Earthquake Predictions

Your Jan. 21 article about an 86% chance of a 7.0 or stronger earthquake in Southern California exemplifies how dangerous and misguided most of this research is today, and why so many buildings failed in Northridge and in Kobe. Buried in that article is the single short sentence, “The level of shaking was estimated (for the predicted earthquakes) at 20% of the force of gravity, far less than was recorded at the center of the Northridge earthquake.”

How ludicrous to waste taxpayers’ money producing a report that says the next earthquake, and presumably the “Big One,” will have an intensity of shaking far less than earthquakes we already have experienced. In the Northridge earthquake, a number of seismic instruments located in different parts of the Valley, and in Santa Monica, measured horizontal accelerations greater than 80% of the force of gravity. Common sense would dictate that we should now be designing our buildings to resist the higher ground motions which accompany shallow, vertical thrust-type earthquakes.

The current Uniform Building Code is loosely structured around an earthquake with a peak acceleration less than about 40% of gravity. The level of shaking a building experiences directly increases the stresses which cause failure and overturning. As such, we can expect substantial damage, injury and death if the predicted earthquake occurs and has peak accelerations several times that which is assumed in designs made according to the minimum requirements of the current code.

It’s time for the regulators, the politicians, and building owners to take charge of the situation and demand that the codes which are used to design buildings address the real risks inherent in Southern California. Yes, it will cost more money to design for these higher forces.

DAN FEGER, P.E.

Northridge

Enough is enough! Am I the only Southern Californian who thinks we have been far too inundated with the dire predictions of a massive Los Angeles quake? I absolutely agree that scientists needed to warn us to be prepared, and the Northridge quake certainly shook any “doubting Thomases” out of their lethargy and skepticism.

Now I think many of us who do not intend to flee Los Angeles are sick and tired of hearing about “the Big One.” We resent our children having to hear a promo for the 11 o’clock news stating, “Seismologists say L.A. is 70 years overdue for a monstrous quake.” We all know we “can’t rule Mother Nature,” but the scientists who are trying to save lives may be at “fault” in scaring us to death!

KAREN BERRENSON

Woodland Hills

The real story on the Kobe quake isn’t its destruction. Instead it is the marvelous dignity, calm and perseverance of its survivors.

ALLEN G. HOWLETT

Fullerton