Hi Petra. Over the years of watching the various crustal deformation sites and seeing strain build which ended in a quake I came to the conclusion that with some large quakes the strain build up may be so slow that it is never perceived.

Take the Parkfield strain meters for instance. I have seen dilational strain build and there was an M>3.4 quake in the area of Middle Mountain. This was about 5 years ago. Then in 2002 I saw tensor strain build in the area of Turkey Flat Road and there was an M>3.6 just to the north of where the M>6.0 quake occurred. If one can see strain for a small quake then it stands to reason that one should be able to see strain for an M>6.0. However nothing was seen. Maybe the instruments weren’t sensitive enough, or the quake was to far away. Maybe the strain build up was so slow that it was never seen or recognized. The strain build became a part of the daily data.

In 1993 the magnetics in the area of the M>6.0 dropped. This was on the SW side of the fault. At the same time there was an increase in the magnetics on the NE side of the fault. I don’t know the exact location for the increase. It seems to me it should have been the other way around. This may account for why the animals never sensed anything before the quake as it has been reported for other quakes. Animals do a lot of strange things and yet quakes never occur. Take Care…Don in creepy town