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Define viscosity volcano1/11/2024 ![]() The low viscosity of the lava means that it can flow for long distances, resulting in the greater size of shield volcanoes compared to composite volcanoes or cinder cones.įigure 11.23 Shield volcano. Shield volcanoes, like the Sierra Negra volcano in the Galápagos Islands (Figure 11.23, top), get their gentle hill-like shape because they are built of successive flows of low-viscosity basaltic lava (Figure 11.23, bottom). Cinder cones have straight sides, unlike upward-steepening composite volcanoes, or rounded shield volcanoes. It rises 172 m above the landscape, and has a diameter of under 500 m. Eve Cone is a cinder cone on the flanks of Mt. Unlike shield volcanoes, composite volcanoes have a distinctly conical shape, with sides that steepen toward the summit.Ĭinder cones are the smallest, and almost too small to see next to a volcano like Mauna Loa. Composite volcanoes tend to be no more than 10 km in diameter. It rises 1,356 m above the surrounding terrain in the Cascade Range of the western United States, and has a diameter of approximately 6 km. Helens is shown on the left of Figure 11.22. Kīlauea Volcano rises only 18 m about the surrounding terrain, and is almost not visible in the scale of the diagram, however it still stretches over a distance of 125 km along the eastern side of the Island of Hawai‘i.Ĭomposite volcanoes are the next largest. Kīlauea Volcano is also a shield volcano, albeit a much flatter one. Source: Karla Panchuk (2017) CC BY 4.0 modified after Steven Earle (2015) CC BY 4.0 view original Straight-sided cinder cones are the smallest, and barely visible in the scale of the diagram. Broad, rounded shield volcanoes are the largest, followed by cone-shaped composite volcanoes. Figure 11.22 Comparison of volcano sizes and shapes. In total, Mauna Loa is a 17,170 m thick accumulation of rock. Furthermore, the great mass of the volcano has caused it to sag downward into the mantle by an additional 8,000 m. It rises up from the ocean floor at a depth of approximately 5,000 m. The summit of Mauna Loa is presently 4,169 m above sea level, but this represents only a small part of the volcano. Figure 11.22 shows the largest of all shield volcanoes- in fact, the largest of all volcanoes on Earth- Mauna Loa, which makes up a substantial part of the Island of Hawai‘i and has a diameter of nearly 200 km. Shield volcanoes, which get their name from their broad rounded shape, are the largest. Figure 11.22 illustrates the size and shape differences amongst these volcanoes. There are three types of volcanoes: cinder cones (also called spatter cones), composite volcanoes (also called stratovolcanoes), and shield volcanoes. ![]() Individual volcanoes vary in the volcanic materials they produce, and this affects the size, shape, and structure of the volcano. Hungry for some science, but you don’t have time for a full-course research plate? Then check out USGS Science Snippets, our snack-sized science series that focuses on the fun, weird, and fascinating stories of USGS science.The products of volcanism that build volcanoes and leave lasting marks on the landscape include lava flows that vary in viscosity and gas content, and tephra ranging in size from less than a mm to blocks with masses of many tonnes. Next EarthWord: Our next word sounds like what the British might call an outhouse. In determining what types of oil and gas are present, as well as how much is technically recoverable, viscosity of the petroleum is very important. Finally, viscosity is also a factor in our oil and gas research.Next, in our water studies, the viscosity of both surface water and groundwater can affect all manner of things, from how fast a river flows to how deep groundwater can percolate. ![]() First, when studying the flow of lava and its effects, the viscosity of the flow can affect the speed at which the lava travels. Viscosity factors into USGS science in a number of ways.It affects how these liquids behave, and can change depending on such factors as temperature and pressure. Viscosity is an important measurement in most studies of fluids, from water to oil.Use/Significance in the Earth Science Community: ![]() Speaking of molasses, viscosity comes from the Latin viscosus, which meant “sticky.”.Ever heard the phrase “slower than molasses?” Viscosity is what it’s referring to, since molasses has a fairly high viscosity and so doesn’t flow very quickly. Viscosity refers to a fluid’s resistance to flowing.As the lava cools on the surface, its viscosity increases and the flow slows down. A USGS geologist collects a molten lava sample during a December 2015 lava flow from Puʻu ʻŌʻō. ![]()
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