Hi Ara. I can’t agree with you. The fault is there whether we know about it or not. It may take a quake to tell us there is a fault there, but the quake didn’t cause the fault.

Ever since an earthquake nearly destroyed San Francisco in 1906, Californians have dreaded the next Big One. The anxiety has been greatest for those who live near the San Andreas Fault, a dramatic 800-rnile-long gash in the earth's surface that comes within one mile of San Francisco and 30 miles of Los Angeles. However, evidence is mounting that this huge fault is only the most visible evidence of a threat that is much broader and more dangerous than once thought. Deep under the Los Angeles basin, the state's most populous region is a hidden group of faults, cracks in the earth's crust. Discovered only two years ago (at the time of this writing.) This underground network belongs to a new class of earthquake hazards that seismologists are just beginning to study. They believe similar undetected danger zones exist all over the world.

Suspicions were first aroused in 1983, when an earthquake--measuring a hefty 6.5 in magnitude, surprised the small, central-California town of Coalinga. The culprit turned out to be a fault that no one had realized existed. Reason: it was buried four to ten miles beneath the surface. This is the Great Valley Thrust Fault. In 1987 another hidden fault ominously creaked, this time directly under the city of Whittier, a scant twelve miles from downtown Los Angeles. It caused eight deaths and some $350 million in property damage. The fault has always been there. The time interval between quakes may be in the 100s to 1000s of years. In other words the last quake to have occurred did so before records were being kept, or before man was there to record those quakes. You don’t have to have a quake to get a fault. You have to have a quake to indicate there is a fault there.

The most dangerous fault there is is a blind thrust fault. It’s there, but no one can see it until there is a quake there.

I know of only one instance of where there may be a fault in the making. This is in Southern California. It is left lateral strike slip fault. There is some debate about this. There are a few seismologist who believe the fault has always been there, but inactive and has now become active again. Only trench digging and time will tell, then again maybe not. Take Care…Don in creepy town

• Birth of a Fault