Hi All. For about 2 years now I have been driving on Interstate 280 and I would notice how the hills were formed to the west of me. At first I thought it was due to the San Andreas fault, but then got to thinking that the contour of the hills were wrong for a strike slip fault. I have been aware of the Monte Vista thrust fault and it approximate location for more then a year now, but now I know exactly were it is, or at least most of it. There are parts of it that can’t be seen and probably never will be seen until the next large quake occurs on one of them. There are homes and industry built one of the Monte Vista thrust fault. As a matter of fact there are some homes that use the slope of the Monte Vista thrust fault in the landscaping of the yards. Take Care…Don in creepy town

This was taken from the Palo Alto Weekly and was printed in 1994.

by Rufus Jeffris
A series of Peninsula thrust faults, similar to one that is being blamed for the destructive Los Angeles temblor Monday, could produce an earthquake of similar force somewhere between Redwood City and Cupertino, according to two Stanford University geophysics professors. In a research paper written last year for the Seismological Society of America, Robert Kovach and Gregory Beroza called attention "to evidence for an additional source of potentially damaging earthquakes on the San Francisco Peninsula."

Their work identifies two seismically active areas, the Stanford fault zone and the Hermit-Monte Vista fault zone, which it states are capable of generating earthquakes of up to 6.2 and 6.6, respectively, on the Richter scale.

Monday's temblor in the Los Angeles area registered 6.6 on the Richter scale.

"We're not out of the woods, yet," Kovach said.

Thrust faults, also called reverse faults, occur when one slab of earth moves diagonally against another. They differ from so-called strike-slip faults, in which two vertical slabs of earth move against each other. The San Andreas fault is California's best-known example of a strike-slip fault.

According to Mary Lou Zoback, a geophysicist at the U.S. Geological Survey in Menlo Park who cited the work by the two Stanford professors, the Peninsula's thrust faults are created by "the squeezing motion of the San Andreas fault" as it bends along California's coastline.

"We're starting to recognize that these faults don't produce big earthquakes" as strike-slip faults do, she said. "But they're occurring with more frequency."

The Stanford fault zone begins near San Francisquito Creek just south of Santa Cruz Avenue in Menlo Park, stretches southeast through the university and cuts across Page Mill Road, where it creates a slight rise near Hanover Street.

Smaller thrust faults exist within the zone, Kovach said, including one which passes directly under Frank Lloyd Wright's famous octagonal Hannah House on Frenchman's Road.

The Hermit-Monte Vista fault zone is larger than the Stanford zone, starting in the foothills near Redwood City and Woodside, stretching southeast between Interstate 280 and the foothills, passing under the Stanford Linear Accelerator near Sand Hill Road and traveling in a line toward Cupertino and San Jose.

Kovach forecast a "better than 30 percent chance" that one of the local thrust faults could generate a temblor of magnitude 6 or greater sometime in the next 30 years. He also said that movement or a rupture on the nearby San Andreas fault could trigger subsequent earthquakes on the Peninsula's thrust faults.

Although forecasting earthquakes is highly inexact, Kovach said, a lack of significant seismic activity in the area between San Francisco and Portola Valley in the last 20 years could indicate the Peninsula is due for a big one.

Kovach noted, however, that the work he and Beroza are doing is far from complete. He said they have not identified all existing local thrust faults and "blind thrust faults," which produce no visible trace on the Earth's surface and are more difficult to locate. Blind thrust faults were also thought to play a role in the Los Angeles shaker.

"We have kind of ignored the Peninsula," Zoback said.