Zig-Zagging Through Quake Country

Approaching Parkfield on Cholame Valley Rd., near the oil pipe bent by the 1966 earthquake.

By Tommy Hough

Several years ago, in the prehistoric days before iPhones, I was calling 805 information from a pay phone at a diner in Paso Robles, 24 hours after a magnitude 6.0 earthquake rattled the doors and floors of little Parkfield, California, about 40 miles away in the middle of Monterey County cattle country. It was already late at night.

Though less intense than a more destructive earthquake that killed two people in Paso Robles a year earlier, this particular Central Coast quake was determined to have been the Parkfield earthquake the U.S. Geological Survey had been patiently waiting decades to catch "red-handed." Now, with the hills around Parkfield humming, a scientific benchmark had arrived at something of a full circle.

The kid on the other end of the line with 805 information called me a brave man for angling to spend the night in Parkfield, still rattling with aftershocks. It didn't take bravery, of course – just some wise curiosity and fascination at the mechanics of planet Earth playing out centimeters at a time. The quake was becoming big news in the seismology world, and a landmark in the annals of California seismic events despite its remote location and fortuitous lack of damage. A German TV crew had even been on hand shooting a Discovery Channel program, and just happened to film the earthquake as it happened.

A few minutes later, with reservations set and endearing directions guiding me to the Parkfield Inn, I was on my way to the self-proclaimed Earthquake Capitol of the World, in the San Andreas Fault-created Cholame Valley in southeast Monterey County. To me it was a natural reaction. Who wouldn't want to experience the aftermath of one of nature's most amazing geologic acts in a reasonably consequence-free environment?

In 2001 I rode out the Nisqually Earthquake from my apartment in Seattle's Queen Anne neighborhood. While hanging onto my bedroom door as the building violently lurched from left to right, I remember watching as my wastebasket waddled its way into the middle of my kitchen floor as the refrigerator wobbled out its enclosure, and wondered how much more violent, side-to-side shifting my concrete block building would take before splitting in two.

Driving east through the night on the speedy two-lane blacktop of State Route 46 through Paso Robles wine country, I reminded myself to drive with caution. The northbound cutoff onto Cholame Valley Road, which takes motorists into Parkfield, is an abrupt left turn lying just beyond the point where James Dean was killed in a head-on collision in 1955. Beyond the Parkfield cutoff is the busy merge of California routes 41 and 46, where trying to slow down to a reasonable speed to make the turn grows confusing among a dizzying array of ramps, headlights and signals.

But headlights and signals are absent the moment you turn north into the striking darkness of Cholame Valley, where you're suddenly greeted by a jarring, metal cattle grate several hundred feet north of the turn, abruptly reminding motorists this is not a road on which to let the mind wander either.

Throughout its history Parkfield's residents have been reminded they live in earthquake country. Curiously low, abrupt ridges indicating somewhat recent fault movements, called scarps, line either side of the valley, and good-sized quakes have rattled this otherwise quiet corner of California every 25 or 30 years, keeping residents up at night as aftershock cycles recede and the barking of agitated dogs subsides.

Despite the media attention occasionally lavished on the area, Parkfield has managed to enjoy a quiet, un-gentrified remoteness few Golden State communities have been able to maintain, like a bypassed mountain town. But in contrast to mild-mannered, placid Parkfield, the surrounding geography implies ominous goings-on. The hamlet lies on the wild, treeless slopes of the Coast Mountains in a range named for the Spanish word for earthquake: temblor.

Though not indicated on most pre-1857 maps of the state, the Temblor Range was surely named by Spanish-speaking settlers of the day who knew the long-term secrets of the mountains from native Chumash and Yokut Indians. Following the great California earthquake of 1857, estimated to be a magnitude 7.9, the Temblor Range name stuck.

