On Sun, 17 Sep 2000 ddiffenderfer@........ wrote: > I live about 100 miles east of the San Andreas in Southern California at > Palo Verde and remain interested in predictions done scientifically. So > far I am not aware of anyone that can predict quakes with any accuracy by > any method. > David. W. Diffenderfer > ddiffenderfer@........ Hi All, I just moved to LA, and have just been going through the messages concerning prediction. This is a very interesting topic indeed. I had the pleasure of attending a symposium last week which went through several statistical models and fancy number schemes which may be applied to prediction. The best talk was given by Dave Jackson, who has been interested in this topic for some time now. He used only raw data from the past to try and model future activity...and the result: you have a better idea of earthquake risk from looking at a map of previous seismicity than just about any other method. I think that anybody will find this simple method hard to beat! There have been many studies over the years, with little success. One such was that a temporal gap in seismicity should usually preclude a large earthquake. However, looking at plots of the rates of seismicity for many fault zones it was easy to see that this rarely works. There are also papers I have seen that report ULF magnetic field variations, but this stuff is still locked into the problem of "statistics of small numbers" and has to be studied much further to understand both the mechanism for changing the magnetic field as well as the character of a signal before a large quake. Also, a lot does not make sense yet to the field seismo people. For instance, a section of the San Andreas is creeping and just next to it is a section which is locked. How the kinematics of the transition between the two styles along the fault work is anyone's guess. Recently this year, I sent two references to the group from a paper in Science and one from Nature that report annual variations in seismicity for some spherical modes and also for aftershocks following the Landers quake. This is probably some kind of atmospheric effect which is not totally understood either. Another paper coming out soon shows that the San Andreas speeds up and slows down in its average motion over time...so I guess what I am trying to say is that there is a lot about earthquakes that is not yet understood. New information and findings are constantly coming in, any of which can effect the over all processes. ****************************************************************************** John Hernlund Department of Earth and Space Sciences University of California, Los Angeles E-mail: hernlund@....... or hernlund@............ WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Larry Cochrane <cochrane@..............>