Q&A: Volcanoes and Tsunamis

Can volcanoes cause an earthquake? 

The two are definitely interlinked. During an eruption, the movement of the magma will definitely cause earthquakes and sometimes it can be pretty large. Like when I showed the example of Mt. Pinatubo, that was a very large eruption. They had magnitude five earthquakes all the time. So they can definitely cause earthquakes. The big earthquakes that you feel elsewhere in Alaska – those would not be caused by volcanoes. So it would only be in the vicinity of the volcano, but yes they definitely do cause earthquakes. - Guy Tytgat, Geophysicist, Alaska Volcano Observatory 

You mentioned that volcanoes create tsunamis by steep sides collapsing into bodies of water. When has this happened and where? 

That’s a good question. There is evidence but I can’t give you details because I haven’t done the research myself and I haven’t had time to read all about it. There is evidence that a small collapse, probably from Mt. Augustine in Cook Inlet, caused a small tsunami back in the 18 or 1700’s but I’m not 100% sure of the dates. I know some scientists are working on that. There has been Krakatoa, but that’s essentially a special case because Krakatoa is one of the largest eruptions that we have a record of and it was an island in Asia in the middle of the Indian Ocean. The eruption was so violent, that essentially, the island blew itself up and in the process, caused huge tsunami waves, which killed thousands and thousands of people in Southeast Asia. It was a very dramatic event. Again, it was in 1883, I believe. Volcanoes can definitely cause large tsunamis and again, like I said, it doesn’t happen very often. Of course the volcano has to be close to the ocean to create the tsunami as well. - Guy Tytgat, Geophysicist, Alaska Volcano Observatory 

How hot can the lava get? 

It depends on the lava but basically anywhere between 8-900° C to 12-1300° C and I’d have to make the conversion. Right off the top of my head, it’s probably around 2000-2300° F. Pretty hot. The temperature of the lava depends on its chemistry and it’s kind of an interesting point. I didn’t talk about it because I didn’t have all that much time but different types of lava will cause different types of volcanoes and different types of eruptions. I’ll quickly give two types of examples. One example would be Hawaii and I’m sure you’ve all heard about Mt. Kilauea and all those volcanoes in Hawaii. Those tend to be the kind that have very fluid lava and very hot lava. It will definitely get to 1200-1250° C. They’ll flow lava very fluidly but they don’t tend to have large explosions – mostly like I showed, lava fountaining earlier in the movie. Those kinds of eruptions.

The eruptions that we tend to have in Alaska tend to be more explosive. Those are caused by lava that is actually cooler – more like 8 or 900° C. It’s also very, very thick. It’s like paste. It doesn’t flow like a liquid like you see in Hawaii. It tends to flow in blocks and because it’s so thick, gas expands and finally gets out of the volcano. It tends to make it very explosive and that’s how you get explosions like Mt. St. Helens, which is a very good example of one of the eruptions that’s very explosive. So yeah, two different lavas, two different temperatures. - Guy Tytgat, Geophysicist, Alaska Volcano Observatory 

How big of an area will the ash plume affect? 

That’s a very good question because, depending on the size of the eruption, it could either affect just the volcano itself or it could affect the entire planet. There have been eruptions in the past. Tambora was one, Krakatoa – back in the 1800’s, and Katmai in 1912. Those types of eruptions are so large and they put so much ash in the atmosphere that they would actually circle around Earth with the winds and cause climactic change in essentially the entire planet. There was one instance, and I cannot remember which eruption it was, back in the 17 or 1800’s, there was actually a period of starvation in Europe because the crops wouldn’t grow because there was so much ash in the air that the sun was blocked and the temperature dropped by several degrees and hence, destroyed all the agriculture of the time. So it definitely can have a global impact on the entire planet. But those are for very, very large eruptions. It is not very common.

