Volcanoes, according to Ball (para, 1), are very important to human beings living around them. They provide them with fertile soils, essential minerals, water reservoirs, natural beauty and geothermal resources. However, volcanoes can sometimes be very dangerous. The major questions that people living around volcanoes ask themselves are where they should go incase the volcano erupts and what the volcano hazards that face them are. In the United States, as illustrated by the U.S. Geological Survey (para, 1), almost 50 volcanoes have erupted one or several times in the last 200 years. Alaska, California, Hawaii, Oregon, and Washington (U.S. Geological Survey para, 1) are the most volcanically active regions in the U.S. There are different types of volcanic eruptions which result in different types of hazards, making it difficult to come up with an answer for the types of volcanic hazards that people living around volcanoes face. The U.S. Geological Survey (para, 2), states that volcanoes produce a wide range of volcanic hazards that results in death of many people and animals in addition to destruction of property.
Eruptions endanger the lives of people thousands of miles away from the volcanic site. They also have devastating impacts on the climate. Though extensive research has been done for decades, scientists have not yet discovered all about volcanoes. They are natural systems which have some feature of unpredictability. Volcanologists focus their work on understanding the behavior of volcanic hazards and ways of preventing them. Different types of volcanic hazards include volcanic earthquakes, Eruption Columns and Clouds Tehra, lava flows, pyroclastic density currents, pyroclastic falls, volcanic gases, landslides tsunamis, and lahars (Kreger para, 2).
Kreger (para, 4) states that during a volcanic eruption molten and solid rock fragments as well as volcanic gases are blasted into the air with great force. The biggest fragments of these rocks usually fall back to the ground within a distance of approximately two miles of the vent. Small fragments of volcanic eruption rise far above the ground into the atmosphere and form a big bulging eruption column. These columns can expand reaching more that 12 miles above the volcano within a period of less than 30 minutes forming an eruption cloud (Kreger para, 5). Volcanic ashes in the air pose a serious danger to aeroplanes. Big eruption clouds can be swept miles and miles away from the eruption site by wind leading to an ash fall. Heavy ash fall leads to destruction of buildings while minor ash fall leads to destruction of crops, machinery, and electronics. Mount St. Helens, Washington, eruption is one of the best examples which led to eruption columns that fell over a wide area in the western United States (U.S. Geological Survey Para, 3).
Volcanoes usually release gases during eruption. Sometimes, even though the volcano may not be erupting, cracks on the volcano may allow gases to escape to the air. Most of the gases released by volcanoes are steam (U.S. Geological Survey para, 4). Other common volcanic gases include Sulfur dioxide, carbon dioxide, hydrogen, hydrogen sulphide, and fluorine. Sulfur dioxide gas reacts with water droplets in the atmosphere leading to creation of acid rain. Acid rain, as illustrated by Pacific Disaster Center (para, 9), brings about corrosion and destruction of vegetation. Carbon dioxide, which is heavier than oxygen, is trapped in low areas in high concentration leading to death of both animals and people. Fluorine in high concentrations is very toxic to both animals and human beings.
Lava flows the other forms of volcanic hazards are molten rocks pouring onto the surface of the earth (Ball para, 3). The rate of flow of lava, according to (Ball para, 3), is determined by the concentration of silicon dioxide in them and the gradient of the volcano slope. Lava containing low silicon dioxide can form rapid moving streams of vast broad thin sheets. Higher silica concentrated lava tend to be thick and sluggish and travel very short distances. Pyroclastic flows are high speed floods of hot ash, molten rock bits, and gas which move down the sides of a volcano during eruptions or when the sloppy side of an expanding lava dome breaks apart. Pyroclastic flows are very hot up to about 15,000 F and move with a speed of about 150 miles per hour (Ball para, 4). Pyroclastic flows follow valleys and other depressions destroying everything they find on their paths. The high temperatures can set structures ablaze after engulfing them. Pyroclastic surges are pyroclastic flows of lower density formed when magma interacts with water explosively, and are able to overflow ridges hundreds of feet above the ground (Pacific Disaster Center para, 7). Mt. St Helens eruption in 1980 is a good example of volcanic activity that led to generation of a series of explosions that formed a big pyroclastic surge (U.S. Geological Survey para, 10).
