Timothy Lesle

This is Part II of this article. Read Part I here. You can download the entire text (without images) as one file here. The following was reported in late 2007 and early 2008.

At 7:53 in the morning on October 21, 1868, a major earthquake struck the Bay Area. It had a magnitude of about 7, scientists believe. It occurred on the Hayward Fault. The shaking lasted for more than 40 seconds and damaged property throughout the Bay Area. Thirty people died. It was known as the “great quake” until the 1906 earthquake supplanted it. Most of the buildings in Hayward suffered severe damage or were destroyed. As one USGS publication notes, “few places have paid so dearly to have an earthquake fault named after them.” This is the earthquake that Tom Brocher and his 1868 Hayward Earthquake Alliance want people to know about.

On a bookshelf in Brocher’s office at the USGS campus in Menlo Park sits an empty box of novelty earthquake cake (“My wife gave it to me. But I ate it,” he admitted). Next to it is a small toy globe with a little string dangling from it. Brocher pulled the string and the planet trembled in his hand. He considered an Arnold Schwarzenegger bobble-head doll on another shelf. “I haven’t taken it out of the box,” he said, “but it would be a good earthquake detector.”

The alliance is a coalition of public and private bodies dedicated to raising awareness of, and promoting preparation for, the threat posed by the Hayward Fault. (Stoffer told me that it was Brocher who asked him to put together the Hayward Fault guide.) The Bay Area has a 63 percent chance of a major earthquake in the next three decades, and the Hayward Fault is the likeliest to rupture. “We tell people there’s a two-thirds chance,” Brocher said. “Somehow it’s not as compelling as telling the 140-year story.”

Brocher does not look forward to another earthquake. He remembered the 1989 Loma Prieta earthquake, the last major quake to hit the area.

“Generally when you feel an earthquake, you feel it at its maximum and it kind of decays,” he said. “That earthquake, every new wave was bigger than the one before. They just kept getting bigger and bigger and bigger, and I wondered, ‘When is it going to stop getting bigger?’”

But he cautioned against using the Loma Prieta as an indication of what to expect from a Hayward earthquake. For one thing, that quake was too far away. “The Hayward Fault—when it ruptures, it’s going to be in people’s back yards. That’s the reality we need to prepare for. It’s no good preparing for Loma Prieta.”

It’s an 1868-style earthquake that worries Brocher and the alliance. The Bay Area was far less developed in 1868. Hayward was a town of about 500 people; San Francisco had 150,000 residents. More than five million people would feel a Hayward quake today. A trillion-and-a-half dollars worth of property would be at risk.

Those figures come from a company called Risk Management Solutions, headquartered in a corporate office park in Newark, south of Hayward, along the edge of the bay. Its specialty is modeling catastrophes and quantifying their risks for insurance companies—whether earthquakes, hurricanes, terrorism, or plagues. A portrait of Tetsuya Fujita, whose name puts the “F” in the F-scale of tornado strength, hangs in one hallway. In the lobby, display cases hold free reports on China’s 1976 Tangshan earthquake and the threat of a flu pandemic.

RMS predicts losses of about $165 billion worth of property. Of that, $75 billion would be commercial; the remaining $90 billion would be residential property. “They’re staggering numbers,” said Mary Lou Zoback, vice president of earthquake risk applications at the company and a geophysicist. Only a fraction of that is covered by insurance, and, after deductibles and limits to coverage, insurance companies are only on the hook to pay about $4.5 billion to homeowners affected by a quake.

“In insurance terms, we call it a super catastrophe, or super cat,” she said. The effects ripple beyond the immediate losses, as people have difficulty getting to work and utilities—water, power, gas—take time to come back on line, resulting in lost business and wages. “People come from other countries and say, ‘We’re in America, the most advanced country in the world. Surely it’s better prepared than, say, Guatemala.’ Well, it may not be.”

The 1995 earthquake in Kobe, Japan, helps put the potential damage from a Hayward quake in perspective. Kobe is sited along the Osaka Bay, and its Nojima Fault is the same kind and roughly the same length as the Hayward Fault. It is a major population center bound by mountains on one side, water on the other, and heavily populated flat land in between. In Kobe, a phenomenon called liquefaction was a major source of damage. When liquefaction occurs, the ground loses stability because it is saturated with water. As a result, buildings, sidewalks, roads, and other structures can sink or tip over. Geologists expect similar damage along the margins of San Francisco Bay, as well as strong shaking throughout the flatlands. The Oakland and San Francisco airports, as well as all port facilities, may be severely affected.

Much of the major infrastructure of the region has been, or is in the process of being, retrofitted to improve its ability to withstand earthquake. But homes and businesses are another thing. In 1996, the Earthquake Engineering Research Institute released a report on the possible effects of a Hayward quake. One chapter is entitled “Commercial and Residential Buildings Affected by Ground Motions.” It was written by a structural engineer who traveled along the fault, highlighting buildings that he expected would be damaged or destroyed. Twelve years later, he doesn’t think much has changed.

“Since 1906, the Bay Area’s only experienced one big earthquake: Loma Prieta in 1989,” said Brocher. “So in the last hundred years, we’ve only had 15, 20 seconds of strong shaking. That’s not much over a hundred years.”

