A Look Into Volcanoes
I. Introduction Volcano: defined is a mountain or hill formed by the accumulation of materials erupted through one or more openings (called volcanic vents) in the earth's surface. The term volcano can also refer to the vents themselves. Most volcanoes have steep sides, but some can be gently sloping mountains or even flat tablelands, plateaus, or plains. The volcanoes above sea level are the best known, but the vast majority of the world's volcanoes lie beneath the sea, formed along the global oceanic ridge systems that crisscross the deep ocean floor. According to the Smithsonian Institution, 1511 above-sea volcanoes have been active during the past 10,000 years, 539 of them erupting one or more times during written history. On average, 50 to 60 above-sea volcanoes worldwide are active in any given year; about half of these are continuations of eruptions from previous years, and the rest are new. Mount St. Helen Volcanic eruptions in populated regions are a significant threat to people, property, and agriculture. The danger is mostly from fast-moving, hot flows of explosively erupted materials, falling ash, and highly destructive lava flows and volcanic debris flows. In addition, explosive eruptions, even from volcanoes in unpopulated regions, can eject ash high into the atmosphere, creating drifting volcanic ash clouds that pose a serious hazard to airplanes. II. Volcano Formation All volcanoes are formed by the accumulation of magma which is molten rock that forms below the earth's surface. Magma can erupt through one or more volcanic vents, which can be a single opening, a cluster of openings, or a long crack, called a fissure vent. It forms deep within the earth, generally within the upper part of the mantle which is one of the layers of the earth's crust, or less commonly, within the base of the earth's crust. High temperatures and pressures are needed to form magma. The solid mantle or crustal rock must be melted under conditions typically reached at depths of 50 to 60 mi. (80 to 100 km) below the earth's surface. Once tiny droplets of magma are formed, they begin to rise because the magma is less dense than the solid rock surrounding it. The processes that cause the magma to rise are poorly understood, but it generally moves upward toward lower pressure regions, squeezing into spaces between minerals within the soli...
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...the first blobs of melt. As melting continues other minerals start to melt as well, and the chemistry of the magma changes. From studies like this geologists have determined that the early stages of a Hawaiian volcano's life is generated by magmas derived from only small degrees of partial melting (such as only 5% of the source melting and the rest staying behind). On the other hand, when the volcano really gets going (such as at Kilauea and Mauna Loa), the percentage of source rock that melts to produce the magma is perhaps as high as 20%. There are many other ways in which chemistry is used in volcanology, including the studies of volcanic gases, crater lakes, and trying to determine the temperatures that lava had at the time they were erupted even long after the eruption has ended.
Bibliography
Bibliography 1999 Microsoft Encarta; Volcanoes 1980 USGS; www.vulcan.wr.usgs.gov 2000 Volcano World; http://volcano.und.nodak.edu/vwdocs/frequent-questions/grp13/question1544.html 1980-2000 USGS; www.vulcan.wr.usgs.gov/photo/volcanoes/MSH/framework.html 1993-2000 Microsoft Corporation; various volcano media 2000 FEMA; www.fema.gov/library/volcanof.htm
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Over the centuries, the making of the Big Island as we know it today eventually entailed the growth and conjoining of six separate volcanoes, building all the way up from the seafloor, some 18,000 feet below the ocean’s surface. These volcanoes, from northwest to southeast, are named Mahukona, Kohala, Mauna Kea, Hualalai, Mauna Loa and Kilauea, and become younger as one moves north to south. Mahukona Volcano, just off the Big Island’s northwest coast, was the first volcano to start forming. Now submerged beneath the surface of the ocean because it is sinking into the Earth’s crust under its own vast weight, Mahukona is no longer visible. As the Pacific Plate slowly continued moving northwestward over the hotspot, the location of the rising magma moved relatively southeastward, and through time the rest of the Big Island volcanoes formed along that path.After Mahukona, Kohala Volcano, the precursor to today’s Kohala Mountain, erupted next. As Kohala Volcano emerged from the sea and joined with Mahukona, a much larger Big
Mauna Loa is the largest volcano in the world measuring 2,000 miles². Mauna Loa is 13,677 feet tall, 74 miles long, and 64 wide. On March 24, 1984, at 1:30 in the morning, Mauna Loa began to erupt. This eruption is known as a quiet eruption. The eruption does not cause the volcano to explode or make much of a loud noise. This is due to the basaltic lava and a low amount trapped gases. It just flows a low viscosity lava out of the volcano. When the eruption started, lava started pooling out of the top of Mauna Loa. Within 2-3 hours about 80% of the crater on top of the volcano was submerged in lava. Many worried that the lava would overflow and run to the Mauna Loa Observatory, but the eruption shifted to go northeast rift zone instead. This instead threatened the nearby city of Hilo, populating 40,000 people. The lava headed straight for the town. On the way, the lava reached a generator and left it destroyed. This took out the power for the observatory on the other side of the volcano. This lava that Mauna Loa erupted is a basaltic lava. Basaltic lava silica content is low and only contains 45-55% silica. This makes the magma more liquid and gives it the ability to move quickly. As the lava approaches the vulnerable city of Hilo, many of the people began evacuating. Luckily, the lava stopped at the outskirts of town, burying 16 miles of land owned by the state, never to be seen again. The
Volcanoes are one of the most disastrous yet captivating geological land forms on earth. Many volcanic eruptions are catastrophic, but not all volcanic eruptions are as brutal. The two case studies I have chosen to compare and contrast are the 1980 Mount St. Helens eruption with the eruption of Hawaii’s Kilauea volcano which is still active today.
