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Tanzanian Villagers Encouraged to Learn Hazards of Living Near Erupting Volcano

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Audio interview with USGS scientists regarding the Ol Doinyo Lengai volcano in Tanzania.


Public Domain.



Clarice Nassif Ransom: Welcome to this interview with USGS scientists Gari Mayberry, Thomas Casadevall and David Sherrod to discuss their recent trip to Tanzania and their hazard assessment on Ol Doinyo Lengai volcano. I'm Clarice Nassif Ransom, your host.

Thank you for joining us. Tell us a bit about what you discovered at the volcano.

David Sherrod: Well we were at Ol Doinyo Lengai in January; we found the volcano in relative repose. Any volcanic activity at the time was limited to lava that was deep in the summit crater. A rainy season that had occurred prior to our arrival had brought the grass back through much of the area where ash previously had probably knocked it down and killed it.

The Masai villagers were herding their cattle across the flanks of this volcano, a very pastoral setting. The volcano's west flank is blanketed by ash as thick as six or seven inches; rain has caused that ash to form an almost summit-like surfaces scab on the earth's surface. And there, the vegetation is buried and completely dead.


Clarice Nassif Ransom: What is the current status of the volcano?

Thomas Casadevall: Ol Doinyo Lengai, as David had already said, experienced a period of explosive eruptions between September of 2007 through April of 2008. Some of these explosions produced ash columns that rose for more than 50,000 feet above sea level and with the dominant wind direction, the ash was largely carried to the west.

Since 2008, the volcano has been relatively quiet with then frequent smaller explosions. Current activity is confined to the north summit crater, and as David pointed out, the volcano is located in a very remote region with fewer than 10,000 permanent residents living within 10 kilometers of the volcano.

Currently, the volcano has no monitoring of earthquakes, deformation or gases. And the rainy season which is coming up for May through October, rains will cause and trigger mudflows and flash floods.


Clarice Nassif Ransom: How will that impact the community around the volcano?

Thomas Casadevall: The main issue is that the road system, the infrastructure, in this area is very rudimentary. The road access in the volcano is gravel roads. They are not necessarily very well maintained and during the rainy season, the floods will come through and basically wash out the road. There will be periods of days when vehicles and buses won't be able to get in to serve the small communities around the volcano.

Clarice Nassif Ransom: What are the social and economic disruptions posed by an eruption at this volcano?

Gari Mayberry: Well as David and Tom have said, there has been explosive activity in 2007 and 2008 and there are a few villages that are relatively close to the volcano and they had been affected by ash fall from the explosions. And during the height of the explosions, these villagers had to evacuate and many of the people there subsist off of their cattle and so they also had to find places for their cattle to go and they weren't able to graze because the graze land was covered by ash. So the water supply was contaminated.

These people who evacuated were sometimes separated from their families temporarily and some are still displaced from the area. More generally, tourism in the area was impacted.


Clarice Nassif Ransom: What is the USGS doing to respond?

Gari Mayberry: Well much of the USGS response have occurred already. We received a request from the government of Tanzania in late December for assistance, and we sent over a team, the three of us, to respond to that request, to see what was going on at the volcano and to see if we had any advice for how they could do some early warning.

As Tom said, there is currently no equipment monitoring at the volcano so they wanted assistance with that. We provided some findings of recommendations from our trip that the government is now reviewing, and based on the feedback from that report, there may be some more things that the USGS are supposed to respond.


Clarice Nassif Ransom: So overall, how is USGS science being used by the government of Tanzania?

Gari Mayberry: Well, as part of our visit, we did a preliminary hazard assessment and so we just tried to take a look at past deposits and to get a feeling of what happened in the past to see what might happen in the future. And so we have provided with the government with the results from that preliminary assessment.

In addition to science, the USGS experience I think has also been used by the government. Some of the lessons that we have learned from having several volcano observatories here in the United States, we tried to give them some advice from what we've learned from these observatories with some things that they can do with the resources that they currently available to them.


Clarice Nassif Ransom: Terrific. Can each one of you describe your most memorable experience about this trip?

David Sherrod: Any time any of us get to travel abroad, this is a lesson in culture and sociology in our own civics. Tanzania has a thriving middle class; they are intelligent and capable people. This is something you cannot determine without going to see a country.

We were able to travel into a foreign country but not be tourists. We were working with professional comrades there of that country. We were brought into their lives in ways that gave us greater intimacy with their culture and lifestyle.

From a geologic point of view, for me, working with Tanzania colleagues in a terrain that very closely resembled the basin rains of the United States, that is an inherent part of the nation there, it is crossed by large earthquake faults, large escarpments, topographic escarpments. Much of it was just like a country I have seen in other places, except for the giraffe and the zebra and wildebeest and elephants, I haven't dealt with those kinds of animals before while working in the United States.


