Earthquakes are tremors that result from abrupt release of energy in the earths crusts creating seismic waves. They can occur as a result of natural phenomena or human activities. They mostly result from rapture of geological vaults. Earthquakes usually manifest themselves by shaking and displacing the ground. The seabed suffers sufficient displacement to cause a tsunami when large earthquakes are located offshore. Shaking and displacement of the ground may trigger land slides as well as volcanic activities. Earthquakes are recorded using seismometer and are measured using the Richter scale.
The process, and examples of recent earthquakes and their consequences
Naturally occurring earthquakes are referred to as tectonic earthquakes. They occur on the surface of the earth where stored elastic strain energy is enough to drive fissure transmission along a fault plane. Convergent plate boundaries move past each other with ease and aseismically in case there are no irregularities to cause an increase in frictional resistance. Due to the fact that most boundaries do not have irregularities, a stick-slip behavior is produced. After the border lines have locked, further relative motion in between the plates leads to an increase in stress as well as stored strain energy volume around the surface of the fault (Burande, 2007).
This process goes on until the stress has increased adequately to break the irregularities. This breaking of the irregularities allows for sliding over the locked portion of the fault. As a result, the stored energy is released as a combination of radiated elastic strain seismic waves, cracking of the rock, and heating of the surface of the fault due to friction force, thereby causing an earthquake. Gradual build up of strain and stress may occur and be disrupted by abrupt earthquake failure, a phenomenon referred to as elastic rebound theory. Approximately ten percent or less of all the energy generated before an earthquake is radiated as seismic energy. Most of the energy is either used to propel the earthquake separation plane growth or transformed into heat produced by friction. Earthquakes lower the available elastic potential energy of the earth, but increase its temperature (University of Michigan, 2005).
Majority of naturally occurring earthquakes occur at a depth not exceeding tens of kilometers and originate from the ring of fire. Those that occur at a depth of less than seventy kilometers are referred to as shallow-focus earthquakes whereas those that occur at depths of between 70 and 300 are referred to as mid-focus earth quakes. Earthquakes that occur at depths of more than 300 kilometers are referred to as deep focus (Lechliter, and Willis, 1996).
The aftermath of earthquakes are experienced in a large area close to the epicenter. Faults that extend to the surface of the ground are the major cause of its cracking. Horizontal, as well as vertical dislocations of several areas occur. The range of earthquake vibration and its subsequent damage of an area are determined by the nature of the ground. In poorly compacted areas, vibrations have more amplitude and tend to last longer. Buildings and other structures found in urban areas which are densely populated do not have the capability of bearing the tremendous shaking and therefore undergo enormous destruction. L-waves can generate destructive vibrations in structures as well as buildings leading to uncontrollable fires (University of Michigan, 2005).
One of the most recent earthquakes in the United States is the earthquake in Haiti. The earthquake left the island totally destroyed. The small town of Haiti was reduced to rubles. It also caused the death of more than 200,000 people. All buildings in the island were totally destroyed. Millions of those who were left behind by the earthquake are without food and shelter (Baxamusa, 2010). Another recent earthquake is the Eureka earthquake which occurred in January this year in California. Though there were no major injuries reported, the earthquake destroyed several structures, shattered windows and severed power for several hours.
Inglewood earthquake is also an example of a recent earthquake. It occurred in the year 2009 in south California. This quake left a lot of windows shattered (Napach, 1998). Chino hills earthquake is another earthquake that occurred recently. It did not cause any death, but adversely damaged the region of the epicenter. The earthquake did not damage the infrastructure severely since most of it is relatively new and well suited to bear up a large quake. Some of the most seismically active regions in the world are found in California. It has got numerous faults that crisscross the state and lie on top of the worlds major tectonic plates that is Pacific and North American tectonic plates. Thousands of earthquakes hit south of California annually, but are too insignificant to be detected (Tornese, and Lawson, 1997).
Sudden release of energy in the earths crust creating seismic waves causes earthquakes. Earthquakes can either be caused by natural phenomenon or human activities. They manifest themselves by shaking and displacing the ground. Earthquakes are measured by the Richter scale and recorded using a seismometer. The development of an earthquake follows a characteristic process. Extensive stress on the outer layer of the earth pushes the sides of the earths fault together. The surface of the rock and the faults display a very high friction force that holds them from moving side ways initially. Enough stress finally builds up and the rocks slip abruptly. This slipping causes energy to be released in form of waves traveling through the rocks causing the ground to shake vigorously. The earthquake in Haiti is one of the most recent and adverse earthquake that have occurred in the United States. This earthquake have totally destroyed infrastructure and caused the death of thousands of people.
