I admit to being sadly remiss in the study of plate-techtonics and geological, uh, stuff. Undoubetedly, this is why I never heard the word "fore-shock" before this weeek. Yet, in the last two days I've heard it at least five times from the TV weather and news guys.
We're having our CA paradise version of FL hurricanes and mid-west tornados these days - earthquakes have been rumbling the left-coast lately. Nice big rumbly ones that can be felt for hundreds of miles from their epicenters (another term that I managed to grow up for thirty years in New England without ever using once in a sentence).
Anyway, the geologists are telling us that the first 5.9 quake Monday was a singular stand alone event, but that the 5.2 yesterday south of the first one, was an after-shock of the 5.9. However, they also are noting that an after-shock can be a fore-shock of another quake, and that we have a one in twenty chance that there will be another big after-shock making the quakes a series.
At first, I was confused as to how geologists would distinguish between fore-shocks and stand alone earth quakes, until an exhuberant geologist from Cal Tech (I think) explained that we can't know if a rumbler is a stand alone or a fore-shock until a period has gone by with either another rumbler, or else nothing. And some times it might be months or weeks until we can really say for sure. But that sometimes, what looks like a stand alone might really be just an unfulfilled fore-shock. And then, of course, sometimes, a rumbler might be a fore-shock whose normal trajectory is subverted by another random event like for example a disconnected geological phenomenon rendering it in actual fact ultimately a stand-alone.
(Aren't you all glad we have science to be certain about instead of just the immeasurable uncertainties of religious faith?)
The geologist on TV this morning was particularly urgent that we all know that if a big quake happens along the fault in the next few days, that we should all consider it an after-shock and not a singular stand alone rumbler.
I'll try to remember that as my cat and I are falling through four floors of our apartment building, sofas and bookshelves raining down all around us.