Is the Richter Scale Obsolete?

Answers to your questions about the news.
March 1 2001 6:29 PM

Is the Richter Scale Obsolete?

The Seattle earthquake registered 6.8 on the ... well, not on the Richter scale, which the New York Times reported has been displaced. Is the Richter scale obsolete, and what is used instead?

Advertisement

While the Richter scale is not obsolete, the universal measurement today is the moment magnitude scale. The Richter scale was developed by seismologist Charles Richter (1900-1985) in the 1930s to bring consistent, objective criteria to evaluating the size of earthquakes. Richter, who worked in southern California, using data from seismographs--which measure earth movement--devised a method to calculate where an earthquake began, or its epicenter, and its magnitude. The way the scale works, each whole number increase, say from 4.8 to 5.8 to 6.8, represents a 10-fold increase in the size of the ground motion. As effective a tool as the Richter scale is, it has some drawbacks. For one, it is a relative measure; that is, it was developed to compare the size of one earthquake to another. But scientists wanted something that measured an earthquake not just in comparative terms, but in absolute terms. They wanted to get a physical snapshot of how much energy was released when a fault slipped. For another, although the Richter scale was revised to be used to measure earthquakes in other parts of the world, it had limitations since it was based on conditions in California. Scientists wanted a measurement that was universally applicable.

With the creation of more sophisticated seismology equipment in the 1970s, scientists could determine the actual area where the rupture in the fault took place and measure how much energy was released there during the earthquake, a calculation they call the seismic moment. Because the Richter scale had become so commonly understood, they devised a method to convert the information from the seismic moment into a scale comparable to Richter's, or what's now known as the moment magnitude scale. It is also possible to compare earthquakes using the new scale to those measured in the past on the Richter scale. Although the two scales may use different methods, they should end up producing virtually the same number.Many news organizations have dropped the "Richter" but not adopted the phrase "moment magnitude" scale. Instead the common shorthand is to describe an earthquake as being a "magnitude [fill in the number]."

Explainer thanks Paul Bodin and Gary Patterson of the University of Memphis. For more on earthquakes and their measurement, click here.

TODAY IN SLATE

Politics

The Democrats’ War at Home

How can the president’s party defend itself from the president’s foreign policy blunders?

The Religious Right Is Not Happy With Republicans  

The XX Factor
Oct. 1 2014 4:58 PM The Religious Right Is Not Happy With Republicans  

How Did the Royals Win Despite Bunting So Many Times? Bunting Is a Terrible Strategy.

Catacombs Where You Can Stroll Down Hallways Lined With Corpses

Homeland Is Good Again! For Now.

Crime

Operation Backbone

How White Boy Rick, a legendary Detroit cocaine dealer, helped the FBI uncover brazen police corruption.

Music

How Even an Old Hipster Can Age Gracefully

On their new albums, Leonard Cohen, Robert Plant, and Loudon Wainwright III show three ways.

The One Fact About Ebola That Should Calm You: It Spreads Slowly

Piper Kerman on Why She Dressed Like a Hitchcock Heroine for Her Prison Sentencing

Trending News Channel
Oct. 1 2014 1:25 PM Japanese Cheerleader Robots Balance and Roll Around on Balls
  News & Politics
Crime
Oct. 1 2014 4:15 PM The Trials of White Boy Rick A Detroit crime legend, the FBI, and the ugliness of the war on drugs.
  Business
Moneybox
Oct. 1 2014 2:16 PM Wall Street Tackles Chat Services, Shies Away From Diversity Issues 
  Life
Outward
Oct. 1 2014 6:02 PM Facebook Relaxes Its “Real Name” Policy; Drag Queens Celebrate
  Double X
The XX Factor
Oct. 1 2014 5:11 PM Celebrity Feminist Identification Has Reached Peak Meaninglessness
  Slate Plus
Behind the Scenes
Oct. 1 2014 3:24 PM Revelry (and Business) at Mohonk Photos and highlights from Slate’s annual retreat.
  Arts
Brow Beat
Oct. 1 2014 3:02 PM The Best Show of the Summer Is Getting a Second Season
  Technology
Future Tense
Oct. 1 2014 4:46 PM Ebola Is No Measles. That’s a Good Thing. Comparing this virus to scourges of the past gives us hope that we can slow it down.
  Health & Science
Science
Oct. 1 2014 4:03 PM Does the Earth Really Have a “Hum”? Yes, but probably not the one you’re thinking.
  Sports
Sports Nut
Oct. 1 2014 5:19 PM Bunt-a-Palooza! How bad was the Kansas City Royals’ bunt-all-the-time strategy in the American League wild-card game?