 10 - Weather cleared to permit aerial observations of continued explosions from a circular vent about 30 feet across in the western part of the crater. Harmonic tremor was detected for the first time in three days.Emphases in the above passage are mine. One of the aspects of pre-eruption events that is difficult to express in view of 20-20 hindsight was just how mundane it started to seem to non-geologists. I particularly recall the indignation of those involved in the timber industry, who felt they were unfairly- even illegally- being denied access to their livelihood. I felt a certain sympathy for their point of view, but at the same time, had a hard time comprehending how they could be so eager to rush toward a potential bomb. But as time went on, the constant complaining about the costs of maintaining the road blocks, and the forgone costs of shutting down the largest source of income in the area, became more and more compelling to those of us in the public with, shall we say, a certain degree of geological innocence. From here:
Steve Malone of the University of Washington reported that there had been 101 earthquakes with magnitudes larger than 4.0 since March 27.
The Cost of an Eruption - Explosions and earthquakes had settled into a monotonous pattern with no end in site. Mounting expenses began to affect the level of monitoring and maintenance of roadblocks.
Since March 20 the USFS estimated expenditures at $157,000. Skamania and Cowlitz Counties had spent $17,000 and $10,000, respectively, for their part in maintaining the roadblocks leading to the mountain.
The National Guard estimated costs of $3,800 per day since April 5 for their part in staffing roadblocks. Washington State Patrol spent over $5,000 for their part of this effort.
In order to reduce costs, the USFS grounded both observer planes, but kept one on standby in the event of an eruption. They also closed the press center at the Shilo Inn, ending twice daily briefings. Days before the USGS had reduced the number of scientists monitoring the volcano from 30 to between 5 and 10.
On April 10, residents and workers were allowed to return home after signing a release, which stated they knew the risks and accepted responsibility for their own safety. That same day Mount St. Helens erupted sending steam and ash fifteen thousand, five hundred feet above sea level. By this time the bulge was three hundred and twenty feet high.While I'm drawing much of the meat of these posts from available online sources, and it is difficult for me to recall, 30 years later, exactly what was going through my head on what date, I firmly remember that late April and May, up to the eighteenth, were, frankly, dull. It seemed like the same thing, over and over and over. Comparison of old photos to recent ones showed the north-side bulge distracting from the mountain's former symmetry. And as days went on, it became even more lumpy than before. It seems odd, in retrospect, to claim that what was to become one of the most important US geological events of the 20th century was preceded by a growing sense of boredom and apathy. A sense that what were, in retrospect, trivial expenditures to keep people out of harms way became so onerous that public officials chose to quit making those expenditures. But that's what I remember; while I had avidly been locating and reading as much as I could find up to this point, the mountain was becoming more monotonous background noise than something of real interest.
I would probably not be spoiling the ending of this story by linking Ron Schott's gigapan of the volcano. This looks like it was taken from near Windy Ridge, above Spirit Lake, NE of the mountain.
This is part 7 in a multi-part series on the events leading up to the catastrophic eruption of Mt. St Helens on May 18th, 1980, 30 years ago this spring. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6.