To give you an example, the eruption of Katmai in 1912. So Katmai is there on the western side of Cook Inlet, dropped ash as far as Africa. There was definitely a dusting of ash in Seattle. People were wondering what all that ash was doing on their boats and stuff. But actually, people in Africa detected some ash as well. So, it’s pretty impressive. It really brings that ash far away. - Guy Tytgat, Geophysicist, Alaska Volcano Observatory 

Are there any volcanoes in Fairbanks?

None in Fairbanks. The furthest north volcano is up in the Alaska Range, a pretty old one, and I have to admit to you to tell you the truth, I don’t remember the name because it’s not an active one so I’m not involved with it. But they go as high as the Alaska Range. Some geologists claim that Mt. McKinley, or Denali, should have been a volcano but it’s not. Due to its location, it would have been logical for it to be a volcano. But I repeat, it’s not a volcano. - Guy Tytgat, Geophysicist, Alaska Volcano Observatory 

What’s that highest, in elevation, height for a volcano? Do you happen to know what the tallest volcano is? 

The tallest volcano… That is a good question. I would think that the tallest volcano is probably in South America someplace. I know there is a volcano called Cotopaxi, which is about 18,000 feet elevation in South America, but I do not know if that is the highest or not. Definitely one of the high ones. Here in Alaska – the highest one in Alaska is Mt. Wrangell. That is kind of in the eastern part of the state. A very, very large shield volcano and it reaches about 14,000 feet. - Guy Tytgat, Geophysicist, Alaska Volcano Observatory 

While you’re on the subject of shapes of volcanoes, you mentioned shield volcanoes, and could you describe the other shapes too please?

Sure. The basic two shapes are the shield volcanoes and the stratovolcanoes. The shield volcano example is Hawaii. Hawaii tends to have those big, broad, very large, but rather flat, although they grow pretty high in elevation but they’re so broad that’s how they reach the height and their shape tends to be flatter. Those occur when we have fluid lava like they have in Hawaii. It tends to be this hot lava and it flows down. Since the material itself… It’s kind of an angle (of approach?) type of problem. If the material is very fluid it will tend to spread out pretty easily.  If the product of the eruption is pretty blocky, it’ll tend to create a pretty steep mound and this is the case for the stratovolcanoes where the lava is much thicker. It comes out in blocks and they tend to pile up pretty steeply. We call them stratovolcanoes because they create layers during each eruption.  Of course in between, you have different kinds. 
Well, I mentioned the caldera, which is essentially a very large volcano, which collapses on itself. All that’s left is a big cauldron, which is where the word “caldera” comes from. It’s a big, flat area surrounded by very steep walls and within that you will have newer volcanoes emerging so you’ll have small vents within the volcano.

You can have complex volcanoes, which tend to be volcanoes kind of building on each other.  So you have several cones – not one beautiful cone like Mt. Shishaldin or Pavlov in the Aleutians, which are those perfect-shape volcanoes. But then there’ll be those complicated-shaped volcanoes that have all kinds of craters.

They also have maars. Maars are not really volcanoes, per se; they just tend to be big lava fields. There have been eruptions like that maybe thousands, maybe millions of years ago, which would cover the size of a state in the lower 48, with lava. They have those huge lava flows extend over huge areas. They tend to come out of Maars, which is kind of an area, which is really, not even a mound – just kind of a hole in the ground and the lava just kind of flows out of it. Let me see if I can think of any other kinds. I can’t think of any other kinds right now. But again, there are all kinds of shapes and what differentiates them is the magma composition and things like that. 

Because we are talking about the different shapes of the volcanoes, there are also different types of eruptions. You have what we call a phreatic eruption. A phreatic eruption is basically water from rain or snow that is basically percolating through a volcano and it reaches a point in the volcano where it’s so hot, it turns into steam, and then the steam will violently explode. These typically don’t make huge eruptions but they make sizeable explosions. Those, we call phreatic eruptions.

