Some of the headlines this morning read, “Last night’s 7.1 quake was five times more powerful than Thursday’s 6.4 quake.” This is absolutely correct, and yes, we felt it in Phoenix. How is it that a 7.1 is 5x stronger than a 6.4? I’m glad you asked!
The Richter magnitude scale is not a linear multiplier, but rather, exponential. Each increase in whole number represents a 10x increase in magnitude. The accelerating force of exponents is best learned graphically:
So as the exponents increase, the scale keeps getting steeper, or taller.
Here is another graphic that is really helpful in order to relate the numbers to past actual earthquakes, as well as notable examples of energy releases. Remember your physics class: An earthquake is essentially a sudden conversion of Potential Energy into Kinetic Energy, like an explosion or a lightning bolt, so we are able to compare magnitudes between these.
If you were alive in the United States in 1989, you surely remember the Loma Prieta quake, because it happened on live TV during the broadcast of the World Series in San Francisco (yes, back in the 80s, everyone still watched the World Series). The damage was quite widespread, with the enduring images being cars driving off the collapsed Bay Bridge, the pancaked double-decker Nimitz Freeway in Oakland, and the fires in the Marina District. I can still remember how nauseated I felt upon seeing the pancaked freeway, wondering how many cars were crushed beneath. HERE
That was a 6.9 magnitude. If yesterday’s 7.1 had hit a hundred miles farther south, at Palmdale on the fault line, Los Angeles would be in ruins right now.
Stay frosty, and stay Confessed.
For video of chandeliers shaking and pools overflowing, IN ARIZONA, go HERE.
For a terrifying exercise in exponential arithmetic and the fate of your eternal soul, go HERE.