California

Getting Ready For The Big One
By Larry Wright, December 23, 2000
mailto:wright@iinet.com

The current USGS Earthquake Map for California and Nevada shows many micro earthquakes from the Southern Nevada border to the southern portion of California. In addition you will notice similar earthquake activity running the length of the state along faults just east of the San Andreas. There is little or no activity on the San Andreas Fault itself which follows the California coastline. The Ocean side of the San Andreas Fault is moving north while the continent side which is moving south. At a point just above Santa Barbara on the California coast there is a outcropping of land called Point Conception. The San Andreas Fault goes around Point Conception as it follows the California coast line south through Los Angeles Harbor on down to San Diego. This area can be seen on the map just above the group of islands off the Southern California coast known as Santa Cruz, Santa Rosa and Catalina Islands. The San Andreas Fault is unable to slip past Point Conception. This is the only area along the entire fault line that does not run in a relative straight line.

Despite this fact the north / south movements of the tectonic plates are continuing. This is resulting in an enormous rip or tear across the state from the Southern California coast to the Nevada border as the two plates drag past each other. This is also triggering micro earthquakes along the numerous minor faults running the length of California. But no major action has occurred along the San Andreas. This is a clear indication that pressure and stress along the San Andreas is building to a critical level. The area preventing a major slippage of the San Andreas is Point Conception. No earthquakes have occurred in the Point Conception area. If the area around and through Point Conception begins to fracture the San Andreas will be free to move. Eventually this must happen as pressures continue to build. The rip in the state can only take up so much of this movement before something snaps. In my opinion the snap will occur in the Point Conception area. Once a fracture crosses Point Conception and joins the San Andreas on each side cutting through the point, the San Andreas will begin to move. This sudden snap movement will release a tremendous amount of energy all along the San Andreas fault from Southern California to the northern part of the state.

I hope I am wrong about this in so much as I live in the Southern California area. But in studying this earthquake map I can come to no other conclusion. The earthquake swarms and the many faults and fractures shown on this map southeast of Point Conception toward Nevada indicate a pressure relief due to lack of movement of the San Andreas through Point Conception. How much longer this will continue before the big one strikes is anyone's guess. USGS and other scientists conclude that there is a 70% probability of at least one magnitude 6.7 or greater quake, capable of causing widespread damage, striking the San Francisco Bay region before 2030. Judging by this map I think it will be much sooner and much greater than anticipated.