Earthquakes, in the simplest way possible, are defined to be the shaking of the earth’s crust. This phenomenon occurs when the earth’s stored energy is suddenly released causing the emission of seismic waves. Physically, it is characterized by the ground’s displacement, often causing cracks on the soil, floor, concrete, or pavement on the affected areas. It can strike strong leading to massive property destruction and even death.
Earthquakes can be caused by nature or through human intervention. Another natural catastrophe, the tsunami, can be the reason for earthquakes. Human activities like oil drilling and deep excavations can cause earthquakes as well. Earthquakes can come in different intensities. Different devices, the most popular of which is the Ritcher Scale, is devised to measure its strength.
A deeper study on the components, environments, elements, and times of earthquakes are going to be discussed in this paper. Along with that, its linkages and interactions with other Earth systems are going to be analyzed. It is the objective of this paper to guide the readers into a conclusion as to what earthquake is, what it can do, and to what extent the researches about it can affect its occurrence.
- Earthquakes in its Contextual Form
Robert W. Day regarded that the formulation of the theory of plate tectonics in the year 1960 had helped immensely in the study and the understanding of earthquakes. According to this theory, the surface of the earth contains tectonic plates, which is also otherwise known as lithosphere plates. Tectonic plates are what consists the crust and the more rigid part of the earth’s upper mantle. These tectonic plates move following a relative direction. The locations of the great majority of earthquakes correspond to the boundaries between the plates. There are three types of plate boundaries, and these are the transform boundary, convergent boundary, and divergent boundary (Day 2002).
Transform plate boundaries forms when two plates slide horizontally past each other as they move in opposite directions. Frequent earthquakes are noted to occur along transform plate boundaries. This type of boundary is seen in both oceans and continents. An example of a transform plate boundary is the California’s San Andreas Fault. The fault is a transform boundary between the Pacific plate and the North American plate.
Thompson and Turk defined and described convergent boundaries to be lithospheric plates moving toward one another. Convergent boundaries are composed of the upper rigid portion of the mantle and topped by either the dense basaltic oceanic crust or the lighter granitic continental crust. There are three types of convergence boundaries: the ocean-ocean plate convergence, ocean-continent convergence, and continent-continent convergence.
Ocean-ocean plate convergence mostly occurs throughout the margins of the northern and western Pacific Ocean, where the Pacific Ocean plate, moving northwestward, collides with the oceanic crust of Eurasian and North American plates. When plate convergences of this type moves, the older, which is also the cooler and the denser plate descends below the younger and more buoyant ocean plate. In the example stated above, the Pacific Plate slides under the Eurasian and North American lithospheric plates and descends into the semi-plastic asthenosphere.
On the other hand, when an oceanic plate converges with a continental plate, the denser oceanic plate sinks into the mantle below the edge of the continent. As a result, many subduction zones are located at continental margins. Ocean-continent convergence plates are found beneath the western edge of South America and along the coasts of British Columbia, Oregon, and Washington.
If two converging plates carry continents, neither can sink deeply into the mantle due to their low densities. A continent does not normally sink into the mantle at a subduction zone. Both are of lower density than the material beneath them. In this case, the two continents collide and crumple against each other, forming a huge mountain chain. Examples of continent-continent convergence plates are the Appalachians, the Alps, and the Himalayas (Thompson & Turk 2005).
Divergent plate boundaries are also called spreading zones and rift zones. This occurs in the middle of ocean basins or in the middle of continents. Divergent basins are found in ocean basins. Davis and Firtzgerald gives the Pangaea as the best example of diverging plates, which was formed and had broken 200 million years ago (Davis & Fitzgerald 2004).
III. The Earth Systems and Earthquakes
Tides are part of the earth’s natural processes, and they can cause earthquakes. Tides are produced by the combined pull of both the Moon and the Sun. When both the Moon and the sun are positioned at a right angle, they produced small tides. Large tides are produced if the sun and the moon are in line. The strength of the large tides may cause horizontal compression. And these add to the natural drift of the tectonic plates. The result is the crumpling of the earth’s crust.
And quite naturally so, volcanic activities cause earthquakes. More particularly, volcanic eruptions can result to seismic disturbances. According to Glabsy, researches have it that volcanic eruptions leading to earthquakes can be caused by interplanetary alignments, more particularly when more than two planets are at nearly 90 degrees apart. This alignment stimulates the core, making the magma hotter (Glasby 2002).
Glasby also researched that the Earth’s gravity, as well as its electromagnetic forces, can trigger earthquakes also. The earthquake in the Los Angeles area, with a magnitude of 6.0 on the Ritcher scale, was forecasted because of the presence of unusually low electrical surges two weeks before the earthquake occurred. It was further found out that the ionosphere consists of charged particles in a radioactive state. The effect of the electromagnetic wave radiation may perhaps be somewhat similar to the effect in the core of the earth (Glasby 2002).
After describing the earthquake and the natural Earth systems that can trigger it, it can be concluded, without a hint of a doubt, that earthquakes do occur naturally. Something colossal like the movements of the planets causes earthquakes and that alone cannot be directly remedied with all the high technologies that are known to man today.
But even if that’s the case, earthquakes should still be controlled, if not duly regulated, no matter how natural a catastrophe it is. Today’s challenge is to devise a way to help the populace from being the sorry victims of a highly powerful force such as an earthquake. A good prediction device is going to be a feasible solution for now, but there should be an optimum discovery, today or in the future, that would undeniably control, if not hinder altogether, the occurrence of earthquakes.
Davis, R. A. & Fitzgerald D. M. (2004). Beaches and Coasts. Australia: Blackwell Publishing.
Day, R. W. (2002). Geotechnical Earthquake Engineering Handbook. New York: 2002.
Glasby, F. (2002). Planets, Sunspots and Earthquakes: Effects on the Sun, the Earth and Its Inhabitants. Nebraska: 2002.
Thompson, G. R. & Turk, J. (2005). Earth Science and the Environment. California: Thompson Brooks/Cole.