Other times, the bench slowly sinks, submerging lava tubes formed above sea level. Sometimes these collapses expose a lava tube out of which lava pours like water from a hose. The benches are not well supported and can fall off into the ocean. When the lava reaches the coastline and enters the ocean, it often forms benches where lava builds out on top of coarse black sand beyond an older coastline. The lava in the tubes remelts the old surface, creating large tunnels that carry the lava stream towards the coastline. Sometimes we can look into skylights (openings) in the roof of a tube and see large bubbles breaking on the lava surface. The lavas are far less bubbly at this stage than when they first came out at the vent, because a lot of gas has escaped into the air, but they can still be more than 30 percent bubbles. In either case, a roof eventually forms over the channel, making a lava tube.Ī tube insulates the lava inside so that it can stay hot and fluid as it flows away from the vent. It may take a while for a channel to develop or it may happen almost immediately. The lava then tends to form channels that carry the fluid lava away from the vent, thereby beginning a lava flow. The lava is more like foam, and the pahoehoe that forms when the lava cools is very "shelly" so-called because walking on it is like walking on large egg shells. When lava first comes out at the vent, it is highly charged with gas - so much so that the lava is more than 85 percent bubbles. “I was always interested in science,” he says, “and in geology, I found a science that incorporates a little bit of everything.How do pahoehoe lavas flow? Over the years, many scientists have watched and measured active lava flows, and now we have a pretty good idea of the process in Hawai`i. The next stop for Kolzenburg and his team is Lassen Volcanic National Park in northeast California, which features several types of volcanoes. “And we can better understand when it cools and turns back into rock again.” The equipment can work with material as hot as 1700° C. “We can melt rocks, stir them around and measure how hard it is for this material to flow,” he says. In LAVAP-UB, Kolzenburg’s lab, sophisticated equipment allows controlled study of molten rock. The satellites use heat sensors that can tell us how much magma is coming out of the ground and where it is, and we can use that information in the models.” The model will be a tool that can be adapted to predict lava flow rates at other sites. When the next eruption comes along, we want to integrate the model with satellite data recorded by collaborator Diego Coppola at the University of Turin. “At Nyiragongo,” Kolzenburg says, “we want to collect enough data to optimize a model for that specific volcano in collaboration with Oryaëlle Chevrel from the Université Clermont Auvergne. Magma is the molten rock found beneath the earth’s surface once it breaks through to the surface, it’s considered lava. The viscosity also varies as the lava slows and cools until, finally, it hardens into rock. Lava’s viscosity depends on the location of the opening where the lava flow begins, the terrain and the composition of the lava. Viscosity is the measure of how hard it is for a fluid to flow. “We’re interested in the viscosity of the lava because that will determine how fast and how far it will go.” “We want to measure flow properties of lava while it’s hot,” Kolzenburg says. Additional fieldwork collaborators William Moreland, Ármann Höskuldsson and Thor Thordarson from Háskóli Íslands (University of Iceland) joined them. When Litli-hrútur in Iceland erupted on July 10, one of Kolzenburg’s PhD students, Martin Harris, immediately packed up a field rheometer prototype developed in Kolzenburg’s lab and flew to Iceland with it to meet collaborator Oryaëlle Chevrel, who has developed a complementary rheometer prototype at the Université Clermont Auvergne in France. While the research will focus on these volcanoes, Kolzenburg expects their findings will contribute to a better understanding of volcanic rheology - the term “rheology” comes from the Greek word for “flow.” This work involves a junior researcher from the Goma Volcano Observatory, Albert Kyambikwa, who is a graduate student in Kolzenburg’s laboratory. Kolzenburg, assistant professor of geology, College of Arts and Sciences, earlier this year received a $410,626 grant from the National Science Foundation to study Nyiragongo and another nearby volcano, Nyamulagira.
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