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Tectonic plates play an invaluable and crucial role in explaining why earthquakes occur. The planet is divided into numerous plates that neighbour each other, making up the geological planet, as we know it. These tectonic are continuously moving, and have, since the beginning of time. Our planet is tirelessly moving, from the beginning of time to the end of it. These tectonic plates are integrally involved with the occurrence of earthquakes. The earth's outer shell is known as the lithosphere. Tectonic plates are the outer shells of the Earth, that comprise the crust of it, and float on the liquid magma of the mantle beneath the crust. These plates are next to each other and make up the geological planet of Earth. Where these plates meet are where most earthquake activity occurs.
The location where tectonic plates meet are called plate boundaries. These play an important role in how earthquakes occur. The movement of these plates at their boundaries allow for movement above the ground on the surface, causing tremors, which vary in damage - which we now call earthquakes. Earthquakes are caused when violent vibrations occur, as a result of the release of energy in the Earth's crust. When this happens, the ground above the point where it occurs, shakes violently, causing structural damage and loss of life. The point underneath the Earth's surface where the sudden movement of plate occur is called the focus whilst the point directly above the focus, on the Earth's surface where the energy radiated from, is called epicentre. Surrounding plate boundaries are fault lines, areas where there is weakness and breaking of rock. The shallower the focus of earthquakes, that is, the closer the focus is to the surface, the more destructive an earthquake will be.
When plates are moving sideways and slide against each other, they build up stress and pressure. When the amount of pressure equates to a critical value, the two plates can no longer bear each other and they cannot handle the pressure and release the pressure, in the form of shock waves, that resonate upwards onto the surface of the Earth, where the tremors can be felt and mass destruction can occur. Earthquake energy is released in seismic waves. These waves spread from the focus outwards and is most strongly felt at the epicenter. As the waves travel away from the epicenter, they become less strong. The picture on the right shows a very simple diagram that depicts how earthquakes occur. The waves that are radiated from the focus travel as two different forms of waves, P-waves and S-waves.
These two waves differ in the way that they move. P-waves, or primary waves, are the first to reach the detector. These waves are longitudinal, which means that they vibrate along the same direction as the direction that the wave is travelling. P-waves behave in the same way that a stretched spring behaves. P-waves can travel through both solids and liquids. P-waves are the fastest types of seismic waves. The other type of wave is the S-wave, or secondary wave, which arrives second at the earthquake detector and are slower than p-waves. They travel in transverse waves, meaning that they travel at right angles to the direction of travel. Unlike P-waves, s-waves can only travel through liquids. The importance in these two waves is that they help geologists decipher how powerful the earthquake can be, by looking at the types of waves that radiate from the focus. Furthermore, the only type of energy released from earthquakes is that of p and s waves. The picture below shows primary and secondary waves.
P-waves and s-waves are known as body waves, but there are two other types of seismic waves that travel only through the crust of the earth, making it closer to the surface, hence, giving the name, surface waves. These waves are easily detected on seismographs. Love waves are the fastest surface waves and move from side to side, and produce entirely horizontal motion. The other type of surface wave is known as the Rayleigh Wave. Rayleigh waves a peculiar as they roll along the ground, just like an oceanic wave. Through rolling, all land top, bottom, right and left, of the wave moves. Rayleigh waves cause most of the shaking that is felt during an earthquake. Surface waves, though playing a less crucial role in earthquakes, are most felt during an earthquake, because of their proximity to the surface of the Earth, in comparison to S and P-waves.
The location where tectonic plates meet are called plate boundaries. These play an important role in how earthquakes occur. The movement of these plates at their boundaries allow for movement above the ground on the surface, causing tremors, which vary in damage - which we now call earthquakes. Earthquakes are caused when violent vibrations occur, as a result of the release of energy in the Earth's crust. When this happens, the ground above the point where it occurs, shakes violently, causing structural damage and loss of life. The point underneath the Earth's surface where the sudden movement of plate occur is called the focus whilst the point directly above the focus, on the Earth's surface where the energy radiated from, is called epicentre. Surrounding plate boundaries are fault lines, areas where there is weakness and breaking of rock. The shallower the focus of earthquakes, that is, the closer the focus is to the surface, the more destructive an earthquake will be.
When plates are moving sideways and slide against each other, they build up stress and pressure. When the amount of pressure equates to a critical value, the two plates can no longer bear each other and they cannot handle the pressure and release the pressure, in the form of shock waves, that resonate upwards onto the surface of the Earth, where the tremors can be felt and mass destruction can occur. Earthquake energy is released in seismic waves. These waves spread from the focus outwards and is most strongly felt at the epicenter. As the waves travel away from the epicenter, they become less strong. The picture on the right shows a very simple diagram that depicts how earthquakes occur. The waves that are radiated from the focus travel as two different forms of waves, P-waves and S-waves.
