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From: Whitney Chenoweth
Date: 10/6/02
Time: 11:25:25 PM
Remote Name: 67.32.169.124
This includes information on the hydrosphere as well as S>S interactions.
Hydrosphere and Mt.Pinatubo
Background on volcanoes
The term refers to an opening in the earth’s surface through which molten rock gases are expelled. There are many volcanic eruptions; they include Hawaiian, Basaltic Flood, Strombolian, Vulcanian, Peleean, Plinian, Rhyolitic Flood, Ultravulcanian, Gas Eruptions, and Furmarolic. Volcanic fluids are called magma while within the volcano; once it reaches the surface its called lava. The word volcano comes from the little island of Vulcano in the Mediterranean Sea of Sicily.
Information related to the Mt. Pinatubo Event
On June 15, 1991, Mt. Pinatubo erupted. Mt. Pinatubo is a volcano north of Manila on the Philippine Island of Luzon. This was one of the largest volcanic eruptions in the 20th century. The eruption caused widespread destruction and loss of life. The Philippine Institute of Volcanology and Seismology and the US Geological Survey (USGS) forecasted the eruptions; evacuation saved thousands of lives. The eruption injured fewer than 500. http://earthsys.ag.ohio-state.edu/814/pinatubovolcano.htm
What is the 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)
Event and Hydrosphere Interactions
E>H Mt. Pinatubo affects Global Water Cycle. The presence of airborne materials from Mt. Pinatubo’s eruption affect 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
E>H We (the US) may be seeing the first signs of changes in the water cycle. Precipitation in the US 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
E>H The June 1991 eruption of Mount Pinatubo was global. Slightly cooler than usual temperatures recorded worldwide and the brilliant sunsets and sunrise have been attributed to this eruption set fine ash and gases high into the stratosphere, forming a large volcanic cloud that drifted around the world. The sulfur dioxide (SO20 in this cloud – about 22 million tons) combined with water to form droplets of sulfuric acid, blocking some of the sunlight from reaching the Earth and thereby cooling temperatures in some regions by as much as 0.5 degrees C. An eruption the size of Mount Pinatubo could affect the weather for a few years. http://vulcan.wr.usgs.gov/Outreach/AboutVolcanoes/do_volcanoes_affect_weather.html
E>H Volcanoes Haze Cause Rain. Some research indicates a warmer Earth. Other research seemed to state the opposite. For Mt. Pinatubo, it was also said that the mild cooling effect of these eruptions helped to decrease the effect of global warming. The slight decrease in global temperatures in the few years following a volcanic eruption is caused by the presence of aerosols in the atmosphere. These particles are light in color and reflective in nature. This aerosol layer resembles a “haze.” The effects of this haze can cause increased rainfall and snowfall (H). The aerosols act as condensation nuclei upon which cloud droplets can cling, thus forming precipitation. The amount of moisture formation is proportional to the concentration of aerosols in the atmosphere. http://bigmac.civil.mtu.edu/home/classes/ce459/public/p14/climate.html
E>H 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
E>H Glaciers Connection with Volcanic Actvity. 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
E>H 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
E>H 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
E>H Another problem that is seen in Hawaii’s involves the formation of vog, or volcanic fog. The ongoing eruption is very quiet, with lava flowing through lava tubes and then into the ocean. Up at the vent is an almost constant plume of volcanic fume that contains a lot of sulfur dioxide. This SO2 combines with water in the atmosphere to form sulfuric acid droplets that get carried in the trade winds. http://volcano.und.nodak.edu/vwdocs/frequent_questions/top_101/oldEffects.html
E>H 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
E>H 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
E>H 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
E>H 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
E>H The dried lava from volcanoes can slow down or stop the flow of water resources in a particular area.
Hydrosphere & Event Interactions
H>E Some research suggests that periods of glaciation may cause volcanic eruptions. It is suggested that hydrostatic unloading of the ocean basins during glaciation favors the upward movement of magma and thus may lead to volcanism. During periods of glaciation, oceans are typically smaller and shallower, since a large portion of the available water is frozen in a glacier. Since the oceans has less burden on them, the plates underlying them may shift, which could trigger deep magma bodies, and reactivate them and the fault systems associated with them. This is one way how volcanism might be caused. http://bigmac.civil.mtu.edu/home/classes/ce459/public/p14climate.html
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 Gree
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 Pintubo, mudflows engulfed roads, bridges, and several villages. Not only was the eruption bad enough but the rainfall caused even greater destruction. Closer look at Volcanoes by Jen Green.
Sphere>Sphere Interactions
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. Source: EPA-Climate Change-Office of Policy, Planning and Evaluation-September 1997.
A>H 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. Vulcan.wr.usgs.gov
A>H Water bodies receive large amounts of volcanic ash and debris. Falling ash could cause a change in the pH of surface water.
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.
Closing
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 and natural resources.
Resources – Many sources are documented within the analysis, other sources of information are included below.
http://earthobservatory.nasa.gov/Study/AstronautPinatubo/
http://earthobservatory.nasa.gov/Study/Volcano/
http://www.usgs.gov/public/press/public_affairs/press_releases/pr1538m.html
http://www.ussartf.org/volcanoes.htm