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Kasatochi Volcano Erupts Explosively

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Kasatochi Volcano in Alaska's Aleutian Islands is erupting, so USGS volcano scientist Marianne Guffanti fills us in on the situation.




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Clarice Nassif Ransom: Welcome and thanks for listening to the USGS CoreCast. I’m Clarice Nassif Ransom. Kasatochi Volcano in the Aleutian Islands of Alaska erupted explosively on August 7th, sending an ash from 45,000 feet into the air and causing two U.S. Fish and Wildlife Service employees to be evacuated from the island.

Kasatochi marks the third Aleutian Island volcano to erupt explosively in three weeks. Okmok volcano erupted unexpectedly July 12. And nearly 100 miles away, Cleveland volcano erupted July 21st. Scientists are working around the clock to let the public know what is going on.

I’m here today with Marianne Guffanti, a volcano expert with the U.S. Geological Survey to discuss the situation. Thanks for joining me Marianne. Tell us what’s happening at Kasatochi.


Marianne Guffanti: Kasatochi is still erupting. It’s getting on its eruption from August 7, ashes going to about 30,000 to 45,000 feet in burst and in drifting. The long distance is in the atmosphere. We also just learned that the two Fish and Wildlife Service biologists that were on the island were safely rescued just about an hour before the eruption began.

Clarice Nassif Ransom: Wow. That’s amazing.

Marianne Guffanti: Yes, it was a very close call. We’re very, very thankful that they were rescued by a commercial fishing boat.

Clarice Nassif Ransom: Kasatochi is the third volcano to erupt in three weeks in Alaska. What’s going on?

Marianne Guffanti: Well, the number of three eruptions isn’t so unusual. Typically, in Alaska, there may be two to three eruptions per year. But the close spacing within three weeks has certainly increased the workload of the Alaska Volcano Observatory and the Coast Guard and all the others who are involved in responding to this kind of emergency.

Clarice Nassif Ransom: What does USGS trying to respond? Explain that a little bit to us.

Marianne Guffanti: The USGS offer its five volcano observatories within the Unites States, and one of those is the Alaska Volcano Observatory. So they are doing their best to collect all of the data on these volcanoes as they can and watch the eruption. They are hampered by the fact that there are no instruments right on the island.

Clarice Nassif Ransom: How important is instrumentation?


Marianne Guffanti: It’s very important. Satellite imagery is useful for seeing a big picture of what’s going in to the atmosphere. But it can’t really see what’s happening before the volcano erupts. And it’s hampered by nighttime and the clouds and things like that. So we really need geophysical instruments like seismometers and the formation sensors on the island to see that early phase of unrest that’s leading up to the eruption so we can give everybody a much longer warning.

Clarice Nassif Ransom: How is USGS Science being used by the public and by emergency responders in all of these instances?

Marianne Guffanti: Whenever we have information about a volcano that’s either showing signs of unrest or erupting, we issue formal advisories, watch these warnings and color-coded – now, this is for aviation, to alert people to the seriousness, how serious we think the conditions are of the volcano. People can use that information and adjust their behavior accordingly. In this case, when we went from normal to advisory or to yellow, it was a signal that there is – biologists were in danger and they need to be removed from the island.

Clarice Nassif Ransom: Is there anything that you would like to add that I may have forgotten to ask?


Marianne Guffanti: Well, Kasatochi is yet another example of a very important lesson that we learned in volcanology. And that is that we don’t necessarily have much time from when a volcano first show signs of unrest and when it can erupt very explosively. In Mount St. Helens in 1980, we had two months from the start of unrest to the big eruption. We’re learning around the world and again here in Alaska, but that’s not always the case. So we really need to be ahead of the curve on these events to give people the greatest warning.

Clarice Nassif Ransom: Great. Thank you for joining us, Marianne.

Marianne Guffanti: You’re welcome. My pleasure.

Clarice Nassif Ransom: You can find out more information about the USGS Volcano Hazards Program at CoreCast is a product of the U.S. Geological Survey Department of the Interior. Until next time, I’m Clarice Nassif Ransom.



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