11/30/99 5:24:15 PM Pacific Standard Time:

Hi Kent: I'd like to know if you got any other reports from the Southern California region about the "Sky-Quakes" that we heard and felt this afternoon at approximately 15:40 PST? There were three (or more) of them all within a time period of 5 to 6 seconds. The only other information that I later learned from the local news radio station was a report of an earthquake around 15:45 PST that was felt in Orange County (20 miles away) and that Caltech was reportedly denying that there was an earthquake. To my senses it did not feel like an earthquake at all. But, I did feel the compressional sound wave when it came through the parking lot that I was standing in at the time of the event. Regards, Frank Condon http://www.geo-seismic-labs.org/

11/30/99 7:54:20 PM Pacific Standard Time

Frank, Have no idea what this critter was, however it did send a tremendous shock wave. We captured the signal which indicated a frequency  between 15 to 16 hertz which did have several peaks in very rapid succession.

Am enclosing pics which show the signal, times, and spectrum analysis. The frequency readout at the top of each graph indicates the peak between 10 and 20 hertz. Charlie Elfrad Group