Volcanoes
This paper will define and discuss the volcano to include: types of volcanoes,
formation of a volcano, and elements of a volcano; such as, lava, rock fragments, and gas.
This paper also tells a little bit about volcanic activity in different parts of the world.
What is a volcano?
A volcano is a vent in the earth from which molten rock and gas erupt. The molten
rock that erupts from the volcano forms a hill or mountain around the vent. The lava may
flow out as a viscous liquid or it may explode from the vent as solid or liquid particles.
Kinds of Volcanic Materials
Three basic materials that may erupt from a volcano are; 1. lava, 2. rock
fragments, and 3. gas.
Lava
Lava is the name for magma that has been released onto the Earth's surface. When
lava comes to the Earth's surface, it is red hot and may have temperatures of more than
2012 degrees Fahrenheit. Fluid lava flows swiftly down a volcano's slopes.
Sticky lava flows more slowly. As the lava cools, it may harden into many different
formations. Highly fluid lava hardens into smooth, folded sheets of rock called pahoehoe.
Stickier lava cools into rough, jagged sheets of rock called aa. Pahoehoe and aa cover
large areas of Hawaii, where the terms originated. The stickiest lava forms flows of
boulders and rubble called block flows. It may also form mounds of lava called domes.
Other lava formations are spatter cones and lava tubes. Spatter cones are steep hills
that can get up to 100 feet high. They build up from the spatter of geyser-like eruptions of
thick lava. Lava tubes are tunnels formed from fluid lava. As the lava flows, its exterior
covering cools and hardens. But the lava below continues to flow. After the flowing lava
drains away, it leaves a tunnel.
Rock Fragments
Rock fragment are usually called tephra and are formed from sticky magma. This
magma is so sticky that its gas can not easily escape when the magma approaches the
surface or central vent. Finally, the trapped gas builds up so much pressure that it blasts the
magma into fragments. Tephra consists of volcanic dust, volcanic ash, and volcanic bombs,
(from smallest to largest size particle).
Volcanic dust consists of particles less than one one-hundredth inch in diameter.
Volcanic dust can be carried for great distances. In 1883, the eruption of Krakatau in
...e morphed it into the quartzite that is seen surrounding the butte (4). Rocks that undergo this process are called metamorphic rock, which is the same as the rock seen years ago by dinosaurs and other extinct creatures. The quartzite rocks were formerly seafloor sediment that was forced upwards, and then surrounded by lava basalt flows. Once erupted through fissures and floods through out most of the area, lava flow eventually created enough basalt to form a thickness of about 1.8 kilometers (1). All of this basalt flow eventually led to the covering of most mountains, leaving the buttes uncovered. The igneous lava flows and loess is reasons that the Palouse consists of such sprawling hills, and rich soil for farming (2). In result of the lava flows, the Precambrian rock Quartzite was formed. And lastly covered by the glacial loess, which were carried by the wind.
Shown in the picture above is volcanic extrusive igneous rock known as andesite. They were imported here to Laguna Beach to help minimize erosion (Merton Hill, p. 10-11). Extrusive Igneous rocks are formed on Earths surface due to lava quickly cooling or mixing with different materials such as ash or cinders from an eruption. There are two different types of extrusive igneous rocks; Plutonic and Volcanic. Andesite is known for being gray in color and being made up of very coarse grainy textures, which make it much harder to break down than sedimentary rocks. Unlike loose gravel and other sediments igneous rocks are known for being able to slow down seismic waves from earthquakes which cause less damage to surface structures.
Quartzite is a non-foliated metamorphic rock. This rock is intrusive and forms when exposed to extreme amounts of heat and pressure. Over a billion years ago, there was an ocean where Kamiak Butte is. This ocean floor was made of sand, as time went on oceans receded and the exposed sand underwent processes that turned it into sandstone – or as we learned in class the process of lithification. Years later, this sandstone would morph into the quartzite that is present now.2
On May 22, 1915, an explosive eruption at Lassen Peak devastated nearby areas and rained volcanic ash farther 200 miles to the east! This explosion was the most powerful in a series of eruptions from 1914 through 1917. ...
The last eruption of this massive volcano occurred more than 115 years ago in 1884. The eruptions of Mount Rainier produce lahar mudflows which are similar to pyroclastic flows except they contain more water. These mudflows carry debris of volcanic ash and boulders that produce lava flows and have the consistency of concrete flowing down a mountain (C.M. Riley. Lahars can flow up to 100 kilometers per hour and can extend to more than 300 kilometers in distance. Because they are hard to predict, give off little warning signs, and move so rapidly through valleys, lahar slides are considered to be one of the most deadly volcanic hazards.
Basalt forms due to the partial melting of the layer of the mantle called the asthenosphere. The asthenosphere is the plastic zone of the mantle beneath the rigid lithosphere. Mantle plumes coming from the mesosphere can cause the asthenosphere to melt with heat or even if pressure decreases, which is called decompression melting (Richard 2011). The magma that forms from this melting is mafic magma that solidifies once it reaches the earth’s surface and cools quickly. The above process mainly occurs mainly during intraplate igneous activity which is the main explanation for volcanic activity that occurs a long distance away from a plate boundary. If the tectonic plate above the mantle plume is moving it can create a string of volcanic activity such as in Hawaii. See Fig 2.
Stories about volcanoes are captivating. Myths come in different versions, but all of them are capable of capturing yours, and everybody’s imagination.
same liquid rock matter that you see coming out of volcanoes. On Earth's surface, wind and water can break rock into pieces. They can also carry rock pieces to another place. Usually, the rock pieces. called sediments, dropped from the wind or water to form a layer.
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.
Volcanoes can be one of the most destructive forces on Earth. It is estimated that some
From modern examples and records we know that volcanic activity can set of a chai...
Igneous rocks are formed from the ejection of earth’s volcanoes. Deep down inside earth’s mantle there lies hot magma. Magma is molten rock that is kept below the surface. This mixture is usually made up of four parts: a hot liquid substance which is called the melt; minerals that have been crystallized by the melt; solid rocks that have made themselves tangled in the melt because of loose materials, and finally gases that have become liquid. Magma is created by an increase in temperatures, pressure change, and a alter in composition. When this magma is ejected from earth’s crust it earns a new name called lava. The lava hardens and becomes an Igneous rock.
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.
The interior structure of the earth is made up of crust, the mantle and core (inner core and outer core). Earthquakes occur on the crust. Crust forms the external layer of the earth surface. On the crust, the plate tectonics forces are in charge of causing the abrupt earth movements. Due to the existence of an immense temperature and concurrent pressure difference in the outer layer and inner layer of the earth, convection currents occur at the mantle. This energy results from overwhelming decomposition of radioactive substances contained by the rocks found at the interior of the earth. The developed convection currents lead to movement of lava; cold lava finds its way to the interior of the earth crust, while the molten lava which is generally hot, leaves the interior of the earth to the outside of the earth crust. These kinds of circulations occur at different locations of the earth surface and consequently results in segmentation of the earth due to movement in different directions.