Crossing the fault

摘要

In October, engineers from around the world met in Niigata, Japan, to hear about the first-of-a-kind pipeline design that will allow the San Francisco Public Utilities Commission to provide drinking water within 24 hours of our seis-mically active region's next major earthquake. The innovative solution we and our partners developed is one of the most critical reliability projects in the commissions Water System Improvement Program covered last month in this magazine (see "A regional plan for seismic security" on page 26 of the November issue). Two of our water systems largest transmission mains cross three traces — or strands — of the Hayward Fault, a 74-mile crack in the earth's crust east of the San Francisco Bay. Moving at a rate of 6 millimeters a year, the fault has caused, on average, a major seismic event every 140 years. The most recent was 143 years ago, so we're three years overdue.