Hi All. For years I have been saying I could never understand how we could get an M=5.4 quake in an area that has quakes all the time. With this in mind I decided just how many quakes we did have in the area of the 08/12/1998 M=5.4 quake. I started with the location of the quake then opened my search in 0.10Km increments. At 0.15Km I got my first quake prior to the M=5.4 quake. At 0.25Km I got 4 quakes. For those who are not metric inclined 0.25Km is equal to 820.2 feet. The distance is at the surface and doesn’t take into account the depth of the quake as you can see the depth of the quakes is much greater then 0.25Km.

Looking at the depth of the quakes I got to wondering if the quakes were caused by numerous small rocks coming in contact with one another or one very big rock coming in contact with smaller rocks and shearing those smaller rocks. You will note that there are two quakes separated by a little less then 3 years, two quakes then a little less then a 9 year period where there were two quakes in less then one day and then a little more then 8 years before the M=5.4 quake and no quakes in the area since then however when the search is opened to 0.35Km I get one quake that occurred 14 days later. The more I opened the search the more quakes I found. I did this until I was back to the point of wondering how we could get an M=5.4 in an area that has quakes all the time. I came to the conclusion that you really don’t need a very large area to get a large quake. All you really need is a couple of stubborn rocks determined to hold on for as long as they can before one decides to let go. When it does we have that large quake where someone like me wonders how we could get an M=5.4 quake where we have quakes all the time. Take Care…Don in creepy town

catalog=ANSS
start_time=1898/01/01,00:00:00
end_time=2006/03/06,00:45:44
minimum_magnitude=0.1
maximum_magnitude=10
event_type=E
delta=0 km to 0.25 km from (36.7533,-121.4622)
Date Time Lat Lon Depth Mag Magt Nst Gap Clo RMS SRC Event ID
----------------------------------------------------------------------------------------------
1978/06/23 01:06:31.32 36.7548 -121.4642 7.93 2.14 Md 48 31 2 0.17 NC -1040754
1981/05/29 01:54:08.33 36.7523 -121.4628 6.47 0.48 Md 4 186 3 0.01 NC -1064115
1990/01/22 18:53:45.26 36.7540 -121.4643 6.80 2.62 Md 80 32 2 0.17 NC 151480
1990/01/22 20:59:07.47 36.7520 -121.4600 4.05 1.44 Md 29 79 8 0.07 NC 151092
1998/08/12 14:10:25.12 36.7533 -121.4622 9.13 5.35 ML 78 35 4 0.21 NC 30190473