A little reason to celebrate
National Richter Scale Day
History ยท April 26
A look at the Richter scale, the logarithmic measure of earthquake size, and how scientists describe the strength of a quake.
National Richter Scale Day falls on Monday, April 26, 2027. That is 181 days away.
The Richter scale is a way of putting a number on an earthquake. It was developed in California as a method for comparing the size of quakes using readings from a seismograph, the instrument that records how much the ground moves.
The scale is logarithmic, which is the part that surprises people. Each step up by one whole number means the recorded ground motion is ten times larger. So a quake rated 6 is not a little stronger than a 5. It is a different kind of event, and the energy released grows even faster than the shaking.
Today seismologists mostly use the moment magnitude scale for larger earthquakes, because it holds up better for very big quakes. News reports still often say "Richter scale" out of habit, and the numbers on the two scales are designed to line up fairly closely for moderate quakes. The name stuck long after the method was refined.
Marking the subject is mostly a matter of curiosity. You can look up recent earthquakes on public monitoring maps, which show small tremors happening somewhere almost all the time. Many science museums have seismographs on display, and some let visitors jump near a sensor to watch the needle or line respond.
It is also a quiet prompt to check a household earthquake kit if you live where the ground moves. Water, a flashlight and a sturdy pair of shoes by the bed cover a lot of ground, so to speak.
Ways to celebrate
- Look at a public earthquake map and count today's small tremors worldwide.
- Visit a science museum with a working seismograph on display.
- Explain to someone why a magnitude 6 dwarfs a magnitude 5.
- Check that your emergency kit has water, a flashlight and batteries.
Dates
| Year | Date |
|---|---|
| 2026 | Sunday, April 26 |
| 2027 | Monday, April 26 |
| 2028 | Wednesday, April 26 |
| 2029 | Thursday, April 26 |
| 2030 | Friday, April 26 |
Also on April 26
- National Pretzel Day
- National Help a Horse Day
- National Kids and Pets Day
- Alien Day
- Audubon Day
- National Static Cling Day
Categories: History days