Guess and Tell Issue Bothers Quake Experts

A University of California earthquake expert questions just how much scientists should tell about their findings, or whether it does much good.

H. Bolton Seed notes the scientific community predicts that a major earthquake, on the order of the 1906 San Francisco jolt, is a probability in California within the next 25 years. And he agrees.

But he recalls that 20 years ago in nearby Berkeley he lived smack dab on the Hayward Fault, and that near him lived an elderly couple whose funds were tied up in their home. Should he warn them? He didn’t, and the couple lived out their lives without being uprooted.

The UC professor has since moved but doesn’t feel much safer.

Seed also notes Los Angeles put a notice on buildings that were considered unsafe from an earthquake and San Francisco did not. He doubts that the Los Angeles signs caused many people to move--only made them worry about the warnings.

Since the great 1906 San Francisco earthquake, building codes have arrived. They undoubtedly are a large improvement, but Seed says he’s sure some buildings will collapse in the next large quake despite the codes.

Questions About Water

A large part of the 1906 destruction was the lack of water because the earthquake broke water mains. After the quake, San Francisco built cisterns under the streets. But there have been street improvements since then, and whether firefighters can find the water in time is doubtful, the scientist said.

Seed made the observations while at a recent conference at the Fairmont Hotel, which stood through the 1906 quake but was gutted by the fire that followed.

He was attending a meeting of the International Conference of Soil Mechanics and Foundation Engineering.

Earthquakes occur because the world consists of blocks of land that rub against each other. The demarcation lines between the blocks are called faults. In California, the best-known fault is called the San Andreas; it runs through most of the state.

It is moving at a rate of about an inch a year, and within 200 years is bound to cause a major quake. But when?

Seed said home builders can take some precautions to improve their chances of escaping earthquake trouble.

For one thing, people can call in an engineer to select favorable land on which to build their homes. He points out that building on solid rock means the structure has a better chance. Churches built on rock have survived for centuries in Turkey, where earthquakes are common.

Building on sand, or fill, near an ocean is another matter.

That land, called “liquefaction” by scientists, is full of water, and a person will sink to his waist on it in case of a quake.

Seed said he has seen buildings in Japan which sank in such land and tilted as much as 80 degrees.