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Apr26 Fun Holiday – Richter Scale Day

April 26 is Richter Scale Day. The unofficial holiday honors the life and work of American seismologist Charles Francis Richter.

Seismograph for measuring tremors.

A seismograph measures the strength and magnitude of tremors on the Richters scale.


Born on this day in 1900, Richter was the inventor of the Richter magnitude scale that measures the intensity of earthquakes.

From 1935

Known more commonly as the Richter scale, the scale was invented by Richter in 1935. It measures the magnitude of an earthquake on a logarithmic scale of 0 to 10. Each number on the scale refers to an event that is 10 times more powerful than an event with a number before it. This means an earthquake with a magnitude of 4 is 10 times stronger, and releases approximately 32 times more energy, than an earthquake with a magnitude of 3.

Modern Replacements

The Richter scale has now been replaced by more modern scales that calculate the magnitude and strength of earthquakes around the world. Despite this, the media commonly, but mistakenly, uses the term Richter scale when identifying the device that measures earthquakes.

How to Celebrate?

  • Learn more about the Richter scale and how it is used to measure the intensity of earthquakes.
  • Visit your local space or science museum to learn more about earthquakes and what causes them.
  • If you live in an earthquake-prone area, why not use to the day to run some emergency earthquake drills and ensure that your emergency supplies are up to date and easily accessible?

Did You Know…

…that earthquakes lower than 2.5 on the Richter scale are almost never felt by humans?

Richter Scale Day Observances

Fun Holiday: Richter Scale Day Observances
2024FriApr 26Richter Scale Day
2025SatApr 26Richter Scale Day
2026SunApr 26Richter Scale Day
2027MonApr 26Richter Scale Day
2028WedApr 26Richter Scale Day
2029ThuApr 26Richter Scale Day
2030FriApr 26Richter Scale Day
2031SatApr 26Richter Scale Day
2032MonApr 26Richter Scale Day
2033TueApr 26Richter Scale Day

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