It was a bit late (or the scientists were premature) but the Redoubt Volcano has finally begun erupting.  (See my previous post for context.) You’ve probably heard the top news on this by now.  Here are tidbits that might have been lost in the headlines.

• As of noon today (Tues, 3/24), there had been six eruptions.  Tuesday has been calm, but the official alert level remains at “High.”
• Besides the ash plume, and steam plume, there have been lahar flows — mud and water.  Some have reached all the way to Cook Inlet, 21 miles away. (But no damage so far at the Cook Inlet oil terminal, although workers were evacuated.)
• Some of these watery lahars have been 20-25 feet deep.
• A glacier has melted (causing the flooding).
• 24 hours before the first eruption, seismologists at the Alaska Volcano Observatory raised the alert level around the volcano, after swarms of earth tremors in the area. (So, yes there was some warning immediately before the explosion.)

Here’s a photo of one of the eruptions, on Monday March 23rd, 2009.

Mt. Redoubt erupting on March 23rd (AVO)

We think of Mt. St. Helens as America’s star volcano.  But, outside the continental U.S. there’s a lot of action.  Not only Hawaii’s dramatic Mauna Loa and Kilauea, but along Alaska’s Cook Inlet there are several “restless” volcanos.

Lately, it’s Redoubt Volcano, about 100 miles from Anchorage. It’s a striking peak, at 10,197 feet (just a little shorter than Mt. Baker in the Washington Cascades).  The U.S. Geological Survey says it expects “an eruption to begin within the next few days or weeks.”  Well, they started saying that more than a week ago.  So, hold onto your hats.

Areas of current activity on Redoubt Volcano, Alaska

Last time, in 1989 and 1990, it erupted more than 20 times over a period of several months.  It shot a huge ash plume into the air that almost caused a commercial jetliner to crash.  And melting glaciers turned a nearby river into roaring torrent — which nearly wiped out an oil terminal.  No oil leaked, but buried pipelines were scoured to the surface and thousands of gallons of crude were hastily transferred away.

What will happen this time?  The USGS says the most likely scenario is something similar to 1990.  But, volcano prediction is not the most precise of sciences.  (And for those wondering if there’s any seismic connection between Redoubt and Mt. St. Helens, the answer is no.)