During that century, much of the infrastructure of the Bay Area was built: the freeways, the bridges, the skyscrapers in San Francisco, the continuous band of homes and businesses along the Hayward Fault. Brocher contrasted this with the half-century before 1906, when earthquakes measuring in the magnitude five to six range occurred every two or three years. Brocher thought that if these kinds of earthquakes happened more often, it would spur greater preparedness.

Brocher opened a drawer in his desk and pulled out a booklet called “Putting Down Roots in Earthquake Country,” a guide describing the region’s seismic situation and how residents can strengthen their homes. He flipped to a chart showing the number of known earthquakes higher than magnitude 5.5 since 1836. Each earthquake was represented by a rectangle that indicated its size. The largest rectangle was in 1906. The 1868 and 1989 earthquakes also figured prominently. From 1928 to 1968, there were no notable earthquakes at all. The timeline stretched into the future, showing a 62 percent probability of at least one earthquake of magnitude 6.7 or higher by 2032.

“We call this the tombstone diagram,” Brocher said.

The Claremont

“Any reason I can’t park here?” Stoffer asked as he stopped his car in what was clearly not a parking spot. The Claremont Resort and Spa nudges against the fault for about a fifth of a mile and he wanted some pictures of the building. He had navigated through a couple of small lots on the Claremont property, but all were full. He ended up on a triangular wedge of asphalt on one of the hillside lots overlooking the building.

Stoffer stepped out of his car to a commanding view of the shimmering white hotel: white walls, white roof, white tower. He set up his tripod with the dual cameras and leaned back, squinting at each of the cameras. He snapped a pair of photos for his field guide. I asked him if he had made the camera rig himself. “Oh, yeah,” he answered. Then joked, “Boredom.” Stoffer has been shooting 3-D photographs for years. One of his biggest projects is a web site highlighting the geology of the Southwest’s national parks. His office is like a museum of fossils and crystals he’s collected over the years. On one wall, over his desk, is a mounted jackalope head. It wears a pair of red and blue 3D glasses.

Stoffer headed down the hill to the entrance. Valets scurried under a green awning, helping new arrivals with their luggage and their cars. A stylish young woman hurried out of the building, talking into her cell phone about a spa appointment. Stoffer walked past the valet station to what looked to be a small maintenance passage. According to his map, a known trace of the fault was less than a hundred feet away. He noticed some cracks in the wall, then leaned close and looked along the plane of the wall. It was slightly warped. A nearby cement planter appeared to be pulled apart. And, in the valet parking lot, between a pair of late-model Mercedes sedans, Stoffer spotted what he called a pull-apart offset, creating a tiny rift in the fresh blue-black asphalt. None of this was definitive, but all of it, as far as Stoffer was concerned, was highly suspect.

“It’s a tough game to find creep movement,” a geologist named Jim Lienkaemper said one afternoon in his office at the USGS. The evidence around the Claremont, for example, has always been “kind of iffy stuff.” Lienkaemper has been studying the Hayward Fault for 20 years. A fresh printout was taped to his door. It was a graph covered with little hieroglyphics, the product of his latest Hayward Fault survey. Each fall he maps it again, surveying the infinitesimal distances that different sections of the fault crept during the previous year.

Over the last few millennia, the earth along the fault has moved an average of about nine millimeters every year, almost four inches. That number is the combined movement from both the gradual creep and the abrupt slip along the fault from a quake. Measuring the amount of creep at a given segment of the fault gives an idea of how much movement might occur in an earthquake. In other words, if Lienkaemper measured nine millimeters of creep each year along some segment of the fault, he wouldn’t expect major slip there during an earthquake because all of the tectonic energy was being released. But the average creep rate along the Hayward is about 4.5 millimeters each year, not far enough to release all that stress. In a big earthquake, he speculated that sudden ground movement of a meter or more might be seen on the surface.

The crack Stoffer found at the Claremont could be another, unmapped trace of the fault. Lienkaemper acknowledged that he can only map the traces he knows about. There are always undiscovered traces. “We’ll know when the Big One comes,” he said. “We’ll have a lot of new stuff to map.”

Back in the Claremont parking lot, Stoffer approached the valet station. An attendant asked if he could be of assistance.

“Do you know where the Hayward Fault is?” he asked the valet.

The valet looked puzzled and thought for a moment. He scratched his head. “Doesn’t it run through Cal Stadium?” he asked.

Stoffer grinned and swung his arm toward a spot beyond the Mercedes sedans. “It’s right there!” he said. The valet smiled politely, but didn’t say anything else.

“It’s classic,” Stoffer told me soon after. “He works there and he doesn’t even know.”

Next: The conclusion of Devoted to a Fault, including notes on preparation activities and UC Berkeley’s Memorial Stadium.
[Photo at top from Bancroft Library and the Online Archive of California. Diagram by USGS.]

By Tim | 11th June 2009 at 8:28 pm
Filed under: earth
Tags: 1868, Bay Area, california, catastrophe, Claremont Resort, geology, Hayward Fault, history, Japan, Kobe, Mary Lou Zoback, Oakland, predictions, Risk Management Soluctions, Tom Brocher, tombstone, US Geological Survey