News of earthquakes frequently hit headlines. Around the globe earthquakes are happening. Though this is natural phenomenon but increased frequency of earthquakes has raised many eyebrows. Earthquakes has become topic of debate. Lets know why earthquakes occur? What are main causes of earthquake?
Let us know about why earthquake occurs ?
Earth is mainly made up of four layers. Inner core, outer core, mantle and crust. The crust and upper mantle core are called lithosphere. Now this 50 km thick layer is divided into several sections which are called tectonic plates. That is, the upper surface of the Earth is made up of 7 tectonic plates. These plates are never stationary, they are constantly moving. When these plates move towards each other, they collide with each other. A large amount of energy is released due to their collision, due to which there is a stir in the area and this movement is called earthquake.
Types of Earthquake
There are different types of earthquakes that have been observed:
- Tectonic Earthquake: This is the most common form of earthquake. This is usually due to the movement of plates present in the earth’s crust, which are called tectonic plates.
- Volcanic Earthquake: This type of earthquake is less common as compared to tectonic earthquake. These types of earthquakes occur before or after the eruption of a volcano. It is usually caused by the release of magma from a volcano, which is pushed to the surface by rocks.
- Brief Earthquake: This type of earthquake occurs in underground mines. The main reason could be the pressure generated within the rocks.
- Explosive Earthquake: This type of earthquake is artificial in nature, meaning it is generated by man-made activities. High-density explosions on the ground, such as nuclear explosions, are the primary cause of explosive earthquakes.
Earthquake Vocabulary
- Seismology: It is the branch of geology concerned with the study of earthquakes.
- Seismic Waves: These are waves of energy caused by earthquakes that travel through the surface of the earth.
- Epicenter: This is the point on the surface of the ground which is closest to the focus.
- Focus or Hypocenter: The point where the seismic waves originate is below the surface of the earth which is called the focus of the earthquake.
- Seismograph: The instrument on which seismic waves are recorded is called a seismograph.
- Richter scale: An instrument used to measure the intensity of an earthquake.
- Markli Scale: This instrument is used to record the intensity of an earthquake.
- Types of Seismic Waves: There are 3 types of seismic waves i.e. primary waves, secondary waves and surface or long waves.
Know what is the meaning of earthquake center and intensity?
The epicenter of an earthquake is the place just below which the geological energy is released by the movement of the plates. Earthquake vibrations are high at this place. As the frequency of vibration goes away, its effect decreases. However, if there is an earthquake with a magnitude of 7 or more on the Richter scale, then the tremor is stronger within a radius of 40 km around. But it also depends on whether the seismic frequency is upward or in range. If the frequency of vibration is higher then less area will be affected.
How is the intensity of an earthquake measured and what is the scale of measurement?
Earthquakes are measured by the Richter scale. This is called the Richter Magnitude Test Scale. Earthquakes are measured on a scale from 1 to 9 on the Richter scale. An earthquake is measured from its epicenter. It measures the intensity of the energy released from inside the earth during an earthquake. This intensity gives an idea of the magnitude of the tremor of the earthquake.
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