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From: Marilou Hawkins
Date: 10/11/02
Time: 10:29:10 PM
Remote Name: 207.65.228.216
Here is the proposed draft of the final report for this week. Please look it over and provide feed-back. Event: Mount Pinatubo is a volcano located on the Philippine Island of Luzon, approximately 80 miles northwest of Manila. It erupted violently from June 12-15. Although it lay dormant for more than 500 hundred years, geologists recognized some signs a few months before the eruptions. The full blow of Mount Pinatubo, the second largest volcanic eruption of the twentieth century, was quite unexpected. Over 50,000 people were forced to evacuate and two major military bases were closed. Several hundred lives were lost as a result of the Mount Pinatubo eruption. (http://earthobservatory.nasa.gov/Study/AstronautPinatubo) The eruption began, April 2, 1991, with the ejection of small amounts of ash, which was followed three days later by high frequency volcanic quakes, indicating fracturing of rocks and movement of fault structures from pressure exerted by intruding magma and escaping steam. June 7, 1991, incidents of HFVQ’s increased from 26-178 daily to 1500-2000 daily, and low frequency quakes began, indicating that magma was nearing the surface. Harmonic tremors, indicating intensified seismic activity, began then and continued through the next day when scientists recorded an explosion type earthquake around 3:35 PM. June 9 (Day 1) the eruption began with eight hours of ash-laden steam clouds being ejected, followed by pyroclastic flows that flowed into the Maraunot and Moraza rivers; intermittent occurrences of small pyroclastic flows persisted all morning. On Day 4, three major explosions, the most powerful of which, ejected a cloud of ash that reached 20 kilometers above the vent, followed intense seismic activity. Ash pumice, and other large volcanic fragments were also ejected. Shortly before midnight a second series of explosions hurled clouds of ash and pyroclastic materials 25 kilometers into the air. Day 5, eruptions triggered heavy ash falls that blanketed most of Zambales, Tarlac, and Pampanga. Day 6, two major eruptions sent a column of debris to a maximum height of 30 kilometers, and pyroclastic flows 15 kilometers from the source. Day 7, eruptions produced a 40-kilometer high column and pyroclastic flows that advanced 16 kilometers from the center of activity. From 11:17 AM to 1:42 PM eruptions came in such close succession that they appeared to be one continuous activity. (http://hannover.park.org/Philippines/pinatubo) Pinatubo’s height before the eruption was 1,745 meters, and 1,485 meters at the highest point of the caldera’s rim after the eruption. The eruption disgorged a cubic mile of volcanic debris, and vented 18.14 million metric tons of sulfur dioxide into the atmosphere, that, after reaching the stratosphere, circled the earth in three weeks. This was the largest sulfur dioxide cloud ever detected to date by satellite. (http://www.emporia.edu/earthsci/student/sneed3/pinatubo.htm)
Lithosphere:
The earth is divided into three different chemical layers: the core, composed mostly of iron and nickel, remains very hot after 4,5 billion years of cooling; the mantle (the middle layer), is rich in the elements iron, magnesium, silicon and oxygen; and the crust which is rich in the elements oxygen and silicon with lesser amounts of aluminum, iron, magnesium, calcium, potassium, and sodium. There are two types of crust: dense oceanic crust made of basalt, and continental crust made of lower density rock such as andesite and granite. The outermost layers of Earth can be divided by their physical properties into the lithosphere and athenosphere. The lithosphere is the rigid outer layer made of crust and uppermost mantle. It is the ‘plate’ in plate tectonic theory. The mantle supports seven large plates and over 20 smaller plates of the lithospheric crust. These plates, because they sit atop the more fluid mantle (the athenosphere), are moving at a rate of a few inches per year. Sometimes these plates collide or are forced apart. When this occurs, the crust is weakened and when magma escapes from these open areas, new material is added to existing plates. The athenosphere is the part of the mantle that flows, that is, exhibits “plastic behavior” much like toothpaste in a tube. The flow of the athenosphere is part of mantle convection, which plays a major part in moving the lithospheric plates. (http://volcano.und.nodak.edu/vwdocs/vwlessons/plate_tectonics/pla…) The lithosphere is the rigid inorganic portion of the Earth, which contains the crust, and 80 to 100 km of the mantle. Thickness of the lithosphere averages about 100km, however, the lithosphere can be just a few miles under the oceans and up to 300 km beneath the continents. (http://visearth.ucsd.edu/) The lithosphere includes the uppermost mantle, the rocks of seabed crust, the rocks of continental crust and their attendant soils. The rocks of the lithosphere are of three types: igneous (basalt, granite,), metamorphic (marble, slate), and sedimentary (limestone, sandstone). Soils are designated by particle size (gravel, sand, clay and silt), and by detailed descriptions of their color and the conditions that form them (ultisols, entisols, spodisols, etc). (Goode’s Atlas 19th Ed. P. 20) The