Free «Earthquakes and Volcanoes» Essay Sample

Earthquake

Earthquakes are some of the most destructive natural disasters. An earthquake consists of rapid vibration of the earth surface. Since its occurrence and enormous capacity is unpredictable by the ordinary human beings, it has been creating fear in human beings since the ancient times. A single shock would last for a few seconds, but when a series of smaller quakes occurs, it could last for about five minutes. It occurs quite frequently across the world but most of the times earthquakes are not very strong to be witnessed by people. However, huge earthquakes have devastating effects. This essay seeks to illustrate the causes and effects of earthquakes.

There are two types of earthquakes: tectonic and volcanic. Tectonic earthquakes occur when the earth is subjected to immense strain making it to eventually move. The earth crust comprises of several plates which float on the mantle. Considering that the plates can move, they can drift apart, towards each other, or slide against each other causing a subduction zone. According to Abrams & Morton (2007), convergent boundaries occur when too much pressure is generated between two plates over a long time. With time, one of the plates bends under the other due to extreme force. As much as the movement is too slow, pressure eventually builds up in the rocks. Eventually an earthquake happens when the pressure can no longer be held by the rocks. The fault ruptures causing the plates to move a long distance in a very short time. The collision triggers large forces in the plates resulting to the occurrence of earthquakes. The best example of a plate tectonic quake is that which occurred in the San Andreas Fault. In this case, the North American plate and the Pacific plate were moving towards the same direction but one was moving faster than the other.

On the other hand, the volcanic earthquakes are caused by the explosive volcanic eruption. This could either occur at the sea bed or on the land. There are many faults across the world. The location of such faults is a major determinant of where an earthquake will occur because they are the main causes of earthquakes. The type of the fault also determines how often earthquakes occur (Abrams & Morton, 2007). When the earth crust is submitted to tensional forces, it becomes thinner and weak. It causes a hot spot in the mantle which leads the magma to produce pressure and penetrate into the lithosphere and eventually erupt. Earthquakes are triggered by the forceful movement of magma as it finds its way onto the earth surface.

Earthquakes have various effects including damage to infrastructure, change in geological features and impact on the living things in the areas they occur. Rae (2008) asserts that the rumbling of the earth usually shakes tall buildings, dams and bridges making them fall down. These structures could fall on human beings and animals and kill them or affect the transport system. It becomes very difficult to transport the food, water and health aid to the affected people when bridges are destroyed.

They can also trigger geomorphologic changes. For instance, they could cause the earth crust to move either horizontally or vertically. This could cause a rising, tilting, or dropping of the earth surface and eventually causing landslides or floods. They could also damage gas and power lines and cause fires (Rae, 2008). Additionally, earthquakes that occur in the sea can cause tidal waves or tsunamis: Long and high walls of water travelling at a very high speed. Tsunamis can destroy an entire city or population living next to the coastline. They can also lead to various health effects such as the spread of waterborne diseases that end up killing human beings and animals.