USGS Geophysicist John Power Updates on Mt. Redoubt

Brian Campbell:  Another explosive eruption of Mt. Redoubt in Alaska is expected within days to weeks.  Earthquake activity has increased at the volcano since May 2.

We are joined on the phone with USGS Geophysicist John Power, who is based at the Alaska Volcano Observatory to discuss the situation.  Thanks for being with us today, John.

John Power:  Sure, it's good to be here.

Brian Campbell:    John, tell me about what has been happening at Mt. Redoubt since May 2.

John Power:  What we've seen beginning on May 2 is a very subtle increase in very shallow earthquake activity directly beneath the growing lava dome in the volcano's summit crater.  These volcanic earthquakes are very, very small, about magnitude, say, 0.1.  These earthquakes have a very characteristic signal.  They occur about 6 to 11, 12 times per minute.  They're very small.  The waveforms from the individual earthquakes are almost identical.

01:03

This is a very characteristic type of earthquake activity that we've noticed at Redoubt prior to earlier explosive eruptions that have occurred, most notably on April 4 of this year.  So, it is something that we have identified as a precursor to upcoming explosive eruptions which can be much more hazardous for people in South Central Alaska.

Brian Campbell:  How does the current activity of Mt. Redoubt compare to what we observed prior to its becoming active again in March?

John Power:  What we've seen at Redoubt since it became active again on March 22 is a whole series of explosive eruptions and many of them have been separated by the growth of the lava dome inside the summit crater.

The lava dome that's growing there now has become very, very large.  It's the largest lava dome that we've seen during this eruptive sequence, and preliminary estimates of it suggests that it's larger than any of the lava domes that grew at Mt. Redoubt during its earlier eruption in 1989, 1990.

02:10

What we're most concerned about at this particular point in time is the destabilization of that lava dome accompanied with these earthquakes that have been equated to the onset or renewed explosive activity that can produce very large ash plumes that have some very hazardous effects for either overflying aircraft as well as community surrounding the volcano.

Brian Campbell:  What does this mean for Anchorage and other areas of residence?

John Power:  Redoubt is very close to the most populous areas of Alaska.  Most of the people who live in Alaska are here in South Central.  When Redoubt does erupt, it puts out very large ash plumes.  These ash plumes are carried by the winds.  They result either in ash fall coming directly in communities such as Anchorage, Kenai, Homer, Palmer, Wasilla.

03:01

Once this happens, it's a very messy situation.  The ash is a well-known industrial abrasive.  It has damaging effects for cars.  People with respiratory problems are particularly at risk for some of the problems associated with ash fall.

Of course, no one suffers from ash fall or ash in the air as much as the operation of aircraft, which is something here in Alaska we're quite dependent upon.  You can think of the ash in the air, these large ash plumes.  A good analogy would be flying your airplane in front of a sandblaster.  It is something that's very, very hazardous for the operation of aircraft.

The other thing that's happened is we've had some disruption of production from some of the oil industry, oil production, in the Cook Inlet area associated with the eruption because of ongoing hazards to some of their facilities.  So, it really has been somewhat of an invasive eruption for us here in Alaska, beginning from March and continuing right up to the present.

04:04

Brian Campbell:  How is USGS Science helping to prevent this hazard from becoming a disaster?

John Power:  What we've really focused on is trying to give advanced warning of the eruptive activity that may be occurring and the hazards that it's going to pose.  We have a very detailed notification system that we've developed for working with other government agencies such as the FAA and the National Weather Service as well as local municipalities and industry, so that when the volcano does explode and puts out these large ash clouds, perhaps generates mud flows or lahars, everyone gets the word just as rapidly as possible and knows what to do in order to minimize the danger and hazard that they're experiencing.

Brian Campbell:  Wonderful.  And for you personally, John, what is the most interesting aspect of working on Mt. Redoubt?

04:59

John Power:  For me personally, Mt. Redoubt has erupted prior to this.  The most recent eruption was in 1989, 1990.  That was when I was a new, young scientist working for the USGS and was very involved in that eruption.  I feel fortunate to be able to come back and work on another eruption of the same volcano.  It's allowing us to take a good, hard look at some of the inferences that we made with the data from 1989, some of the models we put together for how Redoubt behaves and performs and why the volcano may erupt in this way.  It's providing a very, very interesting opportunity for us to really refine our ability to apply science to addressing natural hazards.

Brian Campbell:  Great.  And is there anything else that I forgot to ask that you would like to add?

John Power:  No, I think we've been pretty complete, Brian.

Brian Campbell:  All right.  Well, that's excellent, John.  Thanks again for agreeing to speak with us and we will certainly be in touch as we continue to monitor Redoubt.

06:00

John Power:  All right, Brian.  Yeah, if there's more I can help you with later on, certainly give us a call.

Brian Campbell:  Thanks, John, and thanks to everyone for tuning in.

This interview is a product of the US Geological Survey, Department of the Interior.