(Canie posted for Barbara)
Barbara posted the following article in the Earthwaves Board

Dated : November 06, 2005 at 01:46:28
Subject: EWPF Registration

I have been following this board daily for a couple of months now and I have a few questions.

I've always heard that there is a 1 in 20 (or 5%)chance of a larger quake (in the next week?) after a quake has occurred.

But, intuitively, the larger the quake, the less likely a larger quake will occur -- after all, how much chance is there of topping a Mag 9 earthquake?

So my question is: Is there a higher probability of a larger quake, following a smaller quake, that diminishes as the magnitude of the smaller quake is a larger number? In other words, is there an inverse relationship of probability of a larger quake occurring and the magnitude of the original quake?

Also, I've seen a list before -- but don't remember where -- of how many earthquakes of Mag 3 or 4 or 5 or 6 California gets in a year, on average. Can someone post that? It's just a matter of curiosity -- how have we fared so far this year? Are we above or below average?

One more question: In the major earthquakes, say Mag 6 or above, what is the weather like? I've always heard of "earthquake weather," but I've also heard that that has been debunked. However, I do remember vividly the weather in So Calif on Feb 9, 1971 was warm and beautiful. And, as I recall, it was nice weather in Northridge on Jan 17, 1994. And wasn't the weather good in Pakistan before the recent quake there? (And then the rains came.) I know that's a small sample, only three instances, but I don't remember hearing about a large quake occurring during a rainstorm -- I could be wrong though.

I have always been interested in seismology -- well, maybe not always, but ever since the 1971 Sylmar earthquake which caused major damage to our house in Granada Hills and a forced evacuation (the Van Norman dam was in danger of bursting open). Hence, I follow earthquake-related news items, articles, books...and this board. I don't always understand everything you are talking about, but I do try to learn from it.

I wish I had studied seismology in school instead of being practical and majoring in Finance and then getting an MBA. Subsequent employment as a Financial Analyst paid the bills, but I certainly wish I understood more about earthquakes.