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Occurrence of Earthquake

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Occurrence of Earthquake: An earthquake refers to the sudden shaking of the surface of the earth, which results in the sudden release of energy in the lithosphere of the Earth, which leads to the creation of seismic waves. Earthquakes range variously in intensity and the seismic activity of an area has the frequency, type, and size of earthquakes which is experienced at a particular time.

Earthquake

Earthquake

Earthquake

An earthquake is the trembling of the earth’s surface caused by a rapid release of energy inside the earth’s crust. Seismic waves are produced as a result. The kind and severity of an earthquake are determined by seismic activity in the area. Earthquakes can range in strength from those that are so little that they are barely felt to those that are powerful enough to drive things and people into the air, damage essential infrastructure, and even devastate entire cities.

Seismic-Waves-and-Structure-of-the-Earth-1-(2)

Seismic Waves

When the epicenter of a large earthquake is situated offshore, the seabed which is present is displaced sufficiently for causing tsunamis and the earthquakes can also lead to landslides.

Magnitude of Earthquakes

An earthquake’s magnitude is a numerical scale that measures the amount of seismic energy released by it. Magnitude is the most commonly used measure to quantify the total strength or size of an earthquake. An earthquake’s magnitude is stated in decimal fractions and whole numbers.

 A 5.3 magnitude earthquake, for example, is regarded as mild, whereas a 6.3 magnitude earthquake is deemed powerful. Due to the logarithmic basis of scale, each whole number increase in magnitude corresponds to a tenfold increase in observed amplitude on a seismograph. In modern times, scientists and engineers utilize a variety of magnitude scales to estimate the relative size of an earthquake. An earthquake magnitude scale has no upper or lower bounds.

Earthquake Frequency

The frequency with which a certain magnitude earthquake occurs is commonly defined by an earthquake. On average, an earthquake of magnitude 2 or less occurs several hundred times per day around the planet. Every month, a large earthquake with a magnitude of 7.0 to 7.9 occurs somewhere in the world. An earthquake, on the other hand, happens once a year and has a magnitude of 8.0 or greater.

Occurrence of Earthquake

Earthquakes are triggered by abrupt tectonic upheavals in the earth’s crust. When tectonic plates contact, orogeny develops, resulting in earthquakes and volcanoes. As a result of these disturbances, vibrations spread in all directions. Tension is created when the plates move with respect to one another, which causes the plates to fracture by releasing the stored energy in the form of shock waves. This causes energy to be released, which travels in the form of energy waves in all directions. 

Most earthquakes happen along the tectonic plate boundaries and along the cracks in the lithosphere which are known as faults, or along mid-oceanic ridges but most of the seismic energy comes to be released in the earth from earthquakes that occur along plate boundaries, particularly around the Pacific Rim or Ring of Fire, where there is a particularly intense tectonic activity which causes Tsunamis at short intervals of time.

Ring of Fire

Ring of Fire

The epicenter, also known as the hypocenter, is the place at which the energy of an earthquake is released. On the earth’s surface, the epicenter is the point directly above the focus. It should be your first stop. As a result, earthquakes are often generated by the breaking of underlying rock along a fault line. This quick release of energy generates seismic waves, causing the ground to tremble. When two rocks or plates meet, they cling to one another in a specific way. An earthquake occurs when the rocks crack.

Causes of Earthquake

  1. Pore’s pressure reduction in groundwater
  2. Pore pressure rise in groundwater
  3. Heavy rainfall
  4. Unexpected tectonic shifts
  5. Constructing dams

Effects of Earthquake

  1. Human and animal death
  2. Several structures, lakes, and bridges are destroyed
  3. Tsunamis, landslides, and flooding
  4. A fire broke out, and dangerous substances got discharged.
  5. Breakdown of the Ground
  6. Ground collapse
  7. Land shaking

Instruments for Measuring Earthquake

Seismographs, the Richter Scale, and the Mercalli Scale are used for measuring the direction and intensity of earthquakes.

Seismograph

Equipment called a seismograph records the movement of waves and their passage at a specific spot. It is equipped with a pen. The pen vibrates in time with the seismic waves, capturing their motions on a moving strip of paper.

The Richter Scale

Charles F. Richter of the California Institute of Technology created the Richter scale in 1935 as a mathematical tool for comparing the size of earthquakes. The Richter scale ranks the strength of an earthquake from 1 to 9.

The Mercalli Scale

The Mercalli scale is a seismic scale that is used to determine the magnitude of an earthquake. The scale is now measured on a scale of 12 degrees of intensity, denoted by Roman numerals I to XII, based on observations and experiences. 

Earthquake Safety Information

Drop, Cover, and Hold on

In most cases, you may defend yourself immediately:

  1. Drop downward on your knees and hands
  2. Cover your head and neck
  3. Hold on to your place
  • During an earthquake, do not go outside or to other rooms.
  • You should not stand in a doorway. Under a table, you’re safer.
  • Drop, cover, and hold on if you are in a high-rise building.
  • Drop, cover, and hold on if you are inside a crowded area.
  • Drop, cover, and hold on until the shaking stops if you are near the shore.
  • Keep a safe distance from structures, power wires, sinkholes, and fuel and gas lines. 
  • Stop as quickly and safely as possible if you are in a moving car.

Related Articles

  1. Earthquake- Definition, Causes, Effects, Protection
  2. Causes of Earthquake
  3. Destructive and Constructive Effects of Earthquakes

FAQs on Occurrence of Earthquake

1. What is the occurrence of an earthquake?

The occurrence of an earthquake is due to stress on the edge for overcoming the friction, due to an earthquake the energy is released in the waves which travel through the crust of the earth and causes shaking.

2. Where are most earthquakes occurring?

Most earthquakes occur along the rim of the Pacific Ocean, where over 81 percent of the world’s earthquakes occur.

3. What is the occurrence of earthquakes along the fault?

The occurrence of earthquake along the faults is the strike-slip earthquakes which occur on the strike-slip faults, normal earthquakes occur on normal faults and thrust earthquakes happen along thrust faults.



Last Updated : 17 Jan, 2024
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