Pyroclastic falls, also referred to as volcanic fallout, occur when broken rocks are expelled from a volcanic vent at high pressure during an eruption falling on the ground only a short distance from the vent. Falls are associated with plinian eruptive columns, volcanic plumes, and ash clouds. Pyroclastic materials released into the atmosphere have very devastating effects. These materials can be spread far and wide by wind resulting in blockage of sunlight leading to temporary cooling of the earths surface (Kreger para, 12).
The other types of volcano hazards are volcano landslides. Debris storms and landslides are fast downhill movements of rocky molten material. They range in size from small downhill movements of loose fragments on the surface of the earth to extensive collapses of the whole sides of a volcano. Sloppy volcanoes are vulnerable to landslides due to the fact that they are made up of layers of loose fragments of volcanic rocks. Hot debris also turns rocks on volcano surface into soft slippery clay (Pacific Disaster Center para, 8). Occurrence of landslides on volcano slopes is aggravated when heavy rainfall, eruptions, and huge earthquakes cause fragments to break loose and flow down hill. More than five landslides as noted by the U.S. Geological Survey (para, 17) have swept down the slopes of Mt. Rainer over the last 6,000 years.
Lahars are flows made up of mud and debris mostly containing volcanic materials on the edges of a volcano. Flows of mud, rocks, as well as water have the ability of rushing down valleys and streams at the speed of about 40 miles per hour and can reach distances of more than 50 miles. Some lahars may have so much rocks and debris that they appear as if they are high-speed flowing rivers of wet concrete. Lahars, according to Pacific Disaster Center (para, 10) are so powerful that they can easily uproot and carry trees, houses, cars, and big boulders for long distances downstream. They burry everything they find on their paths with mud. Lahars in history have been one of the deadliest volcano hazards. Although they occur mostly during an eruption they can also occur when the volcano is calm. Intense rainfall, breakout of a peak Crater Lake, melting snow and ice are the sources pf water that creates lahars. Lahars are a great danger to people and animals living downstream from glacier-clad volcanoes, an example being Mt. Rainer (U.S. Geological Survey para, 21).
Eruptions endanger the lives of people thousands of miles away from the volcanic site. They also have devastating impacts on the climate. Though extensive research has been done for decades, scientists have not yet discovered all about volcanoes. They are natural systems which have some feature of unpredictability. Volcanologists focus their work on understanding the behavior of volcanic hazards and ways of preventing them. Different types of volcanic hazards include volcanic earthquakes, Eruption Columns and Clouds Tehra, lava flows, pyroclastic density currents, pyroclastic falls, volcanic gases, landslides tsunamis, and lahars (Kreger para, 2).
Kreger (para, 4) states that during a volcanic eruption molten and solid rock fragments as well as volcanic gases are blasted into the air with great force. The biggest fragments of these rocks usually fall back to the ground within a distance of approximately two miles of the vent. Small fragments of volcanic eruption rise far above the ground into the atmosphere and form a big bulging eruption column. These columns can expand reaching more that 12 miles above the volcano within a period of less than 30 minutes forming an eruption cloud (Kreger para, 5). Volcanic ashes in the air pose a serious danger to aeroplanes. Big eruption clouds can be swept miles and miles away from the eruption site by wind leading to an ash fall. Heavy ash fall leads to destruction of buildings while minor ash fall leads to destruction of crops, machinery, and electronics. Mount St. Helens, Washington, eruption is one of the best examples which led to eruption columns that fell over a wide area in the western United States (U.S. Geological Survey Para, 3).
