Pacing is always a concern for storytellers. You don’t want to go too quickly, lest you skip something important. You don’t want to get bogged down in the details, lest your readers yawn and wander off somewhere.
There is an extra concern when you’re talking about real-world events and cannot control the order in which they happened or the spacing of the interesting bits, as in telling stories about science. When your science writer in question is talking about events that happen at–literally–a geologic pace, things get even harder.
Dana Hunter has just finished a series on her Scientific American blog, called “Prelude to a Catastrophe”, that proves she’s up to the task of meeting all these challenges. It helps that she loves her topic, and it helps that we all know that there is an explosion coming. Still, the talent is all Dana’s.
The topic of her series? The eruption of Mount St. Helens in 1980. The story, however, starts in 1835. Dana makes the whole journey worthwhile.
Her former perfection was a sign of the cataclysm to come. When we see a volcano so exquisitely formed, her flanks so full, her form ungouged by the glaciers draped over her, we know she’s young and full of zest. She’s been active recently; she’s likely to awaken again at any moment.
And we knew.
But it’s one volcano in particular that’s caught your eye (or eyestalk): just to the west of Mt. Adams, the most symmetrical of the lot. It’s not the tallest, but it’s the youngest. The others are hundreds of thousands, all the way up to a million, years old. Mount St. Helens is a barely-adolescent 40,000. And it’s been extremely active.
This is the trouble with beginnings: the beginning is often subtle, and unrecognizable at the time. It’s only in retrospect that we can go back, look at sequences of events until we find a place to stab a finger down and say, “Here. Here is where it began. This is the time, the place, the event.” Even then, it’s usually only a beginning. There are many places to put the finger, many events to choose.
It began with earthquakes.
It must have been eerie for the observer in the Army National Guard plane who first saw the gaping hole in her formerly-pristine summit. A dark gray streak of ash stained the snow, following the winds to the southeast. The deep snow had cracked. She was awake. And it wouldn’t be long before she let folks know she was feeling feisty.
On March 27th, as the first phreatic eruptions fractured the summit and sent pulverized rock billowing to 7,000 feet, they moved quickly to mitigate the risks. Hundreds of people living within a 15 mile radius of Mount St. Helens found themselves bundled out to safety. Pacific Power and Light, working off hazards assessments, lowered their three reservoirs on the Lewis River to accommodate expected mudflows. And geologists flocked to the mountain for the opportunity of a lifetime. It’s not often a volcano so close to major population centers gets frisky.
The volcano steamed quietly under stormy Pacific Northwest skies. Some residents thought the show might be over, but geologists knew better. The song wasn’t done: the prima donna was taking a last deep breath. The only question was what sort of finale to expect.
One thing was certain. That bulge they had noticed in late March was going to come down. Its failure would be spectacular. That was beyond question. It was growing too fast, over-steepening itself too much, to stay put.
People depended on the scientists getting it right. They needed information: what was she up to? What was she likely to do next? What were the current and future hazards? Could they give a warning before the big bang came?
Remote monitoring of an active volcano can only tell you so much. Seismometers, tiltmeters, and other tools to assess from a distance can give some indication of what the volcano’s up to, but only so much. So as soon as St. Helens quieted down enough to be relatively safe, geologists took some calculated risks, not knowing for certain what the odds were. They collected samples of the gasses in the steam vents near the summit, looking for the kinds of gasses that could tell them more about magma.
Explosions ceased on May 15th, but the bulge continued its outward journey unabated, and steam hissed from its upper reaches. The summit radiated so much heat that the thermal energy equaled around 3 megawatts – if it could have been captured and used, it would have powered about 1,800 homes. Geologists found pits that appeared bottomless in the hottest areas. Two clusters of thermal infrared anomalies marked areas of weakness in the bulge. In two days, the bulge would come apart at those seams.