Cause of an Earthquake
Earthquakes form when rocks break and slide quickly past each
other along large fault lines.
The fast movement of these plates
causes the ground below to shake which
is what happens during an
earthquake.
This motion occurs roughly 40 miles below the earth's surface, or at the focus. Waves branch out from the focus, which
causes tremors miles away. There are three types of surface waves. The primary waves take around twenty minutes to reach their
destination. That is called compressional. Transverse are the second form of waves. They move at a slower pace and take twice as long to reach the same place as primary waves. Movement is faster in dense, rigid rock and slower in lighter liquid materials like the
atmosphere.
Differences in the state of matter from layer to layer affect the behavior of waves. Waves are also influenced by the kind of boundary the plates
lie on. The theory of today is that of plate tectonics. Plate Tectonics was unbelievable when it first emerged and wasn't popularized until the 1960s. Previous to this theory was that of Continental Drift. It is believed that there are seven major plates that are in a continuous slow movement.
Plates
The plates come in contact with each other and it creates a lot of pressure. The pressure will eventually cause transduction where one plate will go above or below a the other plate. Plates can pull apart by moving away from each other, they can move close together, or they can move in
opposite directions. Scientists believe that mostly earthquake occurs due to the movement of plates and this theory is
known as plate tectonics.
This says earth outer crust has ten rigid, hard and large plates, twenty small plates. These plates are continuously moving on the hot and soft rock of mantle slowly. This movement causes collision among other plates which further causes stress on the lithosphere. The stress becomes enough to shift or break crust.Now the stress is released and this released energy starts moving from one place to another in the form of waves called seismic waves and these waves shake the earth which we named as earthquake. Sometimes this stress occurs near the centre of plate but mostly it occurs on the edges when two plates collide and goes over or into the plate. So by this different
types of earthquake of different magnitudes are caused. Stress in the earth's outer layer cause a pushing effect against the sides of the fault. Due to this motion, rocks slip or collide against each other releasing energy. This released energy travels in waves through the earth's crust and causes the shaking that we feel during an earthquake. Under the surface of the earth, the two sides of a fault are constantly moving, relative to one another. This movement is known as a fault slip. The movement of these two sides is not smooth and is accompanied
by a gradual build-up of elastic strain energy within the rocks along the fault.
Eventually, the strain along the fault becomes too much. The fault then ruptures with a sudden movement releasing all the energy it has built up. This energy is released in the form of vibrations called 'seismic waves'. These waves travel along the surface and through the earth at varying speeds depending on the material through which they move. It is actually these seismic waves that cause most of the destructive effects, which we associate with earthquakes.The location on a fault where the slip first occurs is called the hypocentre, whereas the position directly above it on the ground surface is called the epicentre. When these seismic waves reach the surface of the earth, they give rise to strong ground motion causing building and other man-made structures to shake or collapse or develop cracks and fissures. Earthquakes can also cause landslides, sudden eruptions as in the case of a hot lava flow from a volcano or giant waves called tsunamis. Sometimes new land mass are also
formed.
opposite directions. Scientists believe that mostly earthquake occurs due to the movement of plates and this theory is
known as plate tectonics.
This says earth outer crust has ten rigid, hard and large plates, twenty small plates. These plates are continuously moving on the hot and soft rock of mantle slowly. This movement causes collision among other plates which further causes stress on the lithosphere. The stress becomes enough to shift or break crust.Now the stress is released and this released energy starts moving from one place to another in the form of waves called seismic waves and these waves shake the earth which we named as earthquake. Sometimes this stress occurs near the centre of plate but mostly it occurs on the edges when two plates collide and goes over or into the plate. So by this different
types of earthquake of different magnitudes are caused. Stress in the earth's outer layer cause a pushing effect against the sides of the fault. Due to this motion, rocks slip or collide against each other releasing energy. This released energy travels in waves through the earth's crust and causes the shaking that we feel during an earthquake. Under the surface of the earth, the two sides of a fault are constantly moving, relative to one another. This movement is known as a fault slip. The movement of these two sides is not smooth and is accompanied
by a gradual build-up of elastic strain energy within the rocks along the fault.
Eventually, the strain along the fault becomes too much. The fault then ruptures with a sudden movement releasing all the energy it has built up. This energy is released in the form of vibrations called 'seismic waves'. These waves travel along the surface and through the earth at varying speeds depending on the material through which they move. It is actually these seismic waves that cause most of the destructive effects, which we associate with earthquakes.The location on a fault where the slip first occurs is called the hypocentre, whereas the position directly above it on the ground surface is called the epicentre. When these seismic waves reach the surface of the earth, they give rise to strong ground motion causing building and other man-made structures to shake or collapse or develop cracks and fissures. Earthquakes can also cause landslides, sudden eruptions as in the case of a hot lava flow from a volcano or giant waves called tsunamis. Sometimes new land mass are also
formed.