Volcanoes usually release gases during eruption. Sometimes, even though the volcano may not be erupting, cracks on the volcano may allow gases to escape to the air. Most of the gases released by volcanoes are steam (U.S. Geological Survey para, 4). Other common volcanic gases include Sulfur dioxide, carbon dioxide, hydrogen, hydrogen sulphide, and fluorine. Sulfur dioxide gas reacts with water droplets in the atmosphere leading to creation of acid rain. Acid rain, as illustrated by Pacific Disaster Center (para, 9), brings about corrosion and destruction of vegetation. Carbon dioxide, which is heavier than oxygen, is trapped in low areas in high concentration leading to death of both animals and people. Fluorine in high concentrations is very toxic to both animals and human beings.
Lava flows the other forms of volcanic hazards are molten rocks pouring onto the surface of the earth (Ball para, 3). The rate of flow of lava, according to (Ball para, 3), is determined by the concentration of silicon dioxide in them and the gradient of the volcano slope. Lava containing low silicon dioxide can form rapid moving streams of vast broad thin sheets. Higher silica concentrated lava tend to be thick and sluggish and travel very short distances. Pyroclastic flows are high speed floods of hot ash, molten rock bits, and gas which move down the sides of a volcano during eruptions or when the sloppy side of an expanding lava dome breaks apart. Pyroclastic flows are very hot up to about 15,000 F and move with a speed of about 150 miles per hour (Ball para, 4). Pyroclastic flows follow valleys and other depressions destroying everything they find on their paths. The high temperatures can set structures ablaze after engulfing them. Pyroclastic surges are pyroclastic flows of lower density formed when magma interacts with water explosively, and are able to overflow ridges hundreds of feet above the ground (Pacific Disaster Center para, 7). Mt. St Helens eruption in 1980 is a good example of volcanic activity that led to generation of a series of explosions that formed a big pyroclastic surge (U.S. Geological Survey para, 10).
Pyroclastic falls, also referred to as volcanic fallout, occur when broken rocks are expelled from a volcanic vent at high pressure during an eruption falling on the ground only a short distance from the vent. Falls are associated with plinian eruptive columns, volcanic plumes, and ash clouds. Pyroclastic materials released into the atmosphere have very devastating effects. These materials can be spread far and wide by wind resulting in blockage of sunlight leading to temporary cooling of the earths surface (Kreger para, 12).
The other types of volcano hazards are volcano landslides. Debris storms and landslides are fast downhill movements of rocky molten material. They range in size from small downhill movements of loose fragments on the surface of the earth to extensive collapses of the whole sides of a volcano. Sloppy volcanoes are vulnerable to landslides due to the fact that they are made up of layers of loose fragments of volcanic rocks. Hot debris also turns rocks on volcano surface into soft slippery clay (Pacific Disaster Center para, 8). Occurrence of landslides on volcano slopes is aggravated when heavy rainfall, eruptions, and huge earthquakes cause fragments to break loose and flow down hill. More than five landslides as noted by the U.S. Geological Survey (para, 17) have swept down the slopes of Mt. Rainer over the last 6,000 years.
Lahars are flows made up of mud and debris mostly containing volcanic materials on the edges of a volcano. Flows of mud, rocks, as well as water have the ability of rushing down valleys and streams at the speed of about 40 miles per hour and can reach distances of more than 50 miles. Some lahars may have so much rocks and debris that they appear as if they are high-speed flowing rivers of wet concrete. Lahars, according to Pacific Disaster Center (para, 10) are so powerful that they can easily uproot and carry trees, houses, cars, and big boulders for long distances downstream. They burry everything they find on their paths with mud. Lahars in history have been one of the deadliest volcano hazards. Although they occur mostly during an eruption they can also occur when the volcano is calm. Intense rainfall, breakout of a peak Crater Lake, melting snow and ice are the sources pf water that creates lahars. Lahars are a great danger to people and animals living downstream from glacier-clad volcanoes, an example being Mt. Rainer (U.S. Geological Survey para, 21).
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