lithosphere includes all the geologic forms on the Earth’s surface: sea floors, trenches, islands, plains, plateaus and mesas, valleys and basins, hills, mountains, and volcanoes, and all their parts. ("http://encarta.msn.com/encnet/refpages/refarticle.aspc?refid=7615") A volcano is a vent or opening in the earth’s crust through which magma, molten rock, crystals, and dissolved gases, from the upper mantle and lower crust erupts as lava; it is also the landform that is produce by the erupted material. As magma is formed, it begins to rise toward lower pressure regions. Before erupting, it tends to accumulate in magma reservoirs, or underground storage regions. Materials such as lava, tephra, or rock fragments, and gases are released from volcanic eruptions. Each eruption adds layers to the volcano. (http://encarta.msn.com/encnet/refpages/refarticle.aspc?refid=7615) There are three major types of volcanoes: Cinder cone, shield, and the composite or stratovolcano. The simplest type of volcano is the cinder cone. It is built from particles and blobs of congealed lava ejected from a single vent. As gas-charged lava is blown violently into the air, it breaks up into small fragments that solidify and fall as cinders or scoria around the vent to form a circular or oval cone. Most cinder cones have a bowl-shaped crater at the summit and rarely rise more than one thousand feet above their surroundings. Scoria forms when blobs of gas charged lava thrown into the air cool in flight and fall as dark volcanic rock containing cavities created by trapped gas bubbles. (http://vulcan.wr.usgs.gov/Glossary/CinderCone/description_cinder…) Shield volcanoes are built almost entirely of fluid lava flows. Flow after flow pours out in all directions from a central summit vent, or group of vents, building a broad gently sloping cone with a shape similar to a warrior’s shield. Lavas also commonly erupt from vents along fractures that develop on the flanks of the cone. Some of the largest volcanoes in the world are shield volcanoes (Kilauea, Mauna Loa). (http://Vulcan.wr.usgs.gov/Glossary?ShieldVolcano/description_shield …) Some of the earth’s grandest mountains are composite volcanoes, also called stratovolcanoes. Typically steep-sided cones, they are built of alternating layers of lava flows, volcanic ash, cinders, blocks, and bombs and may rise 8,000 feet above their bases. Most composite volcanoes have a crater at the summit, which contains a central vent or group of vents. Lavas either flow through breaks in the crater wall or issue from fissures on the flanks of the cone. Lava, solidified within the fissures, forms dikes that act as ribs which greatly strengthen the cone. The essential feature of a composite volcano is a conduit system through which magma from a reservoir deep in the earth’s crust rises to the surface. The volcano is built up the accumulation of material erupted through the conduit and increases in size as lava, cinders, ash, etc. are added to its slopes. Composite volcanoes tend to erupt explosively and pose a great danger to nearby life and property. Composite cones like Mount St. Helens and Mount Pinatubo are frequently found along subduction zones where one plate is being pushed under the edge of another plate. (http://Vulcan.wr.usgs.gov/Glossary?StratoVolcano/description_com…)
L>E: It is the activities of the lithosphere that produced Pinatubo. Because the Philippine plate is being pushed under the Asian plate the Philippine Islands and their stratovolcanoes are created by the subduction zone created this tectonic plate movement. The sinking of the oceanic plate into the athenosphere generates magma under the continental crust. As the magma builds it rises through the weakest portions of the crust to form volcanoes. Because the magma in subduction zones is very thick its and gases are released explosively, most of the volcanoes in these subductive zones are composite or stratovolcanoes, produced by repeated, explosive eruptions. (http://volcano.und.nodak.edu/vwdocs/vwlessons/plate_tectonics/pla…)
E>L: The three main destructive agents were: ash fall, pyroclastic flow, and lahars (mudflows). Initially the ash tends to smother everything, but in the long term in acts a rich fertilizer for many crops. Pyroclastic flows (superheated mixtures of gases, volcanic fragments, ash pumice, crystals and glass shards), with their intense, penetrating heat, and enormous speeds, destroyed everything in their path. Lava floods created long-lasting damage down slope. Mount Pinatubo emitted around 8-10 km of material onto the surrounding slopes. The total elevation of the top of the mountain was lowered by around 150m. Forests and rice fields were destroyed by the eruption. Hundreds of cubic meters of loose sand and gravel fell on the upper slopes of the mountain. The event also created post-eruption mudflows, or lahars. Lahars reshape the landscape, forcing the formation of new river channels, damming new lakes, and polluting waters far from the center of eruption and for months and years after the event. (http://earthobservatory.nasa.gov/Study/AstronautPinatubo)