Then you can have strombolian eruptions. Strombolian eruptions are named after a volcano called Stromboli in Italy. It’s a volcano that’s erupted for hundreds of years constantly, and it’s not large eruptions, it’s just small explosions with lava coming out and it’s been happening for, like I said, for hundreds of years. So that’s what we call Strombolian eruptions and they’re low-key eruptions that occur for long, long periods of time.

Then you can have Hawaiian-type of eruptions that tend to involve a lot of lava pouring out of the volcano, and very liquid. We have vulcanian eruptions. Again, it’s named after a volcano in Italy. It creates slightly bigger eruptions then the strombolian – explosive but not huge. Then we get into eruptions called pelean eruptions and those tend to be those very large, explosive type of eruptions like Mt. St. Helens and Mt. Pinatubo, and Vesuvius, in Italy, which burned the town of Pompeii back in 50 AD or so. So there are all types of eruptions like that – from the very small ones to the very large ones. - Guy Tytgat, Geophysicist, Alaska Volcano Observatory 

If you have a lava flow that’s continuously flowing from the Earth, does that create a cavern?

That’s a very good question. I didn’t talk about that again, because I didn’t want to get into too much detail. Beneath a volcano, before you get an eruption, essentially you have lava rising between anywhere from one and five kilometers in depth and it will fill what we call a magma chamber. So essentially, it’s a big cavern, a big cavity, that’s full of lava that contains gases and molten rocks. When there’s a large eruption, all that lava will rise to the surface as a big explosion or as you mentioned as a lava flow. But as the lava is leaving, it’s kind of leaving a void and what happens occasionally is the floor of the volcano, or the crater of the volcano collapses because now there is nothing to support it underneath and once the lava is all gone, it’ll collapse and it’ll form what we call a caldera. Essentially, a caldera is a very large crater. Essentially, what it is is the volcano has collapsed on itself because it left a huge void underneath. So definitely, as the lava comes out, it leaves a big void that has to be filled somehow. That’s one of the ways it fills up. Those seem to be from very large eruptions. For a small eruption, like we had on Augustine, there’s no crater collapse. What happened was that the volcano would actually inflate before eruption and as the eruption happened, the volcano deflates again and goes back to its normal shape because the magma chamber is actually within the volcano itself. That’s one thing that the GPS is very useful for, is to measure this inflation of the volcano. If we see that it’s inflating, that gives us an alarm that this volcano is about to erupt. - Guy Tytgat, Geophysicist, Alaska Volcano Observatory 

I’ve noticed articles, particularly National Geographic, about robotic equipment being used to examine interiors of volcanoes. Are you involved with that at all, or can you tell us a little bit about that use? 

We were a few years ago when a group came up to test their robot. The robot’s name was Dante. They brought the robot to Alaska. Mt. Spurr had just erupted so that was back in 1992. Essentially, they wanted to see if it was feasible to send a robot, to take for example, rock samples, or do things like that in an area where, for obvious reasons, was way too dangerous for a human being to go. Unfortunately, they ran into technical difficulties. It’s obviously something that is, technically, very challenging and the robot wasn’t able to go very far and then they ran into problems and they had to bring it back. But there are definitely more and more attempts at using robots because, like I said, it’s very dangerous and not just because of the eruption. And again, I go back to the fact that volcanoes tend to be very crumbly. They are not very stable, and so you can find yourself where the volcano is not erupting at all and yet the whole side of the volcano could be sliding down in an avalanche, or you could have a rock falling from above. There’s a lot of steep terrain on volcanoes. So all those are very hazardous, so robots would be very useful.

