1. According to dictionary.reference.com an earthquake is a: Series of vibrations induced in the earth's crust by the abrupt rupture and rebound of rocks in which elastic strain has been slowly accumulating. The earth is made up of tectonic plates these are massive slabs of rock floating on magma ,as the plates move about, they spread apart, collide, or slide past each other, This is the main cause of volcanoes and earthquakes Earthquakes occur in many regions all over the world in some regions they occur more frequently and severely than in others (depending on the location), the main cause of earthquakes is tectonic plates grinding against each other , therefore earthquakes occur more frequently and more severely in these regions , less commonly earthquakes are caused by volcanic activity in this case they either proceed or ac company eruptions . Volcanoes
Volcanoes are formed when plates collide or move away from one another thus they are usually found at the edge of tectonic plates .Volcanoes can also occur in the interior of plates, these volcanoes are commonly known hotspots.
MOVEMENT OF TECTONIC PLATES
2. Tsunamis can be formed by :
Underwater earthquakes are the most common cause of tsunami’s .If an underwater earthquake is large enough, significant movements will be made by the ocean floor, pushing up the ocean water upward causing a large ripple that begins to travel through the ocean at a speed of 600miles/h. because the ocean is so deep, the wave is not limited by space resulting in plenty of room to move around, as it gets nearer to the shore the wave size increases in height as the water becomes shallower . Eventually the wave will hit the shore and travel further inland.
There are three different ways that volcanoes can cause tsunamis : a land-based volcano can break down and collapse, forcing large amounts of ash and rubble into the water. This sudden change and displacement of the water column transfers to kinetic energy (movement energy) and results in waves. More debris can create a bigger increase in wave size and amount. An offshore or submarine volcanic eruption can create high magnitude lifts on seafloors, which pushes large water columns upwards creating a tsunami. The collapsing of a submarine volcano's slope creates a sudden disturbance in the water resulting in tsunami waves.
Tsunamis are often generated by a submarine landslide, which usually occurs because of an earthquake, (shaking unsettles coral, rock, or ice formations causing them to fall). A submarine landslide, rock fall, or ice fall can trigger a tsunami by displacing large amounts of water. This causes a rise in water levels, generating a tsunami.
Why tsunamis are so dangerous
2.1 Tsunamis can come quickly with little warning they can't be seen until they hit shore with a powerful force. Locally generated tsunami may reach a nearby shore in less than ten minutes due to their high speeds therefore there might not be enough time for the Pacific Tsunami Warning Centre or for local authorities to issue a warning. Dangerous waves often follow the first tsunami wave, trapping people who return, thinking the tsunami is over. 3. How earthquakes form
Most earthquakes occur due to movement tectonic plates these are massive slabs of rock floating on magma ,as the These plates are in continuous movement. This movement eventually causes collision among the plates. Stress builds up on the lithosphere. This stress causes a break or shift in the crust. When the stress is released the energy starts moving from one place to another in the form of waves (called seismic waves). These waves shake the earth and causes an earthquake. Sometimes the stress occurs near the centre of the plate, but mostly it occurs on the edges. Here two plates collide or goes over or into another plate. This causes different types of earthquakes of different magnitudes....
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