Atmosphere: The atmosphere is the gaseous area surrounding the Earth, divided into 5 areas: troposphere, stratosphere, mesosphere, thermosphere, and exosphere. The Troposphere is the atmospheric layer closest to Earth and contains the largest percentage of the mass of total atmosphere. The troposphere contains 99% of the water vapor in the atmosphere. All weather phenomena occur within the troposphere, but some turbulence may extend into the stratosphere, the next layer in the atmosphere. Approximately 90% of the ozone in the atmosphere resides in the stratosphere. The ozone( a particularly reactive form of oxygen which is formed when oxygen is produced: (http://csep10.phys.utk.edu/astr161/lect/earth/atmosphere.html) absorbs the bulk of the solar ultraviolet radiation in the atmosphere due to it’s closeness to the Sun. (http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/ATM_CHEM/atmospheric_structure.html) The troposphere and stratosphere are the two layers that we will concentrate our sphere study on. E>A: The eruption of Mt. Pinatubo was one of the largest and it strongly affected some aspects of our climate. This eruption helped to produce the largest sulfur oxide cloud this century. Part of this aerosol plume that Mt. Pinatubo left diffused around the globe in a matter of months. The data collected after this eruption showed that the mean world temperatures decreased by about 1 degree Centigrade over the subsequent two years. (http://www.geology.sdsu.edu/how_volcanoes_work/climate_effects.html ) This caused a cooling effect of the Earth. Many scientists who saw it as a counter-balance to global warming welcomed this effect of the eruption. The volcanic eruption of Mt. Pinatubo caused a dense thick “fog” or layer of gas in the atmosphere that caused low or no visibility in the surrounding areas of the eruption. The volcano erupted with such an intensely combustible force that volcanic ash, lava, and volcanic gases, {such as sulfur dioxide}, were spewed up and out for miles and miles into the atmosphere and onto the Earth making visibility very low or non-existent. (http://library.thinkquest.org/ ) We have dense visibility in the atmosphere, sometimes on a daily basis, just not caused from a volcanic eruption, but a weather phenomenon called fog. When the atmosphere becomes saturated with moisture {saturation - when air contains as much water vapor as it can hold}; moisture becomes visible water droplets in the form of fog and clouds. The fog is the saturation of the atmosphere below 50ft of the troposphere and clouds from 50ft above the troposphere. (http://wings.avkids.com/Book/Atmosphere/instructor/clouds-01.html) The large and loud eruption of Mt. Pinatubo caused the atmosphere to be filled up with volcanic material, such as lava, rock, ash, and volcanic gases (sulfur dioxide), which almost completely consumed the oxygen that was in the atmosphere. The eruption allowed this volcanic material to “spew” out into the atmosphere. The violent ejection of the volcanic material came from the gaseous build up inside the Earth. This is much as when you shake up a can soda and open it; the force that is built up from the carbonation inside the soda causes the gas to expand suddenly, and that spews the drink everywhere (If you work with children, I am sure this is something common to your world, especially at snack time, Ha!). When the gases build up with nowhere for the gas to escape to the eruption is louder, larger, and produces more materials that is ejected from the volcano. (http://library.thinkquest.org/) However, some volcanic gases may not be carried away, but, instead, settle to the ground. In 1986, carbon dioxide released from the Lake Nylos, a volcanic crater in Cameroon, settled in a nearby low-lying area, asphyxiating at least 1700 villagers and animals. (http://www.cotf.edu/ete/modules/volcanoes/vhazards3.html) The volcano’s eruption can cause the atmospheric temperature to drop or cool dramatically. Gases and solids injected into the atmosphere cause a thick cloud of gas that blocks out the Sun for a period of time. When the Sun is blocked the Sun’s rays are not reaching the Earth’s surface to warm the atmosphere. Think of when you are working outside in the Sun at noontime. All of a sudden clouds began to roll in a what happens? When the clouds cover the Sun the temperature or the air seems to feel cooler. (http://.wings.avkids.com/Book/Atmosphere/instructor/clouds-01.html ) After the eruption of Mt. Pinatubo, in June of 1991, the sulfuric acid clouds encircled the Earth, resulting in higher levels of atmospheric sulfuric acid worldwide. The effect this had is that many of the Sun’s (heat energy and light) rays were absorbed, blocked, and /or reflected back into space. This caused a climatic forcing that cooled the northern hemisphere by 0.6 degree C. (http://www.emporia.edu/earthsci/student/sneed3/pinatubo.htm) The result was cooler temperatures worldwide. (NASA’s Earth Science Enterprise CD-ROM) The type of eruption can determine its effects on global cooling. Factors involved include the amount of gases released, the strength of the blast, the angle from which the aerosols are ejected, and the latitude of the erupting volcano. When the gases are emitted from the side of a volcano, the majority of the released sulfur dioxide stays in the troposphere and is not widely dispersed. However, gases ejected vertically out of the top of a volcano in an explosive blast are more likely to enter the stratosphere where they will be carried by the wind belts (i.e. the jet stream). Those wind belts, at high latitudes, tend to interact