California caught between drought and the 'Big One'

TWO LONG shadows have fallen over the sunny landscape of southern California. They concern the darkest fears of a society which has long grown used to the idea that it is living in a semi-desert on America's western rim which probably should never have been populated: earthquakes and drought.

After studying the volatile web of geological flaws underlying the state, seismologists have concluded that the odds of a devastating earthquake within the next five years have increased significantly. At the same time, water- starved California is heading for its seventh year of drought, the longest dry period for 400 years.

The earthquake warning was largely the result of the Landers quake (7.5 Richter magnitude) that shook up a sparsely populated southern desert area in June. Although there was limited damage, it was the worst quake in the state for 40 years, and increased the pressure on the San Andreas Fault, a flaw that runs up most of the state like a fat underground firework, waiting to explode. A team of leading seismologists have concluded that this, and other recent rumblings, increased the likelihood of a major quake - magnitude 7.0 or more - within the next five years to almost 50/50. By way of comparison, the earthquake which caused widespread destruction and killed more than 60 people in the San Francisco Bay area in 1989 was a 7.1.

Setting odds for earthquakes is tricky and imprecise, and the scientists, brought together by the US Geological Survey and the state's emergency planning officials, included plenty of qualifications in their findings. But they reported that portions of the San Andreas Fault appear 'ready for failure', and concluded by emphasising the 'plausibility of large damaging earthquakes affecting metropolitan areas of southern California'. Heavily populated areas near the fault include Los Angeles' dormitory cities of San Bernardino and Riverside.

Californians tend to be cavalier about the prospect of the 'Big One', if only because they have been warned many times before. But now there are signs of genuine alarm: more than 1,000 callers swamped an earthquake safety hotline demanding copies of the report. The media have run stories advising people to bolt down their furniture and stock up on food.

If these prophecies have an apocalyptic flavour, so too do the forebodings of the state's water officials. They say that Californians should prepare for a drought emergency this year. Reservoirs are only half-full and ground-water supplies are under heavy pressure. Much of California's water comes from reservoirs in the mountainous north, and is carried by aqueducts to the south where the bulk of the 31 million population is concentrated. Last year rainfall in the north was nearly 30 per cent below normal.