I agree with Larry and others that earthquake predictions do not belong on this mailing list. There are a number of web sites that are dedicated to earthquake predictions and that is where the predictions belong. I used to post to one of those bulletin boards and became the "keeper of hits and misses". Up to that time, no one was actually keeping track of how accurate the predictions were (expect for the predictions by the "famous person" that had the web site). Of course I had to set up some guidelines for determining hits and misses. A specific location (within a radius of a stated number of miles), a specific time (no limit), and a specific magnitude. Then I gave a a "fudge factor" of 10%. It was mentioned by the "famous person" that he had been working on a method of grading predictions and it included all of the above, but also a "quality factor". In other words, what are the odds of that quake happening? After all, if I were to predict a M3.5 within 50 miles of San Francisco during the month of September, 2000, I would be very confident that I would get a hit! Over time, I'm sure I would be very nearly 100% accurate. When I started "grading" hits using the odds factor, it really showed a lot more than just a hit or miss. I was asked to stop using the grading system because some people would get so discouraged that they would stop posting earthquake predictions. I stopped using the grading system, but still feel it is necessary. There are some problems with earthquake predictions that many people don't think about. First of all, when someone predicts an earthquake and they get a "hit", what about the other earthquakes (with magnitudes that could cause damage) that they *didn't* predict? But, I think the major thing that needs to be considered about earthquake prediction is what, if anything, should be done in an area where a large earthquake has been predicted? Let's say that a person/method can predict 90% of all quakes in a particular area. Let's further say that the magnitude accuracy is within +/- 10% of the actual magnitude. Since most predictions are not for a specific date and time of day, let's say that the accuracy for time is within +/- 3 days. I think we would all agree that that method was very, very good. Now, this ficticious method predicts a M7.1 earthquake within 25 miles of San Francisco on September 27, 2000. Of course, how far ahead of the predicted quake the prediction is made is important, but let's say it was made today, September 17, 2000. So, we have 10 days! What does the government do about this? Do we evacuate all of the people from a 25-mile radius from San Francisco from September 23 though October 1? I think you can see where I'm going with this. I would like to say that there are some people/methods of predicting earthquakes that have *some* merit. Although I had not visted the web site I mentioned above, I did go to it after the "Hector Mine" earthquake in the Twentynine Palms area just to see if anyone had predicted that one. I found that for a few days before (perhaps as much as a week before) two people in particular were warning of a large quake in the Twentynine Palms area. In fact, one of them went as far as to say "If I lived in Twentynine Palms, I' get out of town for the weekend." Interesting!! "JD" Cooley Poway (San Diego County) __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Larry Cochrane <cochrane@..............>