less with the wind belts elsewhere around the planet. However, there is a great amount of mixing of the wind belts at mid and low latitudes, so explosive volcanic eruptions there tend to have more of global effect on weather. (Welcome to NASA’s Earth Science Enterprise Activity Supplement). Mt. Pinatubo is at low latitude and its eruption had a major effect on global cooling. Not all large volcanic eruptions cause or contribute to global cooling. The eruption of El Chichon in southern Mexico, in 1982, seemed to have little global effect. However, scientists think this may be because El Nino (a Pacific Ocean weather phenomenon which causes worldwide weather variations) may have canceled out its effect. (NASA Fact Sheet: Volcanoes and Global Climate Change). However, gases ejected vertically out of the top of a volcano in an explosive blast are more likely to enter the stratosphere where they will be carried by the wind belts (i.e. the jet stream). Those wind belts, at high latitudes, tend to interact less with the wind belts elsewhere around the planet. The eruption of a volcano can send large amounts of volcanic material into the atmosphere suspending particles, such as dust and ash in the troposphere and stratosphere which can block the earth’s sunlight, thus reducing solar radiation and lowering global temperatures and causing a haze effect. The haze effect often generates exceptionally red sunsets due to the scattering of red wavelengths by sub micron-size particles in the stratosphere and upper troposphere that led to beautiful sunsets worldwide. (http://www.geology.sdsu.edu/how_volcanoes_work/climate_effects.html) A volcanic eruption can have a warming effect on the Earth. The water and carbon dioxide released by a volcanic eruption, in gaseous form, absorb the heat radiation emitted from the ground and hold it in the atmosphere causing the air below to get warmer. This is generally local and short term. However, it could have a greater effect if there were multiple major eruptions over long periods of time. (http://www.cotf.edu/ete/module/volcanoes/vclimate.html) While eruptions of this size have an immediate cooling effect, it appears that they contribute to global warming over time because of their venting of large amounts of carbon dioxide. The fact that their aerosols are so small and support water vapor longer in the atmosphere, producing high, thin clouds or haze, means that such eruptions produce just the conditions that make water vapor a greenhouse gas. (“Clouds and the Energy Cycle,” NASA Facts, p.2) The volcano’s eruption would cause a reduction in the oxygen that is in the atmosphere. The gaseous clouds, made mostly of sulfur dioxide, would rise into the atmosphere completely consuming or greatly depleting the oxygen that is in the atmosphere. (http://earthobservatory.nasa.gov/Study?Volcano/) The volcano’s eruption ejected volcanic material into the atmosphere causing further loss of the ozone ( a thin layer of a form of reactive oxygen). (http://library.thinkquest.org ). When the eruption happened volcanic gases, made mainly of sulfuric dioxide, spewed upward into the troposphere and stratosphere where they converted to aerosols of sulfate particles. These aerosols (small particles of liquid and solid matter suspended in air) are thought to contribute to ozone loss. The ozone is located in the upper stratosphere and when the cloud, from the volcanic eruption, formed and blocked the Earth from the Sun much of the sun’s heat energy and light rays were absorbed, blocked, or reflected back into space. The resulting cloud coverage encircled the Earth for two years, first in a narrow band, then dispersing outward. The ozone level over the polar region of the Southern Hemisphere reached the lowest recorded level. [NASA’s Earth Science Enterprise CD-ROM]. The sulfur dioxide emitted from a volcanic eruption can reach the stratosphere where it converts to sulfuric acid. (http://earthobservatory.nasa.gov/Study/Volcano/ ) These aerosols are attracted by chlorofluorocarbon (CFCs) in the stratosphere that in turn intensify the destruction of ozone molecules. (NASA’s Earth Science Enterprise Activity Supplement) (http://earthobservatory.nasa.gov/Study/Volcano/) A>E: The atmosphere is made up of many layers and our climate is directly related to these layers. (http://csep10.phys.utk.edu/astr161/lect/earth/atmosphere.html ) Winds caused from unstable atmospheric pressure, at the time of a volcanic eruption, could cause winds to spread the volcanic material even further than the combustion of the eruption. The winds, produced from the unstable air mass, could cause volcanic gases and clouds of dust and volcanic material to spread to all layers of the atmosphere thus blocking out the sun for hours. (http://library.thinkquest.org/17457/volcanoes/effects.pinatubo.php ) Millions of tons of ash may be carried by winds for hundreds or thousands of miles. (http://www.cotf.edu/ete/modules/volcanoes/vnarrative2.html)Winds, produced in the atmosphere, can increase or diminish the effect of an explosive volcanic eruption. If the ash is carried by the wind and then dropped into populated areas the effects on people, machinery, and crops can be intensified. (http://www.coft.edu/ete/modules/volcanoes/vnarrative3.html) If the unstable atmosphere produced rain at the time of the eruption, water droplets