| Physical Geology 2005 |
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Source of Photo:
U.S. Geological
Survey. Home Page. http://pubs.usgs.gov/publications/text/fire.html Accessed
March 2005
Related Links
Source of photo: http://volcano.und.edu/vwdocs/frequent_questions/top_101/Volcanoes/Volcanoes7.html Accessed March 2005
<Effects
Volcanoes can be very destructive incidents, causing damage to buildings,
injuries, and deaths. Land upheavals of this nature can change the surrounding landscape, blasting away mountain, changing topography,
and forming surfaces of cooled lava. Volcanoes can also cause many other natural disasters, including tsunamis, avalanches, and
heavy rains that combine with ash to create lahars (volcanic mudflows and debris flows).
Prevention Currently it is impossible to prevent a volcanic eruption, but it is possible to keep damage to a minimum. In 1973, citizens of
Iceland poured cold water onto flowing lava to slow it down, an act that helped save the fishing port of Heimay. In Sicily,
on Mount Etna, engineers have blasted holes in the hard crust covering a lava flow using explosives. The lava then turns to
flow out through the holes instead of swallowing villages in its original path.
As increased reporting and computer analysis continue, we are gaining more and more knowledge of eruption frequencies and
durations. Hopefully, this information can help us to prepare for future volcanic activity. Advantages But volcanoes are not only disastrous. They can be helpful too. The rocks produced from volcanic pressure form most of
the ocean floor and continents. Early volcanoes produced steam that later became the water that we cannot live without,
as well as the oxygen we need to survive. Volcanic ahs and lava also form rich soil, while hot rocks heat underground water.
In some countries such as Ireland, it forms hot springs. Engineers are trapping the steam heated by volcanic rock
to produce electricity or hear for cities.
Although volcanoes are usually linked to death, destruction, and tragedy, they do have some often-overlooked benefits.
In New Zealand, people often visit the hot mud baths of Raupehu. More than eight hundred wells exist in Rotorua, a popular
spot for those seeking hot water baths, large community swimming pools, natural hot-water tubs, hot-water-heated rooms,
and steaming hot springs. The medical and health benefits of such relaxing spas are also highly recommended.
Volcanic ash also serves as a natural resource for construction and industry. Lava and tuffs can be cut into
blocks and used as stone for buildings. Tuff can be cut into blocks that are used for weathering, and good insulators.
Fine-grained volcanic ash is used as a polishing compound, and can be found in toothpaste and household scrubbing
compounds. Concrete, too, was discovered by Romans who mixed granular volcanic ash with lime cement to create a new,
water-resistant material with superior strength. It was this substance that allowed the Romans to build fantastic
edifices, water works, aqueducts, roads, harbors, underwater structures, and lighthouses. It is still used in
concrete constructions today.
Cinder cones have also been mined as a source of construction materials. Pumice was used by Mediterranean
peoples as an exfoliant scrub and abrasive cleaner. Obsidian, a shiny black volcanic glass, has been
fashioned into arrowheads and knives, traded, quarried, and even used in eye surgery. Volcanic ash is
used as filler in adhesives, ceramics, bread, and ice-milk products. Volcanic ash is also a major ingredient
in cat litter because it easily absorbs moisture.
Volcanoes are also great tourist attraction. Such monuments as Mount Vesuvius and Mount Fuji are awe-inspiring symbols for their respective nations. Vesuvius was an important destination for artists, writers, poets, and dignitaries. Today, the Hawaiian volcanoes are a great source of tourism.
Geothermal energy is a constant but often under-utilized source of electric power. Environmentally friendly and renewable, this water can be used for growing fish, fruits, and vegetables, drying foodstuffs, and heating residential and commercial buildings. In Iceland, geothermal waters are even piped to homes for bathing and food preparation.
New evidence has also emerged that volcanic areas can be prime petroleum sources. Geothermal systems can also serve an important part in petroleum generation, migration, and entrapment. Many oil-bearing seafloor sediments have been found near hydrothermal vents at mid-ocean ridges. Shell Oil Company also found much oil in volcanic regions in Nevada in 1954, leading to the discovery that volcanic ignimbrites are excellent storage spots for oil pools.
High-energy geothermal systems are also some of the most efficient natural concentrators of valuable ore minerals. Some hot springs in Waiotapu, New Zealand, contain large amounts of gold. At another hot springs, mercury condenses from rising stream at the bathhouses. Many metals, like gold, silver, copper, molybdenum, lead, and zinc have been found beneath such springs.
Volcanic soils are also some of the richest on earth, providing lush farmland. The best coffees are also grown in volcanic soils in a tropical climate, between elevations of 1,400 and 1,700 meters. These conditions are most commonly found on young, active volcano slopes.
Volcanic rocks are rich in nutrients needed by plants. They are so rich, in fact, that they are considered as “hard” fertilizer. There rich soils encourage farming, agriculture, and population growth.
The constant fall of volcanic ash is also ideal for preserving surface conditions at the time of deposition. Able to bury things intact without moving, crushing, or burning them, volcanic rock is an excellent source for fossils.
Volcanoes also bring diamonds up from deep in the earth. Other precious gems, like the red beryl, or “red emerald” is even rarer than diamond, but can be found in the Wah Wah Mountains in the United States.
