WHEN A 6 .0 magnitude earthquake rattled the tiny southern Monterey County town of Parkfield Sept. 29, locals took things in stride. Damage was minimal, nobody died, and they didn't even let the kids out of school early. It was just another shakeup, albeit a good one, in the self-proclaimed "Earthquake Capital of the World."

Scientists, however, were stoked. For decades they've known Parkfield, the midway point along the San Andreas Fault, as an area with high seismological activity – and some rare semblance of patterns to its temblors. Between 1857 and 1966 it withstood six magnitude 6.0 earthquakes, each about 22 years apart. Recognizing the chance to catch a canary in the Big One's coal mine, they'd spent years (and millions) hard-wiring the town with high-tech gadgetry and boring holes around the fault in the hopes of making headway in the elusive field of earthquake forecasting.

The North American plate, housing San Francisco, chugs northwest at a rate of roughly two inches a year. The plate gnashes along the fault line and builds up pressure. When there's a slip, there's a quake. When there's a big slip, it's like a giant zipper ripping through the earth – which is what happened April 18, 1906, during the estimated 8.3 magnitude quake that devastated San Francisco.

Seismologists divide the fault into three sections. The northern segment is relatively calm. The central segment, from San Juan Bautista to Cholame, belches out midsize, tension-relieving temblors. But the southern section is overdue, they say, and ripe for a whopper.

For some, that would be reason enough to keep a safe distance. But traveling the San Andreas has its appeal, not just for seismologists but also for anyone seeking undertapped California.

The fault's southern origin starts beneath California's largest artificial lake, the Salton Sea, famed for its populations of migratory birds and transplanted snowbirds packed into R.V.s (see "Accidental Lake," 10/20/04).

In nearby Palm Springs, a cottage industry has sprung up: four-by-four jeep tours head into the desert seeking not jagged gorges but palm trees and gurgling springs along the fault.

Farther north along I-5, Fort Tejon State Historic Park in Ventura County was the site of colonial California's largest quake, a 7.9 whumper in 1857 that leveled the army outpost and left a 200-mile-long rupture scar. Today restored adobes and historical reenactments recall California's pioneer days; campsites dot the surrounding Los Padres National Forest.

Westward along Highway 166, the San Andreas enters the rugged, barren Carrizo Plain, under the auspices of the Bureau of Land Management and home to the fault's most visible scars, with zigzagging streams, open gorges, and very few people around. Head north-northwest, and you'll hit Parkfield, where the scientists scurry about.

Climbers scramble across volcanic remnants and a unique dual-plate topography at Pinnacles National Monument, a day-use park that straddles the fault about an hour south of San Jose. North of Salinas, Mission San Juan Bautista has sat astride the fault since 1797 and withstood numerous quakes.

In the Bay Area, the San Andreas serves a utilitarian need: it's been dammed at San Andreas Lake to hold the water supply for San Francisco. You can view it while hiking the 1.5-mile San Andreas Fault Trail at Los Trancos Open Space Preserve in the Santa Cruz Mountains above Palo Alto. The Oct. 18, 1989, Loma Prieta quake occurred nearby on an offshoot fault of the San Andreas.

The coastal outcropping at Mussel Rock in Daly City marks the fault's departure out to sea, where it shoots north just past San Francisco on its way toward Marin County. Bikers and hikers can access the Ridge Trail from Skyline Boulevard (Hwy. 35).

More than water separates neighboring West Marin towns Bolinas and Stinson Beach, and the San Andreas created the Bolinas Lagoon. Each Fourth of July, town rivals square off for the tug-of-war that lands losers in the drink. At Point Reyes National Seashore, part of the Pacific plate, you can view fences displaced 15 feet by the '06 shaker on the Earthquake Trail at the Bear Valley Visitor's Center.

Meanwhile, firsthand perspectives of the 1906 quake grow more scant and precious. But you can still gather with survivors on its anniversary, 5:13 a.m. every April 18, at Lotta's Fountain, on Market Street at Kearny and Geary.

E-mail Jay Cooke

Trip planner

Parkfield Café serves barbecue beef ribs and ample lore. 70410 Parkfield. 805-463-2421.

Try Desert Adventures for four-by-four jeep tours outside Palm Springs. 1-888-440-5337, www.red-jeep.com.

Pinnacles Campground is located just outside the monument. 2400 Hwy. 146. (831) 389-4462, www.pinncamp.com.

In Olema, shop at the Epicenter (9960 Hwy. 1. 415-663-1239) and camp at Olema Ranch Campground (10155 Hwy. 1. 415-663-8001).