and sulfur dioxide, carbon dioxide, hydrogen sulfide and hydrogen would mix producing acid rain. (http://library.thinkquest.org/) (http://www.geology.sdsu.edu/how_volcanoes_work/climate_effects.html) The air in the atmosphere, can be cooled or heated from many weather changes, seasons, clouds, etc... (http://www.geology.sdsu.edu/how_volcanoes_work/climate_effects.html) and (http://www.wings.avkids.com/Book/Atmosphere/instructor/clouds-01.html) and with this cooling effect the air could, perhaps, cool the volcano, especially the lava, over a period of time. Hydrosphere: The hydrosphere is made up of the entire planet’s water. Water is the most widespread substance found in the environment. Water exists in three states: liquid, solid and invisible vapor. It forms the oceans, seas, rivers, and lakes. This also includes the underground waters found in the top layers of the Earth’s crust and soil cover. (www.dc.peachnet.edu/~pgore/geology/geo101/hydro.2.html). It is hard to assess the total water storage on the Earth water is in permanent. It is constantly changing from liquid to solid, to a gaseous state and back. It is estimated that 97.5% of the total water is salt water. 68.9% is made up of glaciers and permanent snow and 29.9% is fresh ground water. (http://webworld.unesco.org/water/ihp/publications/waterway/webpc./definition.html) E>H: Mt. Pinatubo affects Global Water Cycle. The presence of airborne materials from Mt. Pinatubo’s eruption affects the water cycle. These effects have been interpreted differently. Satellite observations initially showed a slight cooling, but later analysis implied warming. A warmer Earth speeds up the global water cycle (H): the exchange of water among the oceans, atmosphere and land. Higher temperatures cause more evaporation and soils tend to dry out faster. Increased amounts of water in the atmosphere will mean more rain or snow overall (H). (http://clinton2.nara.gov/Initiatives/Climate/last100.html) We (the U.S.) may be seeing the first signs of changes in the water cycle. Precipitation in the U.S. has increased about 6%, while the frequency of intense precipitation events (heavy downpours of more than two inches per day) has increased by 20%. Such events can cause flooding, soil erosion, and even loss of life. In some midcontinental areas, increased evaporation has led to drought because the heavy rains fell elsewhere. (http://clinton2.nara.gov/Initiatives/Climate/last100.html)
Volcanic eruptions can cause tsunamis. Tsunamis are large sea waves that have long wave periods. Volcanic earthquakes and explosions produce these waves. Tsunamis transmit energy to areas outside the reach of the volcanic eruption itself. With volcanoes, the most efficient method of tsunami formation includes a disruption of a body of water by the collapse of all or part of the volcano, and explosion, landslide, avalanche, or an earthquake. In other words, shock waves due to rapidly moving volcanic material and lahars or pyroclastic flows have entered the sea. Earthquakes may accompany the volcano before, during, or after the eruption. If a landslide occurs on the shores of an island, due to lava flows and lahars, the volcanic materials will flow into the surface of the ocean causing the water above to be thrown into an up and down motion creating a series of large waves, tsunamis. As the tsunamis approach the shore of a nearby island, or the Volcano Island for that matter all the energy stored in the deep waves transfers upward. The waves height increase and huge breakers come crashing onto the shore one after the other. (http://www.tsunami.org/faq.htm, http://www.ngdc.noaa.gov/seg/image/geohazards_v3/document/648001.htm, http://www/geo.mtu.edu/volcanoes/hazards/primer/sur.htm) It is suspected that very large volcanic eruptions may be associated with periods of glaciation on Earth. Research suggests that volcanic eruptions, coupled by cooling periods already in progress, may increase the effects of ice ages. (http://bigmac.civil.mtu.edu/home/classes/ce459/public/p14/climate.html) Volcanic gases are said to be the source of all the water (and most of the atmosphere) that we have today. The process of adding to the water and atmosphere is pretty slow, but if it had not been going on for the past 4.5 billion years or so we would be pretty miserable. Aerosols are tiny liquid and solid particles suspended in the air. These can come directly from volcanic eruptions. It is very difficult to form cloud droplets without small aerosol particles acting as “seeds” to start the formation of cloud droplets. According to theory, as aerosol concentration increases within a cloud, the water in the cloud gets spread over many more particles, each of which is correspondingly smaller. Smaller particles fall more slowly in the atmosphere and decrease the amount of rainfall. In this way, changing aerosols in the atmosphere can change the frequency of cloud occurrence, cloud, thickness, and therefore precipitation amounts. (http://eospso.gsfc.nasa.gov/ftp_docs/Aerosols.pdf) Another effect on weather right near a volcano is that there is often a lot of rain, lightning, and thunder during an eruption. This is because all the ash particles that are thrown up into the atmosphere are good at attracting/collecting water droplets. We do not quite know how the lightning is caused but it probably involves the particles