Earthquake fears fade

Press, 4 May 1984, Page 20

Earthquake fears fade

By

JONATHAN SHARP

NZPA-Reuter

San Francisco When the ground started shaking near lunchtime on April 24, a common reaction among San Franciscans as they dashed for safety, scrambled under tables or simply froze, was: “Is this the big one?” Ever since the city was devastated by a huge tremor in 1906, it has been part of San Francisco lore that “the big one" will happen again. The only question is not if, but when. California is astride a tangled maze of faults, the breaks in the Earth’s crust that separate continentsized “plates” of rock which, when they jostle and strain against each other, cause earthquakes. The upheaval on April 24 which registered 6.2 on the open-ended Richter scale and was strong enough to cause serious damage, in fact caused more fright than harm, mainly because it was centred away from big population centres. California will not always escape so lightly. The Office of Emergency Services, a United States Government body, estimates that in the next 20 to 30 years, California will suffer what seismologists term a “giant” quake with a magnitude of 8.5. The office forecasts that

the quake will kill between 3000 and 15,000 people, render 10,000 homeless and cause SUSIS billion in economic loss. What the Government cannot say is exactly when or where in the state this disaster is going to occur, because, despite considerable research, the art of earthquake prediction is still in its infancy. Leading the quest for a means of forecasting earthSuakes is the United States Geological Survey (U.S.G.S.), a Government organisation whose west coast headquarters is in Menlo Park, south of San Francisco and conveniently close to the most famous of California’s faults, the San Andreas.

The U.S.G.S. has 500 monitoring stations scattered around California recording every subterranean shudder, however slight. The staff say they are nowhere near to being able to say with confidence where and when the next significant jolt is going to be. The only forecasts they can make are vague, and couched in terms of probabilities. For example, based on historical patterns of earthquakes, areas near Los Angeles in southern California are now at greater risk than San Francisco.

Most vulnerable of all, according to a U.S.G.S. staffer, Allan Lindh, is the

tiny central Californian community of Parkfield, population 34, which is almost certain to experience a substantial earthquake in the next five years.

Mr Lindh is confident that prediction techniques will improve. “Ten years from now, we will have gone a long way,” he said.

“We will be able to make statements about big faults and big earthquakes that we can’t do now.”

In the meantime, seismic surprises will continue. The shock on April 24 came without warning, despite the fact that it occurred on the fairly well-known Calaveras fault.

“We have always believed there would be damaging earthquakes on the Calaveras, and we believe there will be in future. But this does not tell us when those will take place,” said a California geologist, James Davis.

A more damaging earthquake last May that destroyed a fifth of the homes in the town of Coalinga, about mid-way between San Francisco and Los Angeles, came as a complete surprise.

Also surprising is that even though Californians live with the threat of a destructive earthquake hanging over them, relatively few seem to care enough to take out quake

insurance. Immediately after the April 24 tremor, insurance companies in San Francisco reported a rush of inquiries about earthquake insurance. “It’s always like this after a big shaker,” said one broker.

In many instances, the applicants were turned down because most companies have a rule against selling earthquake insurance immediately after a big quake because of the likelihood of aftershocks occurring. The moratorium can be as long as 30 days.

Even those with earthquake insurance often allow their policies to lapse during periods of seismic calm. Only about 5 per cent of homes in California are now insured against quake damage, according to the latest available figures.

People quickly forget about the danger of earthquakes, it seems. A day after the April 24 tremor, San Francisco’s newspapers were turning their attention back to local political issues, including a debate over what the city’s official song should be.

One of the contenders is the melody, “San Francisco,” sung by Jeanette Macdonald in a 1936 movie about a topic of enduring interest: the 1906 earthquake.