Earthquakes and their Effects

An earthquake is a trembling or a shaking movement of the Earth's surface. The dictionary meaning of the word earthquake is “shaking and vibration at the surface of the earth resulting from underground movement along a fault plane of from volcanic activity”. The word earthquake is also widely used to indicate the source region itself. The solid earth is in slow but constant motion and earthquakes occur where the resulting stress exceeds the capacity of Earth materials to support it.

Earthquakes produce various damaging effects to the areas they act upon. This includes damage to buildings and in worst cases the loss of human life. The effects of the rumbling produced by earthquakes usually leads to the destruction of structures such as buildings, bridges, and dams. They can also trigger landslides. Earthquakes have varied effects, including changes in geologic features, damage to man-made structures, and impact on human and animal life.

Earthquakes often cause dramatic and geomorphological changes, including ground movements either vertical or horizontal along geologic fault traces, rising, dropping, and tilting of the ground surface, changes in the flow of groundwater.

Besides producing floods and destroying buildings, earthquakes that take place under the ocean can sometimes cause tsunamis, or tidal waves. Tsunamis are high and long walls of water which travel at a very rapid rate. They are notorious for destroying entire populations and cities near coastlines. In 1896 Sanriku, Japan, with a population of 20,000, suffered such a fate. Several thousand stations monitor earthquakes all over the world. Each station contains an instrument, called a seismograph, used to detect arrival times and record seismic waves.