moving through the air and separating positively and negatively and negatively charged particles. (http://volcano.und.nodak.edu/vwdocs/frequent_questions/top_101/oldEffectd.html) The eruption of volcanoes causes vog (volcanic fog) and leads to acid rain. Most gases released during eruptions of volcanoes consist of water vapor, which condenses as steam. Other gases such as carbon dioxide, sulfur dioxide, hydrogen sulfide and hydrochloric acid are also given off. Inside the volcano, when pressure is high, the SO2 is dissolved in molten rock or magma. When it rises toward the surface the SO2 escapes. (SO2 is a poisonous gas that irritates the skin and tissues and mucous membranes of the eyes, nose, and throat.) When sulfur dioxide is mixed with oxygen and water, or moisture, in the atmosphere it produces volcanic smog, called vog, and acid rain. Vog is a visible haze consisting of gas plus a mixture of tiny liquid and solid particles called aerosols. The aerosols in vog are composed of sulfuric acid and other sulfate compounds. Combined with the moisture in the atmosphere tiny sulfuric droplets are formed and fall as acid rain. Acid rain is a term coined by Robert Smith, a British chemist in 1872, to describe the nature of precipitation containing significant sulfuric acid. So the term describes precipitation including rain, sleet, hail, and snow that is acidic. According to James R. Craig, author of “Resource of the Earth,” it appears that natural phenomena such as volcanoes result in more sulfuric oxides in the atmosphere than human activities. (http://snrs.un1.edu/amet498/drake/effects.html http://geopubs.wr.usgs.gov/fact-sheets/fs169-97, http://davem2.cotf.edu/mtpe/courses/idaho/isphere/isvolcanoes/0029.html) Lahars (also called volcanic debris flows or mudflows) are mixtures of water-saturated rock debris that flow down slope under the force of gravity. Rocks within a volcano may be saturate, or water may be supplied by rainfall, by rapid melting of snow or ice, or by a debris-dammed lake or Crater Lake. Mudflows or debris flows are composed mostly of volcanic materials on the flanks of a volcano are called lahars. These flows of mud, rock, and water can rush down valleys and stream channels at speeds of 20 to 40 miles per hour and can travel more than 50 miles. Some lahars contain so much rock debris (60 to 90% by weight) that they look like fast-moving rivers of wet concrete. Close to their source, these flows are powerful enough to rip up and carry trees, houses, and huge boulders miles downstream. Farther downstream they entomb everything in their path in mud. (http://vulcan.wr.usgs.gov/Glossary/Hydrology/description_hydrologic_hazards.html) The melting of snow can produce floods related to volcanoes and ice during eruptions of ice-clad volcanoes, by heavy rains that may accompany eruptions and by transformation of lahars to stream flow. Floods carrying unusually large amounts of rock debris can leave thick deposits at and beyond the mouths of canyons and on valley floors leading away from volcanoes. Eruption-caused floods can occur suddenly and can be of large volume; if rivers are already high because of heavy rainfall or snowmelt, such floods can be far larger than normal. (http://vulcan.wr.usgs.gov/Glossary/Hydrology/description_hydrologic_hazards.html) In active volcanic areas, groundwater can affect intrusive and eruptive activity by influencing cooling rates, modifying the strength of rocks in the volcanic edifice, and converting thermal energy of magma to explosive mechanical energy. One of the greatest hazards posed by groundwater exists when it is heated by magma and violently released, as eruptions of either pure steam or steam mixed with fragmented magma or country rock. (http://vulcan.wr.usgs.gov/Projects/Mastin/framework.html) The dried lava from volcanoes can slow down or stop the flow of water resources in a particular area. H>E: Many of the Earth’s volcanoes are under the sea. The Earth’s crust under the oceans is relatively thin, about 3 miles, compared to the continental crust, which is between 20 and 40 miles thick. Magma is able to force its way up through the thin crust, particularly at plate edges. The hot molten lava explodes when it hits the cold seawater. The cold water cools the molten lava and thus islands can form. In November 1963, a fisherman saw a great column of smoke and ash rise from the sea southwest of Iceland. The next day a new island appeared and it continued to grow. An erupting volcano that was cooled off by seawater caused the volcano, which was named Surtsey. (Closer look at Volcanoes by Jen Green) H>E The eruption of a volcano can produce many interesting features, especially when cooled off by water. When lava flows into the ocean, it is quickly cooled into a shape known as pillow lava. (Volcanoes by Paul P. Sipiera) H>E Volcanic bombs can occur if water is present in lava during an eruption. A volcanic bomb is when fragments of rock are hurled into the air. This rock includes pieces of hard, solid rock that is ejected during an eruption. These volcanic bombs can travel for miles into nearby cities and towns. (Closer look at Volcanoes by Jen Green) H>E Rainfall after an eruption can cause numerous problems. The rainwater can mix with fallen ash to cause dangerous flows of mud. After the eruption of Mount Pinatubo, mudflows engulfed