Monday, November 7, 2011

Richter Scale

No matter how well I understand how logarithmic scales work, my puny human brain doesn't understand it intuitively.  For example, the Richter scale.  My brain thinks a 5.0 earthquake is almost as bad as a 7.0 earthquake and a 9.0 is not much worse than that.  However, if you look at total energy released, it becomes a miracle Japan did not sink into the ocean or that anyone is alive over there.

One way to better grasp the intuitive size of an earthquake is to translate the logarithmic Richter scale into something linear, like total energy released.  This can be thought of as roughly the destructive power of the earthquake.

4.0 -- People who've never felt an earthquake before think this is a big earthquake
63 GJ

5.6 -- Oklahoma earthquake
16,000 GJ

6.7 -- Northridge earthquake (LA)
710,000 GJ

7.1 -- Loma Prieta (SF)
2,800,000 GJ

8.0 -- Lots of (unhappy) places and predicted for SoCal at some point
63,000,000 GJ

9.0 -- Japan
2,000,000,000 GJ

So intuitively, the earthquake in Japan is like 125,000 Oklahoma earthquakes all at the same time.  My silly puny brain doesn't even understand what 125,000 sizable earthquakes at once would feel like.

Source - Wikipedia -- I don't claim this to be a scientifically sound analysis; it's just to give an intuitive sense of sense of scale and how bad we are at communicating it to each other.