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Bay Area residents can take a virtual
helicopter tour of the region's deadliest
geological time bomb, the Hayward Fault, just
by pointing and clicking.
Unveiled Thursday by the U.S. Geological Survey, the online tour, which resembles an aerial overflight from an altitude of a few hundred feet, allows the viewer to see exactly how close a particular piece of property – including his or her home, school, gym, favorite coffeehouse or commuting routes – is to the fault.
The images, which merge USGS data with Google Earth's celebrated online library of aerial photographic maps, are of such high resolution that a user can spot individual homes and, in some cases, people. They include thousands of faceless football fans during an actual game at the UC Berkeley stadium, which the fault neatly bisects.
The tour covers some of the densest urban terrain in California, USGS scientists and state and municipal officials pointed out at a news conference in Menlo Park on Thursday. The Hayward Fault, which gashes through the East Bay, including Berkeley and Oakland, is the likeliest locale for the next big California quake, experts have forecast.
"The Hayward Fault is locked and loaded. It is ready to fire at any time," said Tom Brocher, co-coordinator of Northern California Earthquake Hazards for the USGS office in Menlo Park.
Experts have previously estimated a major East Bay quake could render 155,000 housing units uninhabitable, Jeanne Perkins of the Association of Bay Area Governments said at the news conference.
The online tour is available free to anyone who has access to the Web and to the necessary Google Earth software. It was developed by geoscientist Jim Lienkaemper of the USGS' Menlo Park office. Lienkaemper developed the virtual tour by merging Google Earth imagery with USGS records showing foot-by-foot changes in the position of the fault.
The Hayward Fault is a result of long-term stresses between the ever-moving North American and Pacific geological plates, which are divided by the more famous San Andreas Fault to the west. The Hayward snakes unevenly through the East Bay and occasionally breaks into pieces or disappears under landslides or urban development, as the virtual tour shows with spectacular clarity.
Other USGS scientists are now developing an online aerial tour of the San Andreas Fault, which they hope to unveil later this year.
Knowledge of one's closeness to the fault is valuable for property owners because their buildings are especially likely to suffer severe damage – for example, cracked foundations or busted pipelines.
However, USGS experts warn anyone who uses the virtual tour: Don't relax if you discover that your home isn't right on the fault line. During an earthquake, the bulk of damage is caused by ground shaking, which can wreak horrific damage – including busting pipelines, etc. – many miles from the fault.
Rather, one real advantage of knowing your location in relation to the fault is that it allows family members to prepare for quake-triggered family separations, Perkins said.
Suppose, for example, that you check the online tour and discover that your home is in Oakland, on one side of the fault, while your daily workplace is south of the fault, in San Jose. Because many East Bay highways are perilously close to the fault, there's a good chance that after a quake, highway and road shutdowns will prevent you from returning from work to home. Also, the quake might disrupt or overload phone communications. These and other factors might prevent you from doing things you normally do every day – say, picking up the kids from school, or ensuring that a pet at home gets a full bowl of water.
Thus, Perkins asked: Have you made emergency preparations for such a disaster? For example, by ensuring that a neighbor will pick up your kids from school, or feed your dog? Come the next quake, such "family reunification" crises, as Perkins calls them, could be no small concern.
Because of highway positions in the East Bay, "probably hundreds of thousands of people are commuting across this fault every day," she said.
March 10, 2006
https://www.sfgate.com/bayarea/article/BAY-AREA-Virtual-overflight-shows-urban-fault-2502456.php