roads, bridges, and several villages. Not only was the eruption bad enough but also the rainfall caused even greater destruction. (Closer look at Volcanoes by Jen Green) Biosphere: The biosphere is made up of every living thing found on earth. All living organisms including animals, plants and microorganisms make up this sphere. Parts of the biosphere can be included in other spheres. For example, fish and aquatic plants can be found in our lakes, rivers, streams, and oceans. The biosphere is also known as the earth's thin zone of air, soil, and water. It is capable of supporting life. It ranges from about 6 miles into the atmosphere to the deepest ocean floor. Life that is in this zone depends on the sun's energy and on the heat and essential nutrients circulating about the earth. E>B: The most serious nearby environmental effect is the burial of either ash, mud, or lava. In many cases these materials bury the area under tens of meters. Anyone or anything caught by them would be killed. At Mt. Pinatubo the huge amount of ash deposited high on the slopes has caused way more damage to the lower areas than the original eruption did. Volcanoes effect people in many ways, some are good, some are not. For example, volcanoes affect people in a negative way when their houses, building, roads, and fields are covered by ash. The heavy amount of ash can cause houses to collapse. Therefore, people lose their homes due to the event. A positive way the volcanoes can help people is that it can produce very rich soils for farming. Therefore, the volcano helps farmers by providing food and income. The event of a volcano eruption can cause negative effects on livestock and other mammals. For example, lava flows, pyroclastic flows, tephra falls, atmospheric effects, gases and tsunami can kill livestock and other mammals. They can also die from famine, forest fires, and earthquakes caused by or related to the eruptions. Aquatic life can also be affected by the eruptions due to an increase in acidity, increased turbidity, change in temperature, and/or a change in food supply. These factors can damage or kill fish. Therefore, causing a problem in the food chain. Eruptions can also influence bird migration, roosting, flying ability, and feeding activity. Thus, causing a problem in the life cycle of a bird. The impact of eruptions on insects depends on the size of the eruption and the stage of growth of the insect. For example, ash is very abrasive to wings. The entire negative affects on the livestock and mammals could cause problems for humans as well. For example, the lack of livestock and mammals could put a damper on the food chain for humans. The fires that result from the eruptions could destroy all crops, vegetation and plant life in that area. Therefore, food supplies would be diminished. (http://pubs.usgs.gov./gip/volc/people.html) When a volcano erupts, it will literally kill any organism in its path. Dust and smoke will snuff out the air in immediate areas choking living organisms. Boiling hot liquid lava will disintegrate any being in its path. Secondary effects of a volcanic eruption on life forms would be that lava and dust would destroy habitats making it impossible for living things to survive even if they survive the initial eruption. (http://volcano.und.edu) Dust, smoke, ash, and debris from volcanic eruptions can cause severe secondhand effects on civilization. For example, dust from the eruption could cause different lung diseases and illnesses as well as different complications involving organisms with respiratory tracts. The different types of debris from the eruption could cause people and animals to have problems breathing, therefore, if it is not taken care of people and animals could parish. Mudflows can damage the biosphere in many ways. For instance, mudflows can occur when rain falls through clouds containing high levels of ash or when waters are dammed during an eruption. The flows could wipe out huge sections of crops, vegetation, plants, and animals. All of these sections are useful to humans in a variety of ways. Therefore, the food chain and life cycles of the biosphere would be affected. (http://volcano.und.edu) Volcanic eruptions have a negative effect on animals. For example, for the animals that do survive the eruption their food chain is affected. Their drinking water is contaminated from all the gases and debris. Therefore, any animal that drinks from the water source will die. The aquatic animals also suffer from this because of the acidity in the water. Volcanic eruptions also release toxic gases. Thus, they will have an affect on the entire biosphere. The cracks in the ground after an eruption enable gases to escape. Some of the gases that are released are carbon dioxide, sulfur dioxide, hydrogen sulfide, and hydrogen. The combining of water droplets and sulfur dioxide then produces acid rain. Thus, contaminating all water supplies for animals and people. Vast amounts of carbon dioxide can also be detrimental to people and animals. A positive effect of volcanic eruptions to plants is that the ash from the eruption can provide nutrients to the surrounding soil. The volcanic ash contains minerals that are very beneficial to plants. Therefore, the plants will be able to regenerate and thrive. B>E: People use volcanic products as construction materials. Some of these materials are