GCSE Geography
Distribution of Volcanoes: Most volcanoes are located on or near plate boundaries in narrow bands. Volcanoes are extremely common on the ring of fire which is a volcanic chain around the Pacific Ocean. The Pacific Plate, an oceanic plate that forms the bed of the Pacific Ocean, is surrounded by a number of continental plates. The movement of these plates create zones of subduction (e.g. where the Pacific and Eurasian plates meet). This leads to the formation of volcanoes and the occurance of earthquakes in these areas. Some volcanoes are disparate to this general trend and occur in the middle of oceans, and example is Mauna Loa, these are hotspot volcanoes and are are a result of plumes of magma rising up through fissures in the Earth's crust.
Scales for measuring Earthquakes: There are two scales for measuring an Earthquake, the richter scale and the mercalli scale, The rickter scale measures the magnitude of an Earthquake and has no upper limit. Eact whole number means ten times worse than the number before. The magnitude of an earthquake can be determined by seimosmeter reading. The mercalli scale measures the damage causes by an Earthquake and is based upon visual observations. The scale goes from I-XII and is in Roman numerals.
How do earthwuakes occur?
When two plates slide past each other, they get stuck due to friction and over time the pressure builds up and is eventually released in the form of seismic waves when rock snaps, this is when an Earthquake occurs. The focus is the point below the surface where the pressure is released and where the snapping of the rock occurs. The epicentre is the point above the surface which is immediately above the focus, this is where the damage occurs.
Living with Hazards
Earthquakes
Hotspot volcanoes- Hotspot volcanoes occur in reas where hot plumes of metal rise to the surface of the crust., an example of a hot spot volcano is Mauna Loa. The hot plumes melt rock and magma rises up through fissures in the Earth's crust and slows erupts to form volcanoes. As the plate moves over the stationary hotspot, the volcano is rafted away and new ones form, this forms a chain of volcanic islands such as the Hawaiian islands. The older volcanoes become dormant or extinct.
Why do people live near volcanoes?
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One of the main reasons why people live near volcanoes is because of the fertile soils which have resulted from previous pyrolclastic flows. Volcanic soild are ideal for agriculture which is a colossal source of income. In Naples, cropss uch as tomatoes and grapes are grown near the volcanic soils of mount vesuvius.
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Another reason why people live nea