Hi All. Over the period of years I have seen various methods used by people trying to predict earthquakes. They have their good points and bad points. To date I haven’t seen one method that tells you where and when that major quake is going to occur. To do that you have to know how much stress there is at the location of the expected quake.

When a major quake occurs the stress for the most part is relieved in the area of the quake, but what happens to the surrounding area? Does the stress just disappear or does it lower the stress at some locations while at the same time increasing it at other locations? An example is the San Francisco Bay area, where the great earthquake of 1906 reduced stresses across the bay, causing a lull in moderate-sized quakes that lasted until the1979 quake near Morgan Hill, California. The opposite occurred in Turkey along the great North Anatolian fault. A large quake in 1939 sent stresses farther down the fault, triggering a 60-year series of quakes whose latest installment was the deadly Izmit earthquake of 1999. The stresses have risen in the crust near the city of Istanbul, and a quake there is now considered more likely.

From using the crustal deformation sites in San Juan Bautista and Parkfield the one thing that I noticed is that there is no gradual increase in strain. I’m sure it’s there, but is so subtle that one has to really look to see it. The one thing I saw with the 7 quakes I predicted for the Hollister/San Juan Bautista area was a rapid increase in strain. It would peak, level off, and then drop. All of this took place in less then 36 hours. I don’t know if this is the way all faults act, or if it’s this particular fault in this particular area. I couldn’t tell what the magnitude of quake was going to be by looking at the strain meter, but knowing the history of the quakes that have occurred in the immediate area I was pretty confident that it wasn’t going to be a major quake however I couldn’t say that it wasn’t going to be a major quake. Without sufficient knowledge of where sufficient stress is located no earthquake prediction program is going to predict a major quake. Take Care…Don in creepy town