used as cleaning agents and as raw materials for many chemical and industrial uses. The internal heat associated with some young volcanic systems has been harnessed to produce geothermal energy. The Isle of Surtsey didn't exist until 1963. A volcano under the sea erupted causing and island covering 2.4 Km to grow. The highest point is 170m above the sea. Geologists found that in only two years' time, the island was already inhabitant by many birds, insects, and plants. (http://www.oink.demon.co.uk/topics/vframes.htm) Intersphere relations: A>H: Changes in the atmosphere following the Mt. Pinatubo event could affect water resources. One such change includes increased temperatures. Evaporation is likely to increase with warmer climate. It could result in lower river flow and lower lake levels. If stream flow and lake levels drop, groundwater could also be reduced. (EPA-Climate Change-Office of Policy, Planning and Evaluation-September 1997) When a volcano erupts sulfur dioxide, ash particles are blasted into the air (Atmosphere). Once these things settle they can eventually end up in the water cycle. The water cycle is then polluted causing fish and other plant life to die. The ash and gases can pollute the water for years because they will continue to wash into the rivers and streams every time it rains because they will be carried through the run off process. Water bodies receive large amounts of volcanic ash and debris. Falling ash could cause a change in the pH of surface water. (http://Vulcan.wr.usgs.gov) H>B: Changes in water can affect the biosphere. All life depends on water to survive. With the water contaminated with ash and debris, the remaining animals will have little to drink. As a result, they may become dehydrated and eventually die if they cannot find a new source of water. Aquatic life can be affected by an increase in acidity, increased turbidity, change in temperature, and/or change in food supply. These factors can damage or kill fish. (http://volcano.und.nodak.edu/vwdocs/frequent_questions/top_101/oldEffects.html) L>H: Erosion from the volcano may be deposited in the water. The erosion deposits may change the chemical composition of the water, just as dumping pollutes the water. B>H: The death of plants and animals in the lakes and rivers causes an increase in organic material. This causes an increase in bacteria and further decreases 02 within the water. E>L>B: Lava floods and lahars create long-lasting damage down slope. Forests, grazing lands, and farm fields would be destroyed by volcanic eruptions. Crops and livestock would be killed, which could lead to starvation of people and animals that depend on them. ("http://earthobservatory.nasa.gov/Study/AstronautPinatubo") E>L>H>B: Fallen ash from the volcano smothers everything. This ash is heavily accumulated on the ground. After rainfall, the concrete-like mixture may collapse roofs and damage crops. ("http://encarta.msn.com/encnet/refpages/refarticle.aspc?refid=7615") E>L>H>B: A volcano is a result of shifting plates. These shifting plates of the lithosphere can cause the ocean floor to shift as well, resulting in tsunamis, large seismic sea waves. Tsunamis may be deadly to people who live in low-lying coastal areas. (http://encarta.msn.com/encnet/refpages/refarticle.aspc?refid=7615") E>A>L>H>B: It appears that the Pinatubo eruption may have influenced the hundred-year flood of the Mississippi River Valley that occurred in 1993, as well as the severe drought that occurred in the Sahel that same year. The cooling of the northern hemisphere, from the combination of aerosols and sulfur dioxide, seems to have produced unexpected rains in the mid-continent where there had been an over-all drying trend, and exacerbated the desertification of the Sahel. The exact relationship between the events is, however, difficult to trace with present technology and understanding. If the events are linked, it shows how intertwined are all of earth’s systems, and how great an impact any one event may ultimately have.(http://www.emporia.edu/earthsci/student/sneed3/pinatubo) Conclusions: Volcanism is part of earth’s recycling process. Crustal plates are being constantly created and destroyed. Where one plate slips under another subduction zones are created, and volcanoes like Pinatubo develop over these subduction zones. While the eruption of volcanoes can be enormously destructive, they are the most dramatic part of an ongoing land building process. Much of the ejecta of volcanoes are highly valued as a producer of rich agricultural soils. This is exhibited globally by the numbers of farms on the sides of volcanoes, both dormant and active, in spite of the inherent danger. Pinatubo’s eruption shows how dangerous volcanoes are, and how devastating the impact of so large an eruption can be to all spheres, over distances near and far. Volcanoes leave reminders that we are only human and there are some things that we cannot control, no matter how powerful we may be. By understanding the impact of large volcanic eruptions on the Earth’s climate system in more detail, perhaps scientists will be in a better position to suggest measures to lessen their effects on people, plants and animals, and on natural resources. 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Sipiera EPA-Climate Change-Office of Policy, Planning and Evaluation-September 1997