Clarice Nassif Ransom: Tom?

Thomas Casadevall: I chime in with what Dave said. I think he hit on the head. The three things that really jumped out of me that will stay with me forever: I think working in an area of a very unique culture, the Masai culture, the Masai came into Kenya and Northern Tanzania about two centuries ago and they are now the dominant culture in this very arid environment where we were working in the rift valley.

So working in the area of the Masai culture or the Masai pastoralist, meaning that their main wealth and the status in their society is tied up in the cattle and the donkeys and the goats and the sheep, that they are responsible for. And that is why this eruption has such an important impact on the Masai culture. As Dave pointed out, the ash fall caused dieback of the vegetation, which was critical for raising of these particular animals. So the Masai culture was really a big point for me.


On the wildlife side, the first time you see a herd of zebra or that you see giraffes prancing across the road in front of you, it is just a remarkable thing that I've never seen in the wild before. And that made a big impression.

Then I think the third thing is we happen to be there on January 20th, which of course is the day of the inauguration for the new U.S. President. And of course, this president had relatives; his father came from Kenya just to the north of the area where we were working. That evening at 8:00 at night in the small village where we were staying, the village had no electricity so they brought in a power generator, someone brought in a television and we are still not sure where the TV signal came from but at 8:00 at night with several hundred people from the village including some Masai people, we watched the inauguration of our 44th president which was a remarkable experience for me.


Clarice Nassif Ransom: That is terrific. What about you, Gari? What's your most memorable experience about this trip?

Gari Mayberry: I think there were two main experiences that really stick out for me. One was just going to visit this volcano which I have just read and heard so much about. Ol Doinyo Lengai is a very unique volcano, the only one like it in the world, so it was just a real thrill for me to get there and to see the volcano.

Secondly, as Dave and Tom had said, really the human element will really stick with me. Just seeing how people are living near the volcano, it was a very hot arid climate and people lived off of their cattle and really, their jobs are to walk around this extremely hot harsh environment with their cattle. And life just is a daily struggle to get water and to get food for their cattle. Then on top of that, every once in a while, ash falls on them to make things even harder, and that is just the sort of thing that I don't think you can get a real grasp of unless you're there seeing it happen. Reading about it is just not quite the same, so that is definitely going to stick with me, meeting these people and seeing how they are living with this volcano.


Clarice Nassif Ransom: So what are the next steps?

Gari Mayberry: Well as I've said, we've provided the government of Tanzania with some recommendations. We had to help them to deal with the Ol Doinyo Lengai volcano. One of them was this volcano hazard assessment which they will review and possibly decide if they would like to do a more in-depth study.

Another thing that we're going to be able to work on while they're reviewing the more longer term strategy is analyzing some of the ash that we received from our colleagues from the geological survey in Tanzania to learn more about its chemical makeup and the impact it may have on people's health.


Then also, the International Volcano Health Hazard Network has produced some pamphlets that discuss how to deal with ash fall. We are going to work with our colleagues from the University of Dar es Salaam in Tanzania who have offered to translate these pamphlets into Swahili so that local people living near the volcano can learn more about how they can deal with this hazard. It may go on to be translated into Maa, the local Masai language.

But I think the most important thing, the most important next step, is that we're going to maintain the relationship that we've built with our Tanzanian counterpart. I think that was one of the main accomplishments from this trip. It was to meet with scientists from the geological survey there and from the universities who have been dealing with the volcano and continuing our relationship beyond this trip.


Clarice Nassif Ransom: Tell me a little bit about the USGS volcano disaster assistance program and why you think it's important.

Gari Mayberry: I think one of the best ways to understand the volcano disaster assistance program is to know a little bit about its history. In 1985, there was an eruption of a volcano called Nevado del Ruiz in Colombia, and it was a relatively small eruption. There was lava emitted but this lava melted part of a glacier on top of the volcano which produced large mudflows that traveled tens of kilometers away from the volcano and inundated the town of Armero and killed about 25,000 people.

I just really felt like this disaster could have been avoided if there was proper communication about the hazard to the people in the town. They could have evacuated to higher ground. And so the realization that science could really help these local volcano observatories in dealing with their own rest led the USGS and the US Agency for International Development's Office of Foreign Disaster Assistance to form the Volcano Disaster Assistance Program.


Clarice Nassif Ransom: Great. Is there anything that any of you would like to add that I may have forgotten to ask about this trip or about the volcano disaster assistance program?

Gari Mayberry: I just want to stress what a unique situation this was in many aspects. A VDAP team was called in after the height of activity. It was an opportunity to thoughtfully look at how a local government might be able to deal with their hazard.