The Ring of Fire
The Ring of Fire is an arc stretching
from New Zealand, along eastern edge of Asia, north across the
Aleutian Islands of Alaska, and south along the coast of North
and South America. It is composed of over 75% of the world’s
active and dormant volcanoes.
Ring of Fire
http://www.crystalinks.com/rof.html
Accessed March 2005
Major Volcanic areas
in the Ring of Fire:
1. In South America the Nazca plate is colliding
with the South American plate. This has created the Andes and volcanoes
such as Cotopaxi and Azul.
Source of photo: http://www.james.wrighton.btinternet.co.uk/Ecuador/cotopaxi.jpg Accessed March 2005
2. In Central America, the tiny Cocos plate is crashing into the North American plate and is therefore responsible for the Mexican volcanoes of Popocatepetl and Paricutun (which rose up from a cornfield in 1943 and became an instant mountain)
Source of photo: http://www.horolezec.cz Accessed March 2005
Source of photo: http://www.horolezec.cz Accessed March 2005
3. Between Northern California and British Columbia, the Pacific, Juan de Fuca, and Gorda plates have built the Cascades and the infamous Mount Saint Helens, which erupted in 1980.
Source of photo: http://www.iseran.com/Expeditions/msh.html Accessed March 2005
4. Alaska’s Aleutian Islands are growing as the Pacific plate hits the North American plate. The deep Aleutian Trench has been created at the subduction zone with a maximum depth of 25,194 feet.
5. From Russia’s Kamchatka Peninsula (Kliuchevskoi) to Japan, the subduction of Pacific plate under the Eurasian plate is responsible for Japanese Islands and volcanoes (such as Mt.Fuji)
Source of photo: www.hyperfrank.com/ RSRC/fuji-2-small.jpg Accessed March 2005
Source of photo: www.hyperfrank.com/ RSRC/fuji-2-small.jpg Accessed March 2005
6. The final section of the Ring of Fire exists where the Indo-Australian plate subducts under the Pacific plate and has created volcanoes in the New Guinea and Micronesian areas. Near New Zealand, the Pacific Plate slides under the Indo-Australian plate.
The volcanic and seismic activity of the Ring of Fire was noticed and described before the invention of the plate tectonics theory. The Ring of Fire is located at the borders of the Pacific Plate and other tectonic plates.
A volcano is a place on the Earth’s surface (or any other planet’s or moon’s surface) where molten rock, gases and pyroclastic debris erupt through the earth’s crust. Volcanoes vary quite a bit in their structure – some are cracks in the earth’s crust where lava erupts, and some are domes, shields, or mountain-like structures with a crater at the summit.
Magma is molten rock within the Earth’s crust. When magma erupts through the earth’s surface it is called lava. Lava can be thick and slow moving or thin and fast moving. Rock also comes from volcanoes in other forms, including ash (finely powdered rock that looks like dark smoke coming from the volcano), cinders (bits of fragmented lava), and pumice (light-weight rock that is full of air bubbles and is formed in explosive volcanic eruptions – this type of rock can float on water). Volcanic eruptions can cause great damage and the loss of life and property.
Source of photo: http://www.enchantedlearning.com/subject/volcano/ Accessed March 2005
According to the tectonic
theory, the surface of the Earth is made up of a patchwork of massive rigid
plates, about 80km thick, which float in slow motion on top of the Earth’s
hot, pliable interior. The plates change size and position over time, moving
at speeds of between 1cm and 10cm every year – about the speed at
which fingernails grow. New sea bed is constantly being created in the
middles of the oceans – flowing out as hot lava, and rapidly cooling
on contact with cold deep-sea water. To make room for the continual addition
of new ocean crust, all the earth’s plates move. And as they move,
intense geologic activity occurs at the plate edges. At the edges, on of
three things may occur:
1. The plates can be moving away from each other, leaving space for new ocean floor.
2. Some plates are moving towards each other, causing one to submerge beneath the other.
3. Other boundaries slide past each other without much disturbance.
Parts of the plate boundary that slide past one another in opposite directions – such as the San Andreas Fault – cause minor earthquakes. The faults may also create cliffs or scraps thousands of feet high on the ocean bed. But where one oceanic plate collided with and is forced deep into the Earth’s interior, the subsumed plate encounters high temperatures and pressures that partially melt solid rock. Some of this newly formed magma rises to the surface and erupts, forming chains of violent volcanoes – like the Ring of Fire. These narrow plate-boundary sites, known as subduction zones, are also associated with the formation of deep ocean trenches and big earthquakes.
Around the Ring of Fire, the Pacific Plate is colliding with and sliding underneath other plates. The process is known as subduction and the volcanically and seismically active area nearby is known as a subduction zone. There is a tremendous amount of energy created by these plates and they easily melt rock into magma, which rises to the surface as lava and forms volcanoes.
The Earth's Ring of Fire And Plate Tectonics. BBC News - January 29, 1999.This information was obtained through the Ring of Fire website available from http://www.crystalinks.com/rof.html Accessed March 2005
Link to other Student Webpages for 2005 Earlham Physical Geology
This website was
prepared as an assignment
for Geosciences 211 (Physical Geology)
taught in the spring of 2005 at Earlham College, Richmond,
Indiana.
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Earlham College· Geosciences Department · Earlham Geosciences 211: Physical Geology |
Copyright © 2005 Earlham College. Revised April 11, 2005 . Send corrections or comments to parkero@earlham.edu