The 1857 shock, which held the record for nearly 100 years as the largest earthquake in Southern California, originated in the southern end of the Cholame Valley and ruptured south through the Carrizo Plain, stretching across some of the most remote, mysterious areas of Kern and San Luis Obispo Counties. Though the 1857 quake was felt strongly in Parkfield and cracks and surface ruptures appeared along Parkfield's stretch of the San Andreas, the great 1857 temblor wound up being named for Fort Tejon – which, at the time, was the biggest population center in the region.

Now a state historic park just off I-5 at Tejon Pass along the Grapevine, Fort Tejon was a military outpost along Grapevine Canyon hundreds of miles south of Parkfield, high above the southern portal to the San Joaquin Valley in another strange geologic keystone of California, where the Coast Range drifts inland to meet the Tehachapi Range near the summit of 8,800 ft Mount Pinos.

Fort Tejon took the brunt of the 1857 shock in terms of damage and injuries, and the San Andreas Fault itself was ruptured far east of Tejon Pass. Motorists still drive over this stretch of the San Andreas while traveling on I-5. Heading north from Pyramid Lake near Castaic, the freeway passes over the San Andreas Fault where two valleys merge just south of Gorman, a mile or so south of the Tejon Pass summit marker. A walk-up fault exposure can even be seen in a hill adjacent to I-5 along the east side of Gorman Post Rd., about 30 feet north of a Caltrans maintenance shed.

In addition to 1857, quakes of an estimated magnitude 6.0 or greater were felt again in Parkfield in 1881, 1901, 1922 and 1934. After the 1934 quake a pattern appeared to be developing, and another quake was generally anticipated by Cholame Valley residents and the few scientists studying the area. But it wasn't until the morning of June 27, 1966, when a water pipe mysteriously ruptured in a field just south of Parkfield that suspicions were raised that the fault was jockeying into position and "creeping" in a manner that would indicate an impending slip, and a resultant earthquake.

That evening, the next magnitude 6.0 Parkfield earthquake rumbled through the area. As scientists from the U.S. Geological Survey began to analyze the data, they realized they could make Parkfield a living laboratory where they could potentially catch the next "regular" 6.0 shock – if the pattern of earthquakes in the Parkfield area remained intact.

Though forecasting an earthquake was never seriously considered by the U.S. Geological Survey, scientists were confident they could at least catch an earthquake red-handed. Data from one seismic event could help them understand the natural mechanics of fault creep, or ground slippage, along the San Andreas either prior to or just after sizable shocks, as well as the mechanics of the earthquakes themselves. A few years later, with funding secured, the Parkfield Experiment proceeded.

Slowly but surely, the town of Parkfield – its ranches, fields, and oak-dotted hills – began to play host to the most densely-packed array of seismology equipment on the planet, as the U.S. Geological Survey made the monitoring of Parkfield a full-time job. By the early 1980s a generally assumed window of opportunity for activity began to open, and scientists cautiously rubbed their hands in anticipation of catching the next Parkfield shock as it happened.

Mother Nature, however, had other plans.

Coalinga is an old mining and railroad town 28 miles northeast of Parkfield, in a pocket of Fresno County on the west side of the San Joaquin Valley and east slope of the Diablo Range, a sister Coast Mountains range north of the Temblor. While a pair of freeway signs along I-5 in the Central Valley identify the off-ramps as Coalinga exits, the town still lies about 20 miles to the west of the freeway, in part via State Route 33.

Like the Temblor Range, the Diablo is also made up of wild, rolling hills – a bizarre effect of surface deformation caused by overt drainage, and millions of years of movement along the nearby San Andreas Fault, where the Pacific Plate is slowly grinding northwest at the rate of a centimeter or two a year. Like the Temblor Range, the Diablo – Spanish for "devil" – has an ominous, occasionally otherworldly appearance. And on May 2, 1983, Coalinga was jarred by a destructive magnitude 6.5 shock which came completely out of the blue.

Spawned by one of dozens of parallel branches along the San Andreas within and around the Diablo Range, the entire Coalinga event occurred underground, with no evident surface rupturing or visible cracks. Some scientists presumed the release of energy in the Coalinga shock relieved pressure thought to be growing on the main branch of the fault in nearby Parkfield.

