The odds against a major earthquake happening on the day I arrive in central California to write about earthquakes are approximately 8,030 to 1.
If only I were a betting man. It hits at 10:15 a.m. on September 28, 2004, as I am biting into a breakfast bar, waiting in a trailer at the San Andreas Fault Observatory at Depth. The project is using an oil-drilling rig to bore deep into the infamous fault, allowing geophysicists to plant instruments at the precise spot where earthquakes begin. At first I think the rig, roughly 100 yards from the trailer, is making the ground vibrate, but soon the trailer’s floor is juking and jiving beyond all reason.
“Oh my God, it’s an earthquake!” shouts geophysicist Naomi Boness, clutching her desk. I appreciate the professional confirmation.
Photograph by Vicky Samburnaris A team of roughnecks pull giant hydraulic wrenches from a freshly joined section of pipe. “These guys are amazing,” says geophysicist Naomi Boness. “They can tell you what kind of rock they are going through just by the way the drill behaves.” |
Everything becomes a bit nutty after that. The quake is felt over a 500-mile-long area, so a whole slew of local news media rapidly converge on the tiny town of Parkfield, population 18, which is about eight miles from both the earthquake’s epicenter and the drill site. I drive there and count 13 live-TV trucks on the dusty street. Television reporters try to put tough, in-your-face questions to Stephen Hickman, the U.S. Geological Survey geophysicist who is one of the observatory’s chief investigators.
TV REPORTER: So, did you guys cause this with your drill?
HICKMAN: No.
Meanwhile, I am stunned and weirdly jumpy all day. With the trailer rolling and yawing dramatically even in this modest temblor, the fact that earthquakes have killed more than 1.8 million people since 1900 is suddenly very easy to believe. The indirect effects of a temblor can be equally deadly, as demonstrated by the devastating Indian Ocean tsunami that struck last December. One has to wonder how many of those people would have lived if they had known in advance that an earthquake was coming.
“Earthquake prediction is the bugaboo of geophysics. People don’t even like to talk about it,” says Mark Zoback, a professor of geophysics at Stanford University and another principal investigator at the drill site. Right now scientists understand far too little about Earth’s inner motions to make reliable earthquake forecasts, and the cost of an unreliable forecast could be huge: Millions of dollars of business would be lost by shutting down San Francisco for a week awaiting a temblor that might never arrive. On the other hand, even a few minutes of advance warning would allow enough time to evacuate people, shut down gas and water lines, and save a city from ruin.
Zoback picks his words carefully as he explains why he is drilling into the San Andreas Fault. “With this project, we are not trying to learn how to predict earthquakes, but we are trying to see if they are predictable. Whatever we find will be interesting, because it’s never been done before.” Hickman echoes the sentiment: “What happened today is a reminder of what this is all about.”
| Putting Earth Under the Microscope The San Andreas Fault Observatory at Depth is one of several elements of EarthScope, an ambitious $200 million initiative by the National Science Foundation that is investigating the geophysical forces that shape the North American continent. The other projects within EarthScope include: The Plate Boundary Observatory—Global Positioning System receivers at about 1,000 sites, combined with strainmeters at about 200 locations, are being installed along the western edge of North America from Alaska to Mexico. The aim is to monitor the continent’s ongoing shrinking, bulging, and general deformation, watching changes over timescales ranging from days to decades. United States Seismic Array—A network of seismic stations, including portable ones that will be moved across the entire United States over a 10-year period, will map subtle differences in the seismic energy traveling through our planet, yielding an improved understanding of deep-earth structures. Interferometric Synthetic Aperture Radar—A proposed satellite-based monitoring system that, if funded, will track the movement and deformation of the North American and Pacific plates by bouncing radar waves off the surfaces. This technique could identify ground motion as small as one millimeter. |
The San Andreas Fault Observatory at Depth is located 25 miles northwest of the spot, near the intersection of Highways 41 and 46, where James Dean wrecked his Porsche Spyder and died on September 30, 1955, an event commemorated by an unattractive, stainless-steel roadside shrine erected by a Japanese businessman. All around is remote, desolate, sun-blasted cattle country dotted with live oaks, brown grass, and weather-beaten barns. The nearest gas station is 20 miles away, cell phone service is virtually nil, and Alice, the desk clerk at the four-room Parkfield Inn, asks me to close the gate behind me to keep the wild pigs off the porch.
The fault behaves oddly here. Formed by the Pacific and North American tectonic plates grinding against each other, the San Andreas Fault curves up 800 miles from the Gulf of Mexico, slicing a shallow arc across western California. The north and south sections are locked together, slipping rarely but violently, leading to quakes like the 1906 monster that killed 3,000 people in San Francisco. The section just north of Parkfield is different. It moves all the time at about the speed human fingernails grow, roughly 1.3 inches a year. Build a house there and it would be ripped in half in slow motion.
The five-acre drill site, a 12-minute drive from Parkfield, is on the transition between the southern, locked section and the creeping section. Zoback, along with Hickman and William Ellsworth of the U.S. Geological Survey Earthquake Hazards Team, decided to drill here because this transition zone cranks out little magnitude 2 quakes, too small to feel on the surface, with metronomic regularity every couple of years. These are repeating earthquakes, meaning they produce identical seismograph patterns, “wiggle for wiggle,” says Zoback. Monitoring how the ground moves repeatedly, at many different depths, will allow the team to piece together the world’s first three-dimensional map of a fault in action, like peering straight into the rock. The “observatory” part of the project’s name is more than just metaphor.
