Hi Don and Petra,

Thanks for all the great info on the area and associated fault systems. The main reason I look at Tejon Pass area, is because it appears to me to be the center of the locked area in the "big bend" (thanks for the term Don.) That being said, we know the locked areas release the most stress when they finally give, and tend to generate the higher magnitude quakes. I look to Tejon Pass as an indicator of sorts, in that any activity in the locked segment shows it's trying to free. It seems very interesting that the center of the locked region at T.P. is also the intersection of the Garlock fault. How do they relate? Don is right of course, the locked region extends from San Bernadino all the way up to Parkfield, so any break along that stretch could be a big one.

I made a map of CA, and plotted the coordinates of five of the largest quakes since 1872. They form a semi-circle which runs completely around the locked region, from east of Los Angeles up to San Francisco.

The quakes I plotted were:
Owens Valley, 1872, 7.8M, 36.6N, 118.1W
Loma Prieta, 1889, 6.9M, 37.04N, 121.88W
Landers, 1992, 7.3M, 34.13N, 116.26W
Northridge, 1994, 6.7M, 34.21N, 118.54W (inside of semi-circle)
Hector Mine, 1999 7.1M, 34.6N, 116.27W

Of course, this doesn't mean a whole heck of a lot with the limited number of quakes I plotted, but I thought it was an interesting pattern and worthy of further study. It almost appears that they're trying to bypass the locked region. There were a number of large quakes I haven't plotted yet, which form a smaller semicircle around LA, and out to the sea through Northridge, below the locked region.

I'd love to see an animation of every quake over 6 that we have records of. The data from 1769 - 1900 is highly suspect though, since it was mostly based on peoples perceptions.

I just found this data table of major California and Nevada earthquakes, 1769-1989. I'm trying to figure out a way to plot and animate them. Anyone got any ideas, or know if we could use animation software that's already been developed?

Take care, Billion

• TABLE 6.1.-Major California and Nevada earthquakes, 1769-1989.