Definition of Earthquake
An Earthquake also known as tremor or quake, an Earthquake is the behavior by the earth’s surface blocks to suddenly slide past one another casing tearing of the blocks. The plane from which the block slides from is refferred to as fault plane. The position that is below the earhs surface where the earthquake originated is referred to as the hypocenter and the position that is directly above the hypocenter on the earth’s surface is referred to as the epic center (Green & Burnley, 1989).
Scientifically an earthquake is defined as production of seismic waves because of the abrupt ejection of energy from the earth’s crust. These seismic waves are measured using the seismograph (seismometer) (Bolt,1999). Seismometers contain the base that is firmly attached to the ground and a bulky weight that is loosely hanging. When the ground shakes, the base that is attached to the ground is the one, which is shaken while the loosely suspended weight is not moved. The difference of the shaken base and the loosely hanging weight is what is called the intensity of the earthquake and it depends on where you are during the earthquake (Watson, & Kathie, 1998).
Scientists are also concerned with assessing the magnitude of the earthquake. Since measuring the earthquakes depends on measuring the fault size and the extent of the slip, the measuring tape is inadequate to do this job. Hence, they depend on the seismographs produced by the seismometer in order to measure the size of the earthquake. The length of the wiggle lines is the measure of the amount of fault slip. If the wiggle lines are very small, it means the size of the fault is small. The size of the earthquake is measured in (Richter, moment) magnitude (Talebian & Jackson, 2004).
Cause the Earth to quake and shake
The earth is made up of four layers: the crust (outer most) followed by the mantle, and then the outer core and the inner core (the innermost part.).The crust is further made up of many pieces called the tectonic plates, which are always in motion sliding past each other or sometimes colliding. The edges of these tectonic plates are called plate boundaries and they are always rough.
The tectonic earthquake is the common earthquake that results from plate boundaries colliding on each other because of their rough edges; they are stuck on each other while the other part of the plate keeps moving causing frictional force. Once this frictional force is beyond the critical value, it can result to violent dislodgement of earth’s crust, which is as result of sudden failure at the fault. This result in the discharge of the elastic strain energy thus, seismic waves are emitted (Watson, & Kathie, 1998).
Two types of body waves an earthquake creates
It is common for earthquakes to generate seismic waves that adjust the shape of the rocks. On the earth surface, these two waves are S (shear) or P (push) waves.
The P waves are known to move very fast than the S waves. The P waves are similar to lightening whilst the S waves are equated to the thunder. During rainy weather, you could see the lightening first before you could hear the sound. Since light travels faster than the sound. This case also applies to the P and S waves depending the distance you are. P waves shake the ground where you are and rather the S wave comes rather depending your distance from the epic center (Green & Burnley, 1989).
The S wave moves inside the rocks they cause neither compression nor expansion on the rock but it does make the rock to resonate perpendicularly on their static place. A behavior likened when you perpendicularly shake a rope that is tied at one end. This kind of motion is called the shearing motion. The P waves have the ability to cause horizontal expansion and contraction in rocks. They have a potential to move the rocks from their original place (Watson, & Kathie, 1998).
The S Waves are known to penetrate through the solids and not in liquids since liquids does not have shear strength compared to P waves, which have a potential travel through both in solids and liquids (Talebian & Jackson, 2004)
Conclusion
From the above analysis, it can be concluded that the Earthquake can cause the earth to move horizontally because of shear waves or move perpendicularly depending of the type of wave. This result to divergent borders, convergent borders and transform fault borders (Talebian & Jackson, 2004).
Transform fault boundary, which is also referred to as thrust fault transpires when the block glides or drudges past each other down a transform line. The motion of the plates can be either Sinatra or dextral. Divergent boundaries occurs when two plates slid past each other and lastly convergent boundaries also called active margin it occurs when one plate moves below another or moving on top of another plate.
References
Bolt, B. A. (1999). Earthquakes. Boston, MA: W. H. Freeman.
Greene, H. W., Burnley, P. C. (1989). “A new self-organizing mechanism for deep-focus earthquakes”. Nature 341: 733–737.
Talebian, M., Jackson, J. (2004). “A reappraisal of earthquake focal mechanisms and active shortening in the Zagros mountains of Iran”. Geophysical Journal International.
Watson, John., Kathie P. (1998). “Volcanoes and Earthquakes”. United States Geological Survey. Web.