Also, we usually don't deal with volcanoes that have absolutely no monitoring, so it kind of forced us to look at the situation in a new way and to determine that disaster risk reduction education may be the most feasible way to reduce the hazard because it will be quite difficult due to the lack of infrastructure in this particular region to install monitoring equipment.

Also, as I said earlier, this was a very unique volcano, the only one like it that is active in the world, and so it was just a unique experience in many ways.


Thomas Casadevall: Another point to make is that this request came to USAID, to the USGS from basically the president of Tanzania. Although it hasn't been said in the interview so far, I think it's very important to point out that at the end, Gari Mayberry, our lead on the visit, actually had an audience with President Kikwete, the president of Tanzania. That is a rather important factor that I think puts a fine point on Dave's point about the fact that we have the opportunity here to project US presence and US goodwill to the highest levels of the government, in this case in the Tanzania.

Gari Mayberry: It's quite interesting. During my meeting with the president, he was quite in-tune with the issue and he was very interested in our findings and our recommendation. And he was also quite eager to discuss his experience with the volcano.


Clarice Nassif Ransom: Two follow up questions: Tell me a little bit about the president's experience with the volcano. And then the other question was going to be about, I don't how you put it but it was something about it being one of the most unique volcanoes in the world and it's one of a kind. For a lay person, what does that mean, a one of a kind volcano?

David Sherrod: The uniqueness of Ol Doinyo Lengai stems from the fact that this is the only volcano in the world that has erupted in the last 100 years. A lava type that is known as carbonatite, the "ite" on the end, the "ite" part simply indicates that it's a rock. So the kind of lava that comes out of this volcano, this carbonatite lava is essentially carbon dioxide lava. That carbon dioxide is the principal component of this lava and it mixes with sodium and potassium to make this thing into a fluid.

We don't get this kind of lava at Hawaii. We have a lot of it coming out of the ground in other places in the United States and around the world, at Etna, you name your volcano. None of those volcanoes can produce this kind of lava.


The reason we think it's here is because the east African rift is trying to tear apart the continental crust, the lithosphere of Africa. It is having a hard time doing that. The magma is probably saturated in one of the very common volcanic gases and that's carbon dioxide. It's stalling, trying to get to the surface and is being able to hold enough of this carbon dioxide within it that this actually forms, separates as a separate part of the total magma system, much like vinegar and oil don't mix. If you can increase the carbon dioxide content enough, you can separate this carbon dioxide as a separate part of the melt, little bubble minuscules of CO2 liquid.

This volcano erupts this stuff; it is weird. This is lava that is so low on the temperature scale that it almost doesn't glow red. It has a hard time igniting trees or grasses as it flows over it because it's right at the point of ignition temperature from any of the things that grow on the surface of this volcano. So it just makes it a really strange kind of volcano worldwide.


Clarice Nassif Ransom: That's cool.

David Sherrod: Gari, with your president experience stuff, I want to hear about it.

Clarice Nassif Ransom: Yes, I want to hear about your experience with the president and what he said. You said he got excited because he wanted to also share his experiences with this volcano.

Gari Mayberry: Yes. I just think people find volcanoes as really fascinating and if they've had an experience with it, I find that they really like to share that with you and if they find out you're a volcanologist, and the president was no exception.

He shared that he is an avid animal watcher and there are ample opportunities to do that in Tanzania. Ol Doinyo Lengai is located near the Ngorongoro Conservation Area which is near Ngorongoro crater, which has an abundance of wildlife. And the president has traveled in that area quite a few times to do some animal watching, and he said he was near the volcano. I'm not sure what the timing was but he said that he noticed that there were a lot of animals but not on the volcano. And he thought perhaps that's because the animals could sense that they're going to be eruptive activity.


But by the end of our discussion, he thought that it makes more sense that there had been ash fall recently on the grassland near the volcano and so the animals probably were not going there because they didn't want to eat the grass that had ash on it.

Then another story that he shared was that once he was flying past the volcano and it was erupting and it had an eruption cloud and he thought that was pretty cool, and he asked the pilots to go closer so he could see it better but they would not go closer. So in the course of our discussion, he learned that the pilot did a wise thing because it can be very dangerous for aircrafts if they fly into an ash cloud. That ash can cause the engines to fail, and there have been several encounters around the world where this has happened and the engines have lost power, and how it descended tens of thousands of feet before being able to restart the engine and so it's best for aircrafts to avoid ash clouds. By the end of our conversation, that is when he understood why the pilot would not go closer but he appreciated that he did.


Clarice Nassif Ransom: That's terrific.

Thank you for joining us, Gari, Tom and David. Thanks to all of you for listening to this interview which is a product of the US Geological Survey, Department of the Interior.

Until next time, I'm Clarice Nassif Ransom.

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