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CNN Live Sunday

Interview With Vulcanologist Tom Sisson

Aired January 27, 2002 - 22:42   ET

THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.

THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.
CATHERINE CALLAWAY, CNN ANCHOR: The misery created by the volcano in Congo may seem like a world away, but the U.S. has certainly seen its share of volcanic destruction as well, and will see possibly more in the future. Well, joining us now for some educated guesswork is Tom Sisson. He's a vulcanologist with the U.S. Geological Survey. And thank you very much for being with us this evening.

TOM SISSON, USGS VULCANOLOGIST: Thank you.

CALLAWAY: First, I guess the question everyone wants to know, is there a real threat domestically in the U.S. of a volcanic eruption in the near future?

SISSON: Well, of course. Kilauea Vulcano, which, as you know, is in the United States in Hawaii, has been in nearly continuous eruption for 17 years. So, we have erupting volcanoes in the United States.

In addition to Kilauea, there are a large number of volcanoes in Alaska, which erupt every year. The most recent of those was Mt. Cleveland, which was last February.

CALLAWAY: This now we are showing from the USGS.gov potentially active volcanoes in the Western U.S. We're looking at it while you speak. Continue, please.

SISSON: All right. But closer to home -- in the continuous United States, the most potentially destructive volcano we have Mt. Rainier, which is in southern (UNINTELLIGIBLE) region. And it's not most destructive because it erupts most frequently -- that would be Mt. St. Helen's -- it's most potentially destructive because of the large number of people who live around it. There are about 150,000 people who live on volcanic mudflow deposits from Mt. Rainier that have been unleashed from the volcano in about the last 6,000 years.

CALLAWAY: Tom, how difficult is to predict an eruption, and what are the signs?

SISSON: Well, usually when a volcano is getting ready to erupt, there will be a period of days to months of focused earthquakes underneath the volcano. So we may have a window of warning as long as several months or as short as a few days. We can't predict it any longer term than that. CALLAWAY: What about satellite imagery? Is that effective at all in telling you any changes that could indicate that there is going to be an eruption?

SISSON: Well, satellite imagery has been an important new area for studying volcanoes. It's been useful in two respects. One, is to detect eruptions of remote volcanoes and track their eruption clouds, and the other is to see swelling of the ground that can be precursory to a volcanic eruption. And an example of that would be an area near the Three Sisters in Oregon, which was only recently discovered to be undergoing ground deformation and uplift. We don't know if that will lead to an eruption, but we're certainly keeping a close eye on it.

CALLAWAY: Tom, how difficult is it to get people -- for instance, people who live near Mt. Rainier, when you say it looks like there may be an eruption in the future, do they take it seriously? I mean, it's difficult for most of us to believe that domestically that could happen here.

SISSON: Well, we have a trump card, at least in the Pacific Northwest, and that was the May 18, 1980 eruption of Mt. Saint Helen's. So people in that area take volcanic eruptions seriously. They know that they can happen, they know that they can be very devastating. And public officials, the public at large and emergency management staff have been very responsible and responsive about developing plans, contingency plans for when their volcanoes wake up again.

CALLAWAY: And when do you think that would happen in the U.S.? I know there is some sense of a time clock for these eruptions -- every couple of thousand years, or?

SISSON: Well, the volcano which is most likely to erupt again in the continuous 48 states is Mt. Saint Helen's, and that's just based on how frequently it's erupted in the past.

After that, it would perhaps be Lassen Peak in Northern California, which erupted as recently as 1915. It could be Mt. Shasta -- Mt. Shasta has erupted every 200 to 300 years.

So, any one of those volcanoes could be the next to erupt in the lower 48 states. But as I said before, potentially the most dangerous, when it does erupt, will be Mt. Rainier.

But the last big mudflow that's come off of Mt. Rainier was 500 years ago. Prior to that, there was a large mud flow that came off of Rainier about 1,100 years ago, and prior to that about 2,200 years ago. So we are talking about low frequency, high impact events -- and that aspect is difficult to plan for.

CALLAWAY: Tom Sisson, thank you very much for joining us and giving us a lot of insight on volcanoes here in the U.S. Thank you.

SISSON: Thank you.

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