An earthquake of 7.7 magnitude hits Indonesia: How is it measured?
The island of Indonesia has been hit with an underwater earthquake today. Although the Indonesian authorities have set the magnitude of the quake at 7.5 on Richter scale, the United States Geological Survey measured it at 7.6, while the European-Mediterranean Seismological Centre has measured it at 7.7. While all three falls under the major category of earthquakes, there are other categories as well.
What is a Richter Scale?
A Richter scale is a logarithmic scale that is used to quantitatively measure the magnitude (size or energy released) of an earthquake. It was invented in 1935 by American seismologist duo, Charles F. Richter and Beno Gutenberg, and was named after the former.
As is known, an earthquake’s magnitude is measured by an instrument called seismograph that uses this Richter scale for its precise calculations. The magnitude is determined using the logarithm in which the amplitude (height) of the largest seismic wave of a particular earthquake is calibrated on the Richter scale determining its severity.
Types of earthquake magnitudes as per the Richter Scale
Originally the Richter Scale was invented to measure an earthquake of moderate magnitude (3 to 7). However, with modern technological advancements, Richter scale can measure earthquake magnitudes ranging below zero (negative magnitudes) to as high as 10. However, till date, no earthquake of more than 8.6 Richter (1960 Chile earthquake) has been measured. Here’s a low-down on seven kinds of magnitudes as determined by Richter scale, and what they really mean.
Micro earthquake: The magnitude of micro earthquakes ranges from less than 1.0 to 2.9 on the Richter scale. These are hardly ever felt by human beings. However, they do get recorded on regional seismographs. Around 100,000 micro level earthquakes happen every year.
Minor earthquake: The magnitude of minor earthquakes ranges from 3.0 to 3.9 on Richter scale. These are occasionally felt by many people. However, they cause zero damage. Around 12,000 to 100,000 minor earthquakes are recorded every year.
Light earthquake: The magnitude of light earthquakes ranges from 4.0 to 4.9 on Richter scale. These are felt by majority of people and cause minor damage like breaking of light-weight objects lying around. Around 2000 to 12,000 light earthquakes are recorded every year.
Moderate earthquake: These are the most common types of earthquakes and its magnitude ranges from 5.0 to 5.9 on Richter scale. These are felt by all people and cause minor injuries and some noticeable cracks on weak constructions. Around 200 to 2000 moderate earthquakes are recorded every year.
Strong earthquake: The magnitude of strong earthquakes ranges from 6.0 to 6.9 on Richter scale. These are significantly felt by both humans and animals and cause moderate damage and casualties in densely populated areas. Around 20 to 200 strong earthquakes are recorded every year.
Major earthquake: Today’s Indonesian earthquake falls under this category in which the magnitude ranges from 7.0 to 7.9 on Richter scale. Generally, this kind of earthquakes cause serious damage over widespread areas and lead to many losses of lives. Only a handful (3 to 20) of them are recorded every year.
Great/Severe earthquake: The magnitude of great or severe earthquakes is usually 8.0 or above on Richter scale. People hardly ever get the time or scope to feel such earthquakes as they lead to extensive damages as soon as they strike causing innumerable casualties, and demolishing highly developed modern-day cities. Fortunately, less than 3 great earthquakes are recorded every year.