Richter Scale

By Ismael Gba

The Richter Scale is the best known scale for measuring the magnitude of earthquakes. The magnitude value is proportional to the  strongest wave during an earthquake. A recording of 7, for example, indicates a disturbance with ground motion 10 times as large as a recording of 6. The energy released by an earthquake increases for every unit increase in the Richter scale. The table below gives the frequency of earthquakes and the effects of the earthquakes based on this scale. The biggest earthquake ever recorded was in Chile which hit the Richter scale 9.8.

 

Richter scale no.

No. of earthquakes per year

Typical effects of this magnitude

< 3.4

800 000

Detected only by seismometers

3.5 – 4.2

30 000

Just about noticeable indoors

4.3 – 4.8

4 800

Most people notice them, windows rattle.

4.9 – 5.4

1400

Everyone notices them, dishes may break, open doors swing.

5.5 – 6.1

500

Slight damage to buildings, plaster cracks, bricks fall.

6.2  6.9

100

Much damage to buildings: chimneys fall, houses move on foundations.

7.0 – 7.3

15

Serious damage: bridges twist, walls fracture, buildings may collapse.

7.4 – 7.9

4

Great damage, most buildings collapse.

> 8.0

One every 5 to 10 years

Total damage, surface waves seen, objects thrown in the air.

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