As rescue efforts and aid descended upon stricken Coalinga, scientists in Parkfield began to wonder if they'd been thrown a violent curveball. Even if the 1983 Coalinga earthquake was the anticipated Parkfield shock hitting in another locale a few miles away, it could have sufficiently thrown off the timing of the fault in the Parkfield area. Scientists realized it could be another 20 years before the expected quake finally arrived in Parkfield. They were right: it took 21 more years.

In the intervening years after the 1983 Coalinga quake California continued to bump and grind through some of the most destructive earthquakes in the state's recent history, including the Loma Prieta and Northridge earthquakes, with the expanding level of damage and injury in each shock a testament to the Golden State's swelling population and expanding urban areas, which put far more people into harm's way than ever could have been imagined by California's gold rush founders.

By the summer of 2004, with the U.S. Geological Survey continuing to comb through data from the deadly San Simeon earthquake nine months earlier – the one that killed two people in Paso Robles – the Parkfield experiment appeared to be a quaint relic of an earlier era of progressive, proactive funding, somehow surviving into tighter, cost-cutting times.

The notion of utilizing data from an earthquake which had yet to happen in order to predict earthquakes, or give definitive signs of active fault creep in the hours prior to a quake, had largely been dismissed in favor of more concrete realities in the wake of the dramatic earthquakes which visited California after 1983. Nevertheless, the USGS retained a myriad of seismometers and GPS instruments around Parkfield, some of which had been in the ground for 20 years, and maintained a small office in a nondescript brown trailer south of town.

On the morning of Sept. 28, 2004, over 38 years since the last sizable jolt in Parkfield, the moment arrived which vindicated the Parkfield Experiment’s founders.

At 10:15 a.m., just as the German television crew was shooting footage for a documentary on the Parkfield Experiment, an oil drilling apparatus used by the National Science Foundation's EarthScope Program was boring towards the fault to place monitoring instruments at a ranch just north of town. For the earth sciences community, it was in many cases the culmination of a career's work.

In the resulting 6.0 magnitude earthquake no one was hurt, and little if any property was damaged. The Parkfield Experiment had come full circle, albeit far out of its predicted window. A magnitude 5.0 aftershock hit Parkfield two days later on Sept. 30, highlighting an aftershock sequence which continued for months into 2005.

Seismologist and author Susan Hough (no relation) of the USGS Pasadena office told the on-line publication Geotimes, "It's going to be a huge boon scientifically," with instruments aligned all around the epicenter bound to pick up "incredible data," adding to the legacy of the Parkfield Experiment with real-time data sets, models and new information the experiment's scientific pioneers knew could be attained – if agencies and the public were prepared to wait along with the earth's own inconsistent pace for the results.

Even though I arrived in Parkfield hours after the main Sept. 28 shock I still managed to miss the Sept. 30 aftershock, but it didn't matter. It was fascinating and even thrilling to be back in the Cholame Valley at a moment of discovery and revelation, not to mention drastically lowering my stress level in one of the quietest, most pleasant locales in the Golden State.

A drive up the gravel Parkfield Grade over Mustang Ridge is a great way to see Parkfield and the Cholame Valley from above, and if you find yourself staying at the Parkfield Inn ("sleep here when it happens"), perhaps you'll be able to say hello to the friendly basset hound who enjoyed basking in the sun on the not-so-busy main thoroughfare between the inn and the Parkfield Cafe ("eat here when it happens") in 2004.

As far as the young man taking calls for 805 information the night I called, courage is certainly required for a variety of endeavors, but it doesn't take bravery to want to see the earth at work, even in minute, small ways. And a good road trip is a good road trip.

"If I have ever made any valuable discoveries, it has been owing more to patient attention than to any other talent."  –  Sir Isaac Newton

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At Cholame Valley Rd., east of Paso Robles in the heart of the Temblor Range.