Buy essay on Science of Earthquakes

Science of Earthquakes
In the current essay I would like to consider the science of earthquakes, in particular the aspect of physics of earthquakes. To begin with, it should be noted that earthquakes – is tremors and vibrations of the Earth’s surface due to natural causes (mainly by tectonic processes), or sometimes artificial processes (explosions, filling reservoirs, collapse of underground cavities mining, etc.). Also, small earthquakes may be caused by the rise of the lava during volcanic eruptions. As a matter of fact, each year on Earth is happen about one million earthquakes, but most of them are so minor, that they go unnoticed. In turn, really strong earthquake, which is capable to cause extensive damage, occurs on the planet about once in every two weeks. Of course, most of them falls on the ocean floor, and therefore is not accompanied by catastrophic consequences if an earthquake under the ocean goes without tsunami, according to Hiroo Kanamori (2008).
It should be mentioned that the cause of the earthquake is the rapid shift of the site as a whole, the Earth’s crust at the time of the plastic (brittle) deformation of elastically strained rocks in the earthquake. Most earthquakes occur near Earth’s surface. Sliding rocks along the fault initially prevents friction. As a consequence, the energy that causes motion accumulates in the form of elastic strain rocks. When the stress reaches a critical point in excess of the frictional force, sharp breaks rocks with their mutual displacement, the stored energy, with releasing causing the wave oscillations of the surface of the earth – quake. Earthquakes can also occur during crushing of rocks in the fold when the magnitude of the elastic stress exceeds the tensile strength of rocks, and they break up, forming a fault. Further, seismic waves generated by earthquakes propagate in all directions from the source like sound waves. The point at which rocks start shifting is called a focus – a center or hypocenter, in turn the point on the earth’s surface above the focus – is the epicenter of the earthquake. Shock waves spread in all directions from the source, the farther away their intensity decreases. As a fact, velocity of seismic waves can reach 5 miles per second according to Cargill Gilston Knott (2010).
According to experts, there are two main reasons of the difficulty of earthquake prediction. First is the lack of direct access to the depths, where earthquakes occur. Secondly, scientists do not really know what an earthquake is. It can be explained by the fact that currently, there is no any reasonable physical model of this phenomenon. It is believed that the cause of earthquakes is high tectonic stresses. This theory is interpreted by analogy with the usual destruction of a rock sample, only a vast quantity. However, studies on the destruction of rocks under pressure have shown that these stresses are much smaller than those, which are actually required for its intended destruction, so this theory can not explain the cause of such catastrophic effects of earthquakes in nature. Nowadays, the main focus of research of earthquakes lies in the tracking variations and the intensity of seismic processes in order to identify the instability mode. The dominant model remains a theoretical concept that earthquake is a critical phenomenon. Although it follows the randomness and unpredictability, but it has no alternative. In other words, the nature of earthquakes is still secret for humanity, according to Hiroo Kanamori (2008).
It is essential to note that even if the measurement accuracy and the physical-mathematical model of seismic process, which does not exist for today, made it possible with sufficient accuracy to determine the location and time of the earthquake, the magnitude of future earthquake would be unknown. As a fact, all models of seismicity, which reproduce the recurrence graph of earthquakes, or which contain a stochastic generator that creates these models in a dynamic chaos, described only in probabilistic terms. More explicitly, the source of stochasticity can be qualitatively described as follows. Let the spreading during an earthquake is coming to the front of fracture site strength. Depending on the magnitude of the earthquake, fracture site will be destroyed or not. For example, if the front will further damage, earthquake would be catastrophic, and if not, it will remain small. The outcome depends on the strength of the site: if it is below a certain threshold, the destruction goes under the first scenario, if higher – under the second. Moreover, it should be noted that there is a “butterfly effect”: a negligible difference in strength or stress leads to macroscopic effects that can not be predicted deterministically, since this difference is smaller than any measurement accuracy. Without any doubts, a prediction of where and when earthquake will be with unknown possibly and quite safe magnitude has no practical meaning, as opposed to calculating the probability that a major earthquake will occur in a certain place, according to Cargill Gilston Knott (2010).
It can be said that humanity has not learned yet how to effectively predict earthquakes. In particular, scientist can not create effective methods for measuring stress at great depths in the crust. Also, scientists did not develop a fairly universal signs of the onset of disasters, which can be used by law. The main task for further thorough study of the nature of earthquakes remains collection of scientific data about the physics of this phenomenon in order to create a universal physical-mathematical model of the earthquake. However, there is some progress in the prediction of medium earthquakes, which allow authorities to provide reasonable economical policy planning, land usage, as well as advanced preparation for the expected disaster. For example, Chinese scientists achieved some success in prediction of earthquakes. They rely on the analysis of animals’ behavior, who feels the approach of an earthquake. Although this method can not be considered as 100% reliable, it still allows warning people and, if necessary, evacuating them from certain territory, according to Hiroo Kanamori, Emily Brodsky (2004).
To sum it up I would like to say that earthquakes – is tremors and vibrations of the Earth’s surface due to natural causes, or sometimes artificial processes. The cause of the earthquake is the rapid shift of the site as a whole, the Earth’s crust at the time of the plastic deformation of elastically strained rocks in the earthquake. It should be noted the main reason of the difficulty of earthquake prediction is the lack of direct access to the depths where they occur. Moreover, nowadays, there is no universal physical-mathematical model of the earthquake, which allow scientist to understand and, consequently, predict the earthquake and its magnitude in certain area. In my opinion, it is closely connected with the lack of funding. As a fact, scientist needs to drill into the ground near the junction of lithospheric plates, and examine the processes occurring inside. I think that humanity should immediately take steps with the aim to study the nature of earthquakes and learn how effectively react and predict them. I am convinced that humanity should foresee the appearance of such tragedies as the recent tsunami in Japan, which had disastrous consequences for the country.

References
Cargill Gilston Knott (2010). The Physics of Earthquake Phenomena. Nabu Press. 308 pages.
Hiroo Kanamori (2008). Earthquake physics and real-time seismology. Nature 451, 271-273.