One thing they did on Mt. St. Helens, that they are doing right now, actually, it’s not a bad system, it’s not a robot, but it’s an instrument that they can lower down using a helicopter without putting anyone on the ground. In other words, you don’t put people at risk by putting people on the ground. So they just lower down the instruments. You’ve got the helicopter hovering and they have a cable and they lower the instruments all the way down to the ground and the instrument levels itself, and then transmits the data back to, in that case, to Vancouver and Washington. That works pretty well because the Mt. St. Helens dome is pretty active and pretty dangerous. You could never send a technician out there. Yet, it would be interesting to have instruments. That’s one of the systems that they found. But robots, like they’ve used on Mars and stuff, they tend to be very costly and very fragile so they’re still working on that. I’m sure that they will have some of those. - Guy Tytgat, Geophysicist, Alaska Volcano Observatory 

Are they anticipating a possible eruption [of Mt. St. Helens] within the decade? 

Well, it is kind of erupting right now. I mean it’s been pretty active over the last three or four years. They’ve had small eruptions, of course, nothing the size of the initial eruption back in 1980. But large enough that you wouldn’t want to be anywhere near that crater when it erupts. I had a few videos. I don’t know if I took them with me or not. Essentially they have a time-lapse camera that sits there in front of the volcano. It takes a picture every thirty seconds or something and it had a time-lapse where you could see one of the eruptions occurring early in the morning, but unfortunately I didn’t bring it with me. But those tend to occur fairly often actually. So it’s definitely pretty active. But as far as a large eruption, probably not very soon because I would suspect that more magma would need to rise to the surface in order to create a large eruption like that. - Guy Tytgat, Geophysicist, Alaska Volcano Observatory 

You gave a list of all the volcanoes, lahars, and pyroclastic flows. I guess my question is: Could one, single volcano be an explosive volcano which turns into a plume or …

You can have a volcano that takes on all the hazards. It’s the combination of all those hazards. Some are more capable of certain hazards like Hawaiian volcano would certainly be more hazardous because the lava is pretty fluid there, but there would be less danger for an ash plume because Hawaiian volcanoes don’t produce large ash plumes. In order to have pyroclastic flows you need the material to cause it so some volcanoes will have it and some others wouldn’t. But yes, definitely they would cause more than one hazard at a time. - Guy Tytgat, Geophysicist, Alaska Volcano Observatory 

I guess what I was think was Mt. St. Helens. Was it a lahar or pyroclastic flow? 

Mt. St. Helens and Mt. Pinatubo are good examples of ash plumes going very high in the atmosphere causing problems for aircraft. Explosions, even if you are not near the volcano, can still be heard.  Definitely pyroclastic flows, several people died in the eruption of Mt. St. Helens because of pyroclastic flows. Ash fell on buildings causing them to collapse or potentially hurting people. Mud flows or lahars were definitely a big problem with Mt. Pinatubo and were somewhat of a problem with Mt. St. Helens. So definitely, yes. - Guy Tytgat, Geophysicist, Alaska Volcano Observatory 

Did you mention something about a volcano in Antarctica? 

That’s correct. There’s actually more than one but the one that I showed is very active. It’s actually one of the few volcanoes in the world that have an active lava lake which means that the bottom of the crater has a lake that is made out of lava and it’s bubbling. It’s interesting that it happens to be in one of the coldest places on Earth but it’s a very, very active volcano. There are a couple other ones too but they don’t have the same level of activity. - Guy Tytgat, Geophysicist, Alaska Volcano Observatory 

I know none of you where around the last time you had a really big volcano, but do you remember your parents or grandparents telling you any stories about when that happened; the Mt. Katmai eruption?

Three days of night, my granny told my dad. -Teri Schneider, Teacher, Kodiak Island Native and Rural Education Program

My great grandmother came from Mt. Katmai. They left their village when that happened. - Teresa Carlson, Kodiak Community Member

I heard they brought a lot of people to Afgonak from Katmai and to different place on Kodiak. - April Laktonen Counceller, Quk'rtarmiut Alutiit Language Revitalization program manager, Alutiiq Museum & Archaeological Repository

Yeah, we were from the area, new Afognak. There were a lot of people in Afognak. I don’t know why they moved to a place like that, all reefs. I guess it was because of the clams. - Dennis Knagin, Kodiak Elder 

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