Types, Causes, effects of
Earthquake and Protection
An earthquake is one of the biggest natural disasters. Every year it causes huge loss of life and property around the world. Proper disaster management strategies and awareness are a must today. This will protect us from losses and help us cope with these dangers. However, to limit the destruction caused by these events, the Disaster Management Committee has laid down some safety measures.
Causes of earthquakes
Earthquakes are caused by sudden tectonic movements in the Earth's crust. Tectonic plates found in the ocean are called oceanic plates, while those found on continents are continental plates. The movement of these tectonic plates creates energy that can be released once these plates meet at a so-called fault line. The intensity of this released energy will also determine the earthquake's power. As energy is removed from the Earth's crust, we can feel the Earth shaking.
On several occasions, earthquakes have been predictions. Foreshocks are smaller versions of earthquakes occurring in the same area as more significant ones. Scientists have only been able to tell whether an earthquake is a prediction once an actual earthquake occurs. A natural or more significant earthquake is known as a mainshock. Mainshocks are, on many occasions, followed by an aftershock. Aftershocks are a collection of small earthquakes that occur after a main quake. Depending on the size of the mainshock, aftershocks can continue for weeks, months, or even years.
For an earthquake to occur, energy is released from the focal point. This point is called the epicenter and is usually located at shallow depths from the Earth's surface. Seismic waves are produced from the epicenter and sent out in all directions. Seismic waves then move at different speeds depending on the type of material they pass through.
Types of earthquakes
1. Tectonic earthquakes
The Earth's crust is made up of loose, cracked fragments of the Earth known as tectonic plates. These plates can move slowly and gradually. The movement of these plates occurs in various forms; towards each other, away from each other, sliding around each other, or bumping into each other. A colossal earthquake occurs when 2 moving tectonic plates slide past each other. This type of earthquake is known as a tectonic earthquake.
Tectonic earthquakes are the most widespread type of earthquake in the world. Its size can be small or large. Tectonic earthquakes caused most of the planet's mass destruction. The tremors caused by tectonic earthquakes are always strong, and if their magnitude is high, they are capable of destroying an entire city in seconds.
2. Volcanic earthquakes
Compared to tectonic earthquakes, volcanic earthquakes are less widespread. They usually take place before or after an eruption. Volcanic earthquakes come in two forms: long-duration volcanic earthquakes and volcano-tectonic earthquakes. Volcano-tectonic earthquakes typically occur after a volcanic eruption. During an earthquake, magma erupts from within the Earth's crust, leaving behind a space. The space left after the magma eruption must be filled. To fill it, rocks move toward the area, which leads to strong earthquakes.
On many occasions, magma blocks vents during volcanic activity. This means that the high pressure will not be released. The pressure build-up becomes unbearable and removes itself with a massive explosion—a massive explosion results in a ferocious earthquake.
On the other hand, a long period of volcanic earthquake occurs after a volcanic eruption. A few days before a massive explosion, the magma inside the Earth's crust experiences rapid heat changes. The change in heat triggers seismic waves that result in earthquakes.
3. Explosion Earthquake
Nuclear explosions cause these. They are man-made earthquakes and represent the most significant impact of modern nuclear warfare. During the 1930s of United States atomic tests, numerous small towns and villages were devastated by this grave act.
4. Collapse Earthquake
These types of earthquakes are generally smaller and often occur near underground mines. They are sometimes referred to as mine explosions. Collapse earthquakes are caused by pressure generated in rocks. This kind of earthquake causes the roof of the mine to collapse, triggering more tremors. Collapse earthquakes are prevalent in small towns where underground mines are located.
Devastating effects of earthquakes
1. Damage to buildings
A large-scale earthquake can lead to the complete collapse of buildings. Debris from collapsing buildings is a significant hazard during an earthquake, as the fall of huge, heavy objects can be fatal to humans. Large-scale earthquakes lead to broken mirrors and windows, which also harm humans.
2. Infrastructure damage
An earthquake can cause power lines to fall. This is dangerous because exposed live wires can electrocute people or cause fires. Large earthquakes can rupture roads, gas pipelines, and water pipes. A broken gas line can cause a gas leak. Leaking gas can cause explosions and fires that can be difficult to contain.
3. Landslides and rockslides
When an earthquake occurs, large rocks and chunks of Earth placed on a slope can be dislodged and rapidly roll down into the valley. Landslides and rockslides can cause destruction and death to people living downstream.
4. It May cause flooding
Large-scale earthquakes can cause dam walls to crack and collapse long-term. This would send raging waters into surrounding areas, leading to massive flooding.
5. Earthquakes can cause tsunamis
A tsunami is a series of long tremors in the open sea caused by earthquakes or volcanic eruptions under the sea. A tsunami can destroy the entire surrounding population of coastal areas. A typical example is the March 11, 2011 earthquake and tsunami that hit the coast of Japan and left more than 18,000 dead.
6. Leads to liquefaction
Liquefaction is a phenomenon where the soil becomes saturated and loses strength. When sediments with a high water content are subjected to continuous shaking, the water pressure in the sediment's pores slowly increases.
Eventually, the sediments lose almost all cohesion and behave like liquids. Buildings and other structures built on this liquefied soil topple over or sink into the ground. Earthquakes are responsible for most liquefaction occurring worldwide. A typical example of liquefaction phenomenon is the 1692 earthquake in Jamaica, which resulted in the devastation of Port Royal.