The Nature of Vocanic Hazards

Another physical factor is snow; if a volcano is snow capped, like Eyjafjallajokull, then the lahars and flash floods become a greater hazard. The flooding in Iceland in 2010 caused 700 people to be evacuated. Without the snow then lahars and floods may not be a problem at all.

Anpother factor that can have an impact on the level of hazard posed by a volcano is the type of plate margin on which it occurs. Volcanoes occuring at constructive plate boundaries are usually much less violent than those occuring at destructive plate boundaries. This is because the magma produced by plates moving apart is Basic, and therefoe has a low viscosity, allowing it to flow easily. The lava is produced from a central vent or fissure and erupts regularly but not usually violently. Also,constructive plate boundaries are often found under the sea and create submarine volcanoes, such as along the Mid-Atalntic ridge, so pose few threats to humans. As a result, the hazards posed by volcanoes at constructive plat eboundaries is relatively low. However, the subduction of one plate under another at destrctive plat eboundaries can form an acidic magma chamber, due to the build up of intense heat. Acidic magma is very viscous and resisitant to flow, meaning that there is often a huge build up of pressure, which can result in very violent and dangerous eruptions involving ash and pyroclastic flow. This can pose a a serious hazard. Pyroclastic flowsa are extremely dense, containing toxic gases at very high temperatures, and can move at speeds over 100km/h. The consequences of such an unpredictable hazard can be extremely seruous

that the volcano must be classified as dormant rather than extinct. Moreover, the unexpected 1995 eruption of the Soufriere Hills volcano on Montserrat, situated in the same volcanic arc, demonstrates that continuous awareness of the associated hazards is required.

Volcanic activity happens across the surface of the globe therefore bringing hazards to every affected area. A hazard is any source of potential damage, harm or adverse health effects. A volcanic hazard is any threat to life and infrastructure due to volcanic activity and related situations such as a landslide near the volcano. Volcanoes can be very dangerous and therefore present many hazards towards both people and land. They have the ability to kill and destroy, ruining livelihoods and destroying large land masses. The extent of the hazard can differ depending on how prepared an area is for an eruption and how much planning has gone behind

A volcano is an earth hazard that occurs on faults between tectonic plates on a destructive boundary and an eruption is a natural disaster. A primary impact happens immediately after the disaster and before any response like death or collapsing or destruction of buildings. A secondary impact occurs later after the disaster, such less farm produce or a reduction in tourism. The severity of these impacts will differ considerably in a MEDC and LEDC where volcanic eruptions have taken place. These may be seen in the Mount St. Helen volcano eruption as well as in the Iceland volcanic eruption. They may also

Firstly I do not agree with this view I believe it is more to do with the human decisions that make a volcanic eruption a hazard. For example we can see this in such volcanic events such as Mount Pelée which erupted in 1902. In the town of St Pierre there was early warning or an eruption from the volcano. From mid-April animals in the area started dying from poisonous gas realised from the volcano. In early may more signs where

Our claim states “The more silica, the more dangerous the eruption is”. The “Rhyolitic magma” took the longest time to fall, since it contained the most silica making it much more viscis. This eruption would be much more dangerous and have much more of an impact on the land and people surrounding it than the “Basaltic magma” and “Andesitic magma” that contained less silica and had a lower viscosity. These two magmas also took a much shorter time to fall than the high silica magma. This brought us to our analysis that states: “The higher amount of silica, the more time it takes for the magma to descend”. The data and evidence we collected justifies our claim because the more silica you have, the more viscosity is created. A harder viscosity creates a much harder environment for the magma to move, trapping much more gas in the magma and making it a lot harder for the gas to escape. Usually, most of the gas ends up stuck in the magma which leads for this high viscosity magma to cause more explosive, dangerous eruptions. When we discussed our claim with other groups, we all ended up agreeing on the same claim, “The more silica, the more dangerous the chemical reaction”. Other groups took different routes and had different procedures to finding the claim, but we all ended up

A Volcano is a mountain or hill that has a crater running through it filled with lava, rocks, gas and hot vapour that will erupt. There are three types of volcanoes, there is the Cinder Cone volcano which is the smallest, the Shield volcano which is in most cases the biggest and the Composite volcano which can be the most deadly.