The process, and examples of recent earthquakes and their consequences
Naturally occurring earthquakes are referred to as tectonic earthquakes. They occur on the surface of the earth where stored elastic strain energy is enough to drive fissure transmission along a fault plane. Convergent plate boundaries move past each other with ease and aseismically in case there are no irregularities to cause an increase in frictional resistance. Due to the fact that most boundaries do not have irregularities, a stick-slip behavior is produced. After the border lines have locked, further relative motion in between the plates leads to an increase in stress as well as stored strain energy volume around the surface of the fault (Burande, 2007).
This process goes on until the stress has increased adequately to break the irregularities. This breaking of the irregularities allows for sliding over the locked portion of the fault. As a result, the stored energy is released as a combination of radiated elastic strain seismic waves, cracking of the rock, and heating of the surface of the fault due to friction force, thereby causing an earthquake. Gradual build up of strain and stress may occur and be disrupted by abrupt earthquake failure, a phenomenon referred to as elastic rebound theory. Approximately ten percent or less of all the energy generated before an earthquake is radiated as seismic energy. Most of the energy is either used to propel the earthquake separation plane growth or transformed into heat produced by friction. Earthquakes lower the available elastic potential energy of the earth, but increase its temperature (University of Michigan, 2005).
Majority of naturally occurring earthquakes occur at a depth not exceeding tens of kilometers and originate from the ring of fire. Those that occur at a depth of less than seventy kilometers are referred to as shallow-focus earthquakes whereas those that occur at depths of between 70 and 300 are referred to as mid-focus earth quakes. Earthquakes that occur at depths of more than 300 kilometers are referred to as deep focus (Lechliter, and Willis, 1996).
The aftermath of earthquakes are experienced in a large area close to the epicenter. Faults that extend to the surface of the ground are the major cause of its cracking. Horizontal, as well as vertical dislocations of several areas occur. The range of earthquake vibration and its subsequent damage of an area are determined by the nature of the ground. In poorly compacted areas, vibrations have more amplitude and tend to last longer. Buildings and other structures found in urban areas which are densely populated do not have the capability of bearing the tremendous shaking and therefore undergo enormous destruction. L-waves can generate destructive vibrations in structures as well as buildings leading to uncontrollable fires (University of Michigan, 2005).
One of the most recent earthquakes in the United States is the earthquake in Haiti. The earthquake left the island totally destroyed. The small town of Haiti was reduced to rubles. It also caused the death of more than 200,000 people. All buildings in the island were totally destroyed. Millions of those who were left behind by the earthquake are without food and shelter (Baxamusa, 2010). Another recent earthquake is the Eureka earthquake which occurred in January this year in California. Though there were no major injuries reported, the earthquake destroyed several structures, shattered windows and severed power for several hours.
Inglewood earthquake is also an example of a recent earthquake. It occurred in the year 2009 in south California. This quake left a lot of windows shattered (Napach, 1998). Chino hills earthquake is another earthquake that occurred recently. It did not cause any death, but adversely damaged the region of the epicenter. The earthquake did not damage the infrastructure severely since most of it is relatively new and well suited to bear up a large quake. Some of the most seismically active regions in the world are found in California. It has got numerous faults that crisscross the state and lie on top of the worlds major tectonic plates that is Pacific and North American tectonic plates. Thousands of earthquakes hit south of California annually, but are too insignificant to be detected (Tornese, and Lawson, 1997).
Sudden release of energy in the earths crust creating seismic waves causes earthquakes. Earthquakes can either be caused by natural phenomenon or human activities. They manifest themselves by shaking and displacing the ground. Earthquakes are measured by the Richter scale and recorded using a seismometer. The development of an earthquake follows a characteristic process. Extensive stress on the outer layer of the earth pushes the sides of the earths fault together. The surface of the rock and the faults display a very high friction force that holds them from moving side ways initially. Enough stress finally builds up and the rocks slip abruptly. This slipping causes energy to be released in form of waves traveling through the rocks causing the ground to shake vigorously. The earthquake in Haiti is one of the most recent and adverse earthquake that have occurred in the United States. This earthquake have totally destroyed infrastructure and caused the death of thousands of people.
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