Volcanoes have played a key role in forming the face of the earth as we know it today. Some of the most well known landmarks and locations in the world are volcanoes. From the Hawaiian Islands to Mount Vesuvius, the Earth is populated with hundreds of active and dormant volcanoes. Among these volcanoes there are multiple different types. Stratovolcanoes, the most dangerous type of volcanoes, are built by multiple eruptions over many years. Shield Volcanoes, the largest recognizable volcanoes, are characterized by being short but very broad with low sloping sides. Cinder cones, the most common type of volcano in the world, are composed of large amounts of tephra, or pyroclastic debris. The last type of volcano is supervolcanoes. Supervolcanoes are the largest volcanoes. They also have the highest potential for damage. This paper will discuss these these different types of volcano.
Kilauea is the youngest volcano on the Big Island of Hawaii. Still active, there have been 34 eruptions since 1983. Kilauea is a shield volcano, meaning it covers a wide range of area, and has sloping sides. Kilauea is usually confused as being a smaller part to the neighboring Mauna Loa volcano, but it has it’s own lava flow system which makes it special to the Hawaiian islands. The history of eruptions from Kilauea is lengthy and the volcano’s name actually means, “spewing.” The oldest documented samples of lava date back almost 3,000 years and the oldest human documented eruption happened in 1823.
Earth has physically changed millions of times due to moving tectonic plates which has formed our planets mountains; altering the way our environment looks. Volcanoes, (formed when magma from the upper mantle heads to the surface, causing the land to rise) are one of nature’s finest spectacles. These geographical forces have erupted many times; from small-scale eruptions to cataclysmic ones; making them a force to consider about. Therefore the past is useful in predicting possible future eruptions as in terms of the effects they can have on civilisation, they are unpredictable in what they can produce.
Moore, R. B. (1992). "Volcanic Geology and Eruption Frequency, Lower East Rift Zone of Kilauea Volcano, Hawaii." Bulletin of Volcanology, 54(6), 475-483.
Digging up the dirt on Mauna Loa. (Hawaiian volcano studied) Science News v144, n25-26 December 18th, 1993 414 (1 page)
Volcanoes have always been a mysterious wonder of the world. Volcanoes have shaped the landscape and the very ground that we all live on. People have written stories of their disastrous eruptions, and painted their marvelous shapes on canvas. The essay will outline some of the more famous volcanoes and how they have impacted are history. Mount Vesuvius that destroy the great city of Pompeii, Krakatoa they spewed deadly ash on small village town, and Mount St. Helen, the only volcano in my own country to every erupt during my own time period.
Stories about volcanoes are captivating. Myths come in different versions, but all of them are capable of capturing yours, and everybody’s imagination.
Volcanoes are one of natures most interesting and dangerous phenomenons. The way volcanoes operate can be understood, on a basic level, by just some simple physics and chemistry, this paper will investigate and explain some of the basic physics that govern the behavior of volcanoes.
Numerous methods are available for monitoring volcanic activity, and scientists typically synthesize data and observations from all methods available in order to obtain the most comprehensive look at the area being observed. One frequently used technique is monitoring seismic activity that may indicate flow of magma and gas beneath the surface. As magma at extreme temperatures of sometimes over one thousand
Volcanoes can be one of the most destructive forces on Earth. It is estimated that some
The earliest outcropping volcanic deposits date back to about 25,000 years ago. The lavas observed at a -1125 m bore-hole are about 0,3-0,5 million years old. It is known for the first eruption of which an eyewitness account is preserved, in 79 AD. Geologically, Vesuvio is unique for its unusual versatility. Its activity ranging from Hawaiian-style release of liquid lava, fountaining and lava lakes, over Strombolian and Vulcanian activity to violently explosive, plinian events that produce pyroclastic flows and surges.