While one might ask how water erosion can be so prevalent in the desert, it is important to note that like many Australian deserts, the area receives a surprisingly high amount of rain, about 200-250 millimeters a year. ("Ayers Rock Facts," 2009) It is believed that the mountain chains that once included Ayers Rock were as large as the surrounding peaks. Now, there is just one remaining piece of this long lost chain. Wind and water took an enormous toll on the surface of the area. When one considers other major mountain chains, and is informed that they were once much larger, it is hard to grasp the concept due to the fact that the mountains still exist, and are fairly large in their current state.
I will be discussing factors that cause differences in hazards posed by volcanoes. I believe the most important factor is the location of a volcano and the type of volcano. The most explosive and therefore dangerous volcanoes are found on destructive plate boundaries (Over 80% of the worlds volcanoes occur at these boundaries) for example the eruption of the Nevado del Ruiz in Colombia on the 13th November in 1985 which killed over 25000 residents of Arenas and Armero. At destructive plate margins, the oceanic crust is denser than continental crust and is therefore subducts under the continental crust. Due to high temperatures in the mantle of around 3000 degrees centigrade, this oceanic crusts melts and then rises due to the convection currents in the aesthenosphere .
In which ways does volcanic activity vary in relation to the type of plate margin along which it occurs? (10 Marks) Volcanic activity can occur at constructive or destructive plate margins, but it can also occur at hotspots in which no plate margin is involved. At destructive margins two plates which are moving together can be either both oceanic plates or one continental and the other oceanic. In the case of one continental plate and one oceanic plate, volcanic eruptions are very violent and emit andesitic or rhyolitic lava. These types of lava are very viscous due to its high silica content.
Generally the Californian society’s capacity to cope is high and thus they are affected differently! On the other hand The Philippines consists of 7000 islands which are all sited on a destructive plate boundary where the dense oceanic plate is being subducted beneath the Eurasian plate. This generates deep focus earthquakes however with violent volcanic eruptions. For example during 1991 when Pinatubo erupted, around 700 people were killed and the damage was approximately
California’s San Joaquin Valley is one of the states top agricultural regions. It is 240 miles long and bordered by many mountain ranges. Eight counties compromise the San Joaquin Valley. Much of the problem in Americans most productive farm region is simply a function of its unusual geography and climate. Its bowl-like geography causes an entrapment of fog, air pollution and much of the horrible heat waves that are present during summer months.
Plate tectonics and Associated hazards Analyse the factors that cause differences in the hazards posed by volcanoes around the world. (40 Marks) Using case studies we can clearly see the differences in the hazards that volcanoes pose. A hazard is a situation that poses a level of threat to life, health, property or environment. The level of hazard posed by different volcanoes can very greatly, from a weak eruption with minimal impact that causes little damage, to a violent and life threatening explosion. Most of the sixty-plus volcanoes that erupt each year are low risk, however a combination of factors can cause a volcano to be a serious hazard.
Mt. St Hellens is positioned on a destructive plate boundary, this means that two different type of plate are moving towards each other, a denser ‘Oceanic Plate’ (Juan de Fuca Plate) is moving towards a lighter ‘Continental Plate’ (North American Plate). As the Oceanic Plate is heavier as it has a body of water on it, in this circumstance ‘Spirit Lake’ it is forced to subduct under the lighter Continental Plate. When this occurs the plates can stick, this causes a huge amount of friction, heat and pressure to build up. As Mt.
There were several hundred domestic flights in Argentina and Chile and several dozen international flights from Santiago, Chile and Buenos Aires, Argentina cancelled. In addition, Lahars (volcanic ash mud flows) had cut communications in areas and made access difficult whilst ash falls up to 15cm deep had blocked rivers and contaminated water supplies. By
Saint Helen a composite volcano (or stratovolcano), a term for steep sided, often symmetrical cones constructed of alternating layers of lava flows, ash and other volcanic debris. Composite volcanoes tend to erupt explosively pose considerable danger to nearby life and property. Before 1980, snow capped, gracefully symmetrical Mt. Saint Helens was known as the “Fujiyama of America.” Mt. Saint Helens, other active Cascade volcanoes, and those of Alaska form the North
The Sierra Nevada create uplift of moist oceanic air masses and it rains. Much of the water reaches the San Joaquin valley but by the time the storms reach the eastern Sierra and Owens Valley, most of the water has been wrung from the clouds. The White and Inyo mountains, only twenty five miles east of the Sierra crest, are semi-arid. They suck the remaining water from the skies and by the time the air reaches the Saline and Death Valleys, it is bone dry. Such weather patterns have a great influence on the surface geology as well: erosion, deposition and chemical alternation take place rapidly in many parts of