These two waves differ in the way that they move. P-waves, or primary waves, are the first to reach the detector. These waves are longitudinal, which means that they vibrate along the same direction as the direction that the wave is travelling. P-waves behave in the same way that a stretched spring behaves. P-waves can travel through both solids and liquids. P-waves are the fastest types of seismic waves. The other type of wave is the S-wave, or secondary wave, which arrives second at the earthquake detector and are slower than p-waves. They travel in transverse waves, meaning that they travel at right angles to the direction of travel. Unlike P-waves, s-waves can only travel through liquids. The importance in these two waves is that they help geologists decipher how powerful the earthquake can be, by looking at the types of waves that radiate from the focus. Furthermore, the only type of energy released from earthquakes is that of p and s waves. The picture below shows primary and secondary waves.
P-waves and s-waves are known as body waves, but there are two other types of seismic waves that travel only through the crust of the earth, making it closer to the surface, hence, giving the name, surface waves. These waves are easily detected on seismographs. Love waves are the fastest surface waves and move from side to side, and produce entirely horizontal motion. The other type of surface wave is known as the Rayleigh Wave. Rayleigh waves a peculiar as they roll along the ground, just like an oceanic wave. Through rolling, all land top, bottom, right and left, of the wave moves. Rayleigh waves cause most of the shaking that is felt during an earthquake. Surface waves, though playing a less crucial role in earthquakes, are most felt during an earthquake, because of their proximity to the surface of the Earth, in comparison to S and P-waves.
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How earthquakes are measured
There are many ways in which earthquakes can be measured. Earthquakes are unpredictable, no scientific genius has ever discovered a way of predicting such a tyrannic force. When it hits, it strikes with such sublime damage, that lives are lost and property destroyed. The instrument that is used to measure earthquakes is known as the Richter Scale. The richter scale works by detecting tremors and classifying them into a group, which corresponds to a number. Each number shows that it the quake is 10 times more powerful than the number below it. This is known as magnitude. For example, an earthquake with a magnitude of 5 is 10 times as powerful as an earthquake with a magnitude of 4. Magnitudes play an important role in earthquake detection as they provide the key to knowing how destructive and dangerous an earthquake is. The rank of magnitude ascends, with 0.0 exhibiting the least amount of damage, and 10 causing unimaginable mass destruction and loss of life. The numbers in between show varying effects of earthquakes. From magnitude 1.0 to 4.0, not much damage is caused - objects may swing and fall off, but nothing will collapse and no one will die. From 4.0 to 6.0, weak houses can collapse and people may die, 6.0 onwards will turn the heads of everyone around the world. It will cause collapses of houses, colossal amounts of loss of life and cause the landscapes to change.
Another device that is used widely in detecting earthquakes is the seismograph. This instrument is a piece of paper, taped to a table, with a pen suspended in the air by a bar. When there is movement, the pen records it onto the piece of paper. The size of the lines drawn depend on the strength of the shock waves. The picture on the right shows what a seismograph looks like.
There are many ways in which earthquakes can be measured. Earthquakes are unpredictable, no scientific genius has ever discovered a way of predicting such a tyrannic force. When it hits, it strikes with such sublime damage, that lives are lost and property destroyed. The instrument that is used to measure earthquakes is known as the Richter Scale. The richter scale works by detecting tremors and classifying them into a group, which corresponds to a number. Each number shows that it the quake is 10 times more powerful than the number below it. This is known as magnitude. For example, an earthquake with a magnitude of 5 is 10 times as powerful as an earthquake with a magnitude of 4. Magnitudes play an important role in earthquake detection as they provide the key to knowing how destructive and dangerous an earthquake is. The rank of magnitude ascends, with 0.0 exhibiting the least amount of damage, and 10 causing unimaginable mass destruction and loss of life. The numbers in between show varying effects of earthquakes. From magnitude 1.0 to 4.0, not much damage is caused - objects may swing and fall off, but nothing will collapse and no one will die. From 4.0 to 6.0, weak houses can collapse and people may die, 6.0 onwards will turn the heads of everyone around the world. It will cause collapses of houses, colossal amounts of loss of life and cause the landscapes to change.
Another device that is used widely in detecting earthquakes is the seismograph. This instrument is a piece of paper, taped to a table, with a pen suspended in the air by a bar. When there is movement, the pen records it onto the piece of paper. The size of the lines drawn depend on the strength of the shock waves. The picture on the right shows what a seismograph looks like.