Where continental plates drift apart, the major landform created is a rift valley, for example that in East Africa. The doming up of the crust, as a result of the intense pressure from the convection currents within the mantle, leads to rocks splitting at their weakest point. Rift valleys occur where two parallel down- faults have produced a trough. The East African rift valley, beginning at river Jordan, stretches for over 4,000km. It is situated where the Arabian plate has separated from the African plate. Volcanoes are associated with the eastern rift, for example in Kenya and Tanzania, as the faults create an easy route for the lava to escape and reach the surface. This is a picture showing the Great Eastern rift valley.
The conservative type plate boundary is where two plates pass each other rubbing in opposite ways. This friction is the main cause of earthquakes. If you compare a map showing where the conservative margins are located and where the world’s earthquakes mainly occur, you will find evidence of this.
One example of an earthquake that occurred on a conservative plate margin is the 1999 earthquake, in Izmit, in western Turkey. The industrial city is located on the plate margin between the Eurasian and the Anatolian plates. The earthquake occurred in the early hours of the morning on 17th August and reached 7.8 on the Richter scale. Over 2000 fatalities were recorded and tremors were felt over 200 miles away. The human consequences were severe; the primary effects were that Multi – story apartment blocks, oil refineries, roads, bridges and power lines were all destroyed in the area.
Turkey is a less economically developed country and does not have the equipment to predict earthquakes before they occur; therefore an earthquake that happens here would cause more devastation and fatalities than an earthquake that occurred in a country that was prepared
Many things need to be restored after an earthquake has occurred, and this can be even more economically straining to an unprepared LEDC. Rebuilding of cities, businesses and lives takes years, and it is unknown that if when they finish the restoration, another earthquake might hit again.
People still build settlements and take homes in areas of great danger, whether next to a volcano or on a high-risk earthquake area. This is because of the economic value of such a dangerous place; in time volcanic rocks produce highly fertile soil. This is extremely good for agriculture and brings the people an income. These areas often offer beautiful scenery; this has a great impact on tourism in an area. Many people still visit the yellow sand national park. Mineral wealth and geothermal energy is of great availability, for example hot water from geysers.
The conservative plate margin that receives the most publicity and greatest scientific study is in California. The north American plate is almost completely still, however the pacific plate is moving in a north westwards direction by 10cm a year. The largest and best-known fault here is the San Andreas. In 1089 the Loma Prieta earthquake suffered a great loss of life. However California and areas like it, which have frequent earthquakes, have ideal climate, perfect soils and plenty of resources. People have learnt to adapt to the earthquakes. Many buildings are built reinforced, or older buildings are retrofitted, where they are made earthquake proof after they are built. However this is expensive and cannot be done in a less economically developed country, which causes many old buildings to be destroyed. This is a picture of California showing the plate movement and margin.
Destructive plate margins occur when two plates converge. One plate is destroyed as it is subducted into the mantle and melted. The other plate is forced up and over it. Pressure from colliding plates causes the crumpling and folding of sediments to form mountain ranges, oregenis. This can be seen in the Alps, the Rockies and the Himalayas. Destructive margins are areas of intense seismic activity as magma reaches the surface through faults creating frequently violent volcanic eruptions. These types of margins are mainly situated around the Pacific Ocean.
Italy is located on a destructive plate margin, where the Eurasian plate and the Hellenic plate are colliding. There are three volcanoes found here, Vesuvius Stromboli, and Etna. Vesuvius is 1, 277m high. It was thought to be extinct before it erupted in AD79 with a glowing cloud of hot fuming ash. Pompeii and Herculaneum, which were two thriving roman cities, were destroyed. It is thought to erupt every 30 – 50 years; the last one was in 1944, so there is one scheduled soon. However a population density of 800/sq km lives around the area of Mount Vesuvius. Its black lava has weathered into fertile soil. This is perfect for farming. This is a picture of the Italy and where its three volcanoes are situated.
Volcanic activity produces extrusive and intrusive landforms. Intrusive include batholiths, dykes, sills and laccoliths where the magma has intruded into, or between existing rocks under the ground. Extrusive landforms involve volcanic cones, lava plateaus (where lava flows out of a constructive plate margin covering a vast area in its runny, smooth lava), and other minor forms of volcanic activity. Hot springs, boiling mud and geysers, when water infiltrating from the surface comes into contact with a fissure, sends a powerful jet of boiling water to rise many metres into the air periodically. These can be found in Iceland
Volcanoes are the main geographical features here. Mount Pinotubo, in the Philippines erupted between the 12th and the 16th of June 1991. It was a dormant volcano that hadn’t erupted for 100 years. Towns 50 miles away were buried in ash and dust, Hundreds and thousands of people were left homeless and half of the areas animals died. This was because they could not graze. Dust and ash in the atmosphere, intercepting the light from the sun was thought to reduce the global temperatures for 5 years. However, after all of this devastation, only 500 people died altogether. This was due to accurate forecasting which enabled the area for 15 miles to be evacuated.
As magma rises up into and through the volcanic zone, there are warning signs, steam and the releases of gases, e.g. hydrogen sulphide. Technology is used to help the prediction, satellites can monitor heat changes, which is of great help to LEDC’s that do not have the money to have ground monitoring stations.
However earthquakes are harder to predict and the best people can do is prepare, which costs money. This is where LEDC’s suffer more when they are hit by a natural disaster. They do not have the money to prepare sufficiently, and then do not have the money to restore afterwards.
If we had no knowledge of how plate tectonics, how they work and what features they create, many more people would die when disasters strike, and the world would suffer more economically. By managing these, we cannot prevent an earthquake, volcanic eruption or tsunami from occurring, but we can predict when, and how badly they will occur.