In this essay, I will analyse the different types, geochemistry, constitution, identifying characteristics and consequential activity levels of volcanoes, with a particular focus on Stratovolcanoes and how they compare to the other known types and specifically the magma constituency, viscosity levels and mineral content when compared to that of other types of volcano.
Stratovolcanoes which are also commonly known as composite volcanoes are composed of many different strata or layers of pyroclastic materials, pumice, volcanic ash and igneous rocks. They tend to have similar eruption patterns that ordinarily results in very significant pyroclastic flows indicated by a fast moving build-up of ash and gas as the upper basal, and pumice and hot lava as the lower basal. From experienced occurrences, these Stratovolcano pyroclastic flows produce great energy and flow speed and have potentially destructive power, as was experienced during the Armero Tragedy which was a direct consequence of an eruption of the Nevado Del Ruiz stratovolcano in Tolima, Colombia in November 1985.
Stratovolcanoes can also produce deadly lahars, or volcanic mudflows, consisting of water and rock fragments and particles referred to as tephra. A lahar has a consistency akin
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A lava dome referred to as a “resurgent dome” and was formed after caldera collapse caused by a gradual up warp from the caldera floor consisting mainly of pyroclastic flows of pumice being given out and deposited from a caldera-forming eruption. On the other hand, the giant rhyolitic dome (which is the most central dome) was formed due to a subaqueous lava build up on the caldera floor. Whether or not this lava dome is monogenetic or composite is still
Let’s begin with a little knowledge of Mt. Rainier and Yellowstone. Well, they are both in Washington. Rainier’s last few eruptions had lahars; we know this because of previous paths of destruction. This volcano is dormant, just blowing off a little steam sometimes. The last lahar was 500 years ago. If that happened again,
Mount Tambora, located on the Island of Sumbawa, Indonesia is classified as a Stratovolcano. Also known as a composite volcano, Tambora is a tall conical volcano (cone like structure) where layers of the walls are built by hardened lava and volcanic ash. The term composite is used to describe the volcano due to the composite layered structure built from sequential outpourings of eruptive materials1. Among the most common types of volcanoes, Tambora also shares its destructive prowess with best-known volcanoes such as Krakota (1883) and Vesuvius (79 A.D). The Island of Sumbawa is located in the middle of the Lesser Sunda Islands chain (a group of islands in the southern Maritime Southeast Asia) and is in the province of West Nusa Tenggara3. A map of Mount Tambora is shown in Figure 1 to provide a better perspective of its location. Interestingly enough, Tambora forms its own peninsula on Sumbawa, known as the Sanggar Peninsula. In April of 1815, after years of dormancy, Mount Tambora erupted with great intensity, approximately 7 on the volcanic explosivity index, which is shown in Figure 2. It has been estimated that the eject volume of Tambora was 160 cubic kilometres, which represents the largest volcanic eruption in recorded history. The death toll has been projected to be at least 71,000 people, of who over 15% were killed directly from the eruption1. The remaining 75% have been thought to succumb to starvation and disease, as the eruptive fallout decimated the agricultural industry in the region. Following the eruption, a volcanic winter ensued. As sun become less abundant due to clouds of ash, crops and livestock perished. Please note that all definitions appearing in the footnotes are either taken from already referenced so...
Volcanoes can be very deadly but the location can also determine that. Zones are what tells people how dangerous they are. In document c it explains each zone. There are five zones by one being the harshest zone and five being the safe zone. People live in all zones and that's not good at all. Documents C says " There is an area around an active event where likelihood to be killed is extremely high." Volcanoes are always capable of surprises and never up to something good.
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 out 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.
MILLER, C. D. POTENTIAL HAZARDS FROM FUTURE ERUPTIONS IN THE VICINITY OF MOUNT SHASTAVOLCANO, NORTHERN CALIFORNIA. N.p.: US Government Printing Office, 1980. Print.
The eruption on Mount Saint Helens has a specific cause and comes with many effects. A multifold of people would say that the “mountain looked like the site of an atomic blast” (Bredeson 30). That is a very accurate depiction as it took great power to inflict as much damage as it did. The reason for this impressive amount of force is that when magma is built up with pressure and an earthquake hits, the pressure gets magnified and the volcano explodes (Lewis). This is exactly what happened inside Mount Saint Helens. Furthermore, it has been revealed that “The earthquake that triggered the explosion was a 5.2 on the Richter scale” (Gunn 559). The earthquake to the magma can be compared as a match to gasoline. Even though the earthquake was not huge, the scale of the eruption was much greater than that of the earthquake (Gunn 560). The earthquake was only the trigger that allowed for more devastating things to occur. Thirteen hundred feet of the volcano were lost in the explosion followed by landslides, mudslides, and lava flows...
Like most of the other volcanoes in the Cascade Range, St. Helens is a great cone of rubble, consisting of lava rock interlayered with ash, pumice and other deposits. Volcanic cones of this internal structure are called composite cones or stratovolcanoes. Mount St. Helens includes layers of basalt and andesite through which several domes of dacite lava have erupted. The largest of the dacite domes formed the previous summit; another formed Goat Rocks dome on the northern flank. These were destroyed in St. Helens' 1980 eruption.
Stories about volcanoes are captivating. Myths come in different versions, but all of them are capable of capturing yours, and everybody’s imagination.
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
Volcanoes can cause damage by spewing lava, but earthquakes before the eruption can also cause damage. These earthquakes open fissures and let magma out to the surface. When the magma exits these fissures, streams of lava up to hundreds of feet can shoot into the air. The picture below shows the lava erupting from the fissures created by the earthquakes in...
From modern examples and records we know that volcanic activity can set of a chai...
channel migration, the eruption of a volcano, the drying of a lake, or the destruction of a
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.