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THIS WEEKEND, A 3.3-magnitude earthquake rattled San Francisco ever so slightly. The small quake, like so many before it, passed, and San Franciscans went back to conveniently ignoring their seismic reality. Magnitude 3.3 earthquakes are clearly no big deal, and the city survived a 6.9-magnitude earthquake in 1989 mostly fine—how how much bigger will the Big One, at 8.0, be than 1989?
Ten times! As smarty-pants among you who understand logarithms may be thinking. But...that's wrong. On the current logarithmic earthquake scale, a whole number increase, like from 7.0 to 8.0, actually means a 32-fold increase in earthquake energy. Even if you can mentally do that math—and feel smug doing it—the logarithmic scale for earthquakes is terrible for intuitively communicating risk. "It's arbitrary," says Lucy Jones, a seismologist with the US Geological Survey. "I've never particularly liked it."
[Suggested New Earthquake Scale]: Seismological Review Letters
Maybe SN could suggest a better way to measure earthquakes ...
(Score: 3, Interesting) by MrNemesis on Friday August 14 2015, @07:38PM
When I was doing geology circa 2000 (when TFA was puslished by the looks of things?), using the Richter scale was already old hat - all the earthquakes were measured in moment magnitude [wikipedia.org] as per the article mentions. News reports even managed to make using the Richter scale even more meaningless by not even saying which magnitude measurement they were using or... worse still, taking the moment magnitude (MMS) issued by the $seismometer_owner and calling it a Richter scale measurement (was always a drinking forfeit if you heard that on the news). But it is at least broadly compatible with the Richter scale in terms of the numbers being broadly similar.
Incidentally, in case it's not common knowledge - earthquakes are typically measured by a) a number of different magnitude calculations (of which MMS was the preferred method I was taught), to estimate the amount of energy released (i.e. it's the same figure regardless of distance) and b) an intensity scale, typically the Modified Mercalli [wikipedia.org] which measures local effects. As such an earthquake is always of a given magnitude, but the relative intensity of it typically drops off with distance from the epicentre.
"To paraphrase Nietzsche, I have looked into the abyss and been sick in it."