Introduction
It is surprising but there is something in common between two seemingly opposite geographical objects: the Himalaya and the Marianas Trench. The thing that connects the high mountain and the deepest trench in the world is their common origin: both of them are formed as the outcome of the same geologic process – the collision of the lithospheric plates (Plate Tectonics undated, p.90). The lithospheric plates can be characterized by the state of constant motion that influences the state of the Earth’s surface alternating our world constantly. Thus, the present paper is devoted to plates, plate margins and the process typical of them, mainly earthquakes that occur primarily along the margins of plates.
The movement of lithospheric plates
In the first place, it is necessary to determine the movement of the Earth, the plates’ movement in particular, when it quakes and shakes. The movement of the lithospheric plates is one of the key processes that determine the existence of the planet as we have an opportunity to witness it. There is a widely spread hypothesis that states that there existed a “single supercontinent, named Pangea” “around 250 million years ago” (Continents of the Past undated).
The movement of lithospheric plates explains its split and appearance of the present continents. Scientists define several possible ways of motion of plates in their relation to each other. The plates can be characterized by lateral motion, which is called translation, as it is stated in “Born of Fire”. The other ways of plates’ movement are as follows: subduction, which occurs when one lithospheric plate “descends into the mantle beneath another plate” (Plate Tectonics undated, p.104) and spreading (Born of Fire undated). In fact, the type of plate margins and the activity of faults determine the plates’ movement.
The causes of plates’ movement
In the second place, it is necessary to determine the causes of plate movement that are the driving forces of earthquakes. They are directly connected with the type of plate margins that are present on the territory where an earthquake occurs. An earthquake can occur if there is sufficient amount of elastic strain energy that is produced by the movement of the lithospheric plates. Due to this huge energy, a fracture that is called a fault is created. When the fault is locked, energy is building up more and it causes “rocks adjacent to the jammed section to bend and buckle” (Earthquakes and Earth’s Interior undated, p.118). The energy is released in the form of seismic waves that cause an earthquake.
The magnitude scales
Earthquakes can differ by the amount of seismic activity and the amount of energy that is released in the process. The Richter magnitude scale is the one that is commonly known. Its wide application is determined by the fact that this scale applies the objective data from seismographs instead of subjective data. Besides, the place of location of a seismic station does not influence that data gathered. This accounts for its wide usage. Thus, this magnitude scale is based on the amplitude of the seismic waves (Earthquakes and Earth’s Interior undated, p.132). There are also magnitude scales that are based on the amount of damage caused by an earthquake. An example can be the Modified Mercalli Intensity Scale (Earthquakes and Earth’s Interior undated, p.132).
The magnitude of an earthquake is usually determined today with the help of the Richter magnitude scale and moment magnitude. The latter is “based on the rupture size, rock properties, and amount of displacement on the fault surface” (Earthquakes and Earth’s Interior undated, p.132).
The types of body waves
As it has been mentioned above, seismic waves appear as the result of the release of energy in the process of earthquake. There are two types of waves that are produced while the earthquake occurs. They are body waves and surface waves. Body waves can be divided into two subtypes. The first type is compressional wave or P wave. Its main feature is that it has the highest velocity among seismic waves and is able to pass through solids, liquids, and gases (Earthquakes and Earth’s Interior undated, p.129).
Another type of body waves is called shear waves, which go through materials “by generating an undulating motion” in this material (Earthquakes and Earth’s Interior undated, p.129). In contrast to the first type of body waves, shear waves cannot go through liquids and gases. Besides, these waves are much slower than compressional waves. This accounts for another terms used in to denote them, S waves. To get at the essence of an S wave, it will be useful to resort to an example provided in the animation “Seismic Waves”, which says that an S wave is like “a rope being shaken up and down” (Seismic Waves undated).
The areas that are prone to earthquakes
To add practical character to the present paper, let us set some examples of the areas that are prone to earthquakes. On watching “Walk the Ring of Fire”, it is possible to state that such areas are as follows: Indonesia, the Philippines, which are characterized by the presence of subduction zones, Alaska, and Peru (Walk the Ring of Fire undated).
Conclusion
In a conclusion, it is necessary to state that earthquakes are among the most devastating natural catastrophes that take numerous lives and cause huge damage. As it can be seen in this paper, earthquakes are inevitable in the zones of high seismic activity and movement of lithospheric plates. Thus, scientists’ main task is to determine the time and place where an earthquake will occur to minimize its danger and the damage.
Reference List
Anonymous. (Undated). Plate Tectonics. National Geographic, 90-115.
Anonymous. (Undated). Earthquakes and Earth’s Interior. National Geographic, 116-149.
Born of Fire. Web.
Continents of the Past. Web.
Seismic Waves. Web.
Walk the Ring of Fire. Web.