Volcanoes are one of the most intimidating natural processes that occur on this planet. Usually they are associated with danger and chaos. Volcanoes are characterized by both their composition and eruption types. In this paper we will be exploring the similarities and differences between three infamous volcanoes, Mt. St. Helens, Mt. Kileaue, and the currently relevant Mt. Agung.

(Cashdollar et al. 1982) A Plinian eruption, also known as a Vesuvian eruption, is an eruption marked by columns of gas and volcanic ash extending high into the atmosphere, as well as a large amount of pumice and very continuous gas blast eruptions. A pyroclastic flow is one of the most dangerous forces released by an erupting volcano. A column of hot gas and ash is thrown into the air and collapses under its own weight. It then roars down the side of the volcano, obliterating everything in its path. (Watson 2011) The collapse of the gases in the pyroclastic flow was divided into several surges, and it is believed that surges 4 and 5 destroyed Pompeii. Pompeii, along with Herculaneum, was mostly destroyed and buried under 4 to 6 meters of ash and pumice. (Santillo Frizell 2006)

However, scientists have discovered that there is a tear underneath Vesuvius. The lower part of the subducting African plate is torn and detached from the upper plate, forming a “slab window.” Vesuvius rest right above that slab window. This makes the rocks of Vesuvius chemically different from the other volcanoes in the Campanian arc (Ball). The tear allows heat from the Earth’s mantle to melt the plate, which builds up pressure and causes more violent and explosive eruptions (Bagley). Stratovolcanos like Vesuvius are usually formed from alternating layers of pyroclastic debris and lava flows. The magma present at Mount Vesuvius is andesitic, making it an intermediate composition (Sabatino). The force of the eruption was almost 100,000 times greater than the force of the nuclear bomb in Hiroshima (Cartwright). Because of the magma composition, the gases present in volcanoes could not escape. As more gas was trapped, it eventually leads to the deadly eruption when the volcano could no longer contain the amount of gas in the mountain. The volcano has erupted more than 50 times since the eruption of 79 C.E. Originally, Vesuvius was thought to have a 20-year eruption cycle. However, the last explosion was in 1944, making another catastrophic eruption long overdue (Bagley).

Volcanoes are typically classified as a natural disaster. This is mainly because of their destructive nature to the environment and society. Eyjafjallajokull is a subgalcial volcano based in Iceland. Its structure consists of a caldera-crater at its top and its overall volcanic structure is a stratovolcano. Eyjafjallajokull is a great example of a volcano which has the ability to cause major issues in terms of society and the environment. Although, Eyjafjallajokull’s most recent major eruption, which lasted through March 20 2010 – June 23 2010, didn’t cause any deaths, it still caused great damage to its surrounding environment, with its eruption releasing tephra, ash, lava and dirty thunderstorms. Eyjafjallajokull’s eruption

The volcanoes are located where there is a divergence or convergence in the tectonic plates and bring their lava from the deepest of the terrestrial mantle. The materials and explosions of these ginates represent a constant risk in the places inhabited by the human being, nevertheless the people ususually live in these areas no matter the risk. On the other hand the volcanos can change the geology of an impressive form, or to cool the temperature of the earth, or to darken the sky. The scientific community increases its efforts to try to understand better what happens in volcanoes, however it is impossible to predict these conditions.

Throughout the first eight weeks of Physical Geology I, I have learned more about the Earth, how it works, and natural disasters than I have in my entire educational career. We have analyzed everything from the different types of rocks to several different natural disasters such as volcanoes and earthquakes. However, one thing in particular caught my attention and fascinated me through its sheer power and destruction. Volcanoes are intriguing, and they have the force and destructiveness to wipe out an entire population.

In these eruptions, instead of the mixture of gas and ash flowing upwards, it flows outwards and hugs the ground. These eruptions are extremely dangerous.