Probability map for a >5.0 earthquake within 50 km of Washington DC
In June a colleague used a US Geological Survey Earthquake probability tool to explore the likelihood of a 5.0 or stronger quake occurring within 50 km of Washington D.C. Maybe once in 5000 years is what he decided.
How time flies.
Of course, that’s not exactly how probability works. But however you treat it, Tuesday’s 5.8 tremor was a rare event along the east coast. Statistically it was “improbable.”
When speaking of events that have the potential to seriously disrupt society and kill lots of people, we should stop using the word “improbable.” Somehow in ordinary English improbable implies “safe to ignore.”
There are some eventualities of which we can be certain, but are beyond our ability to situate in time and space. We can confidently anticipate these events, but precise prediction is beyond our current capability… and potentially impossible.
We can anticipate the general characteristics of Hurricane Irene. We cannot be sure if she will visit Times Square, Montauk, or the Delaware Water Gap. We have a better sense of when rather than where she will arrive. Wherever she washes up, Irene will be an unwelcome guest.
Hurricanes entering New York harbor are infrequent. Earthquakes strong enough to crack the capitol dome are infrequent. Major dam failures are infrequent. Terrorist attacks are infrequent. Will they happen? Almost certainly.
Somehow, I am much more likely to give some sustained attention to that which I know is infrequent, than to what I perceive is improbable.