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Mount St. Helens is fast growing its new top

By MIKE LEWIS

The Seattle Post Intelligencer

USA - While on most late fall days the clouds obscure new growth, the meters 
on the mountain don't lie: Mount St. Helens continues to build a new 
mountaintop at a rapid rate. According to recent reports from the U.S. 
Geological Survey, the lava dome had grown to nearly 800 feet high and covers 
70 acres in the volcano's mile-wide crater. Geologists say the subsurface 
magma, the cause of the recent steady stream of earthquakes and steam that 
began in late September, is pushing the dome skyward with no indication of 
letting up.

At the current pace, the mountain could have a new top in less than two 
decades. But geologists have no idea how long the activity will last. 

Recent thermal imaging shows that the new lobes forming on the dome are 
rising at a rate of 30 feet a day. The highest point in the new dome is 7,400 
feet, according to recent data from instruments placed in the crater. At its 
highest point, the mountain is 8,364 feet. Before the 1980 eruption that 
killed 57 people, it stood at 9,677 feet.

During the past two weeks, seismic activity has increased slightly. While 
still not matching the temblors that shook the observation centers two months 
ago, the seismometers have detected crater floor earthquakes at a magnitude 
of 2.8. This is a marked increase from low-level activity in mid-October that 
diminished seismic readings and subsequent public interest.

Todd Cullings, assistant director of the Johnston Ridge and Coldwater Ridge 
visitor centers, said in a recent interview that activity in the centers has 
slowed considerably, but people still remain curious about the eruptions.

"When we have a nice day, they still come," he said. 

The increasing activity, geologists say, doesn't appear to indicate an 
increased likelihood of an explosive eruption. The lava reaching the surface 
is "gas poor," meaning that its capacity to explode is minimal. 

But according to a USGS alert issued early this week, while explosive 
eruptions are unlikely, they are not impossible. Also, the lack of gas does 
not mean activity has slowed.

"The steep west face of the dome is crumbling piecemeal but, as fractures 
grow, there is an increased chance of large slabs of hot rock toppling 
westward and forming ash clouds that drift out of the crater and hot 
avalanches, or pyroclastic flows," the alert noted. 

However, scientists said that as the dome pushes upward and crumbles aside, 
there isn't yet a threat of downstream mudflows resulting from the glowing 
rock coming into contact with the crater's glacier.


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P-I reporter Mike Lewis can be reached at 206-448-8140 or 
mikelewis AT seattlepi.com