In the Santa Cruz Mountains, Loma Prieta's Impact Lingers
The earth opened up next to a home located on the Summit in the Santa Cruz Mountains. (U.S. Geological Survey)
It was twenty five years ago -- Oct. 17, 1989, at 5:04 pm -- that a 6.9 magnitude earthquake jolted the San Francisco Bay Area. The Loma Prieta quake killed 63 people -- most of them crushed in their cars when a double-deck freeway in Oakland collapsed.
But it was also chaotic in cities and towns closest to the epicenter, about 10 miles northeast of Santa Cruz. Buildings in downtown Los Gatos and Santa Cruz crumbled. In Watsonville, just north of the Monterey County line, migrant farmers were forced to live in tents in the center of town.
Right outside these areas, in San Jose and on the peninsula, the earthquake effects were relatively minimal. Dr. Tom Brocher, the director of the Earthquake Science Center at the U.S Geological Survey in Menlo Park says the shock waves went deep in that area.
“The wave went down and bounced off the bottom of the earth’s crust, bypassing the places in between San Francisco and the Santa Cruz Mountains, so they didn’t feel that extra dose of shaking,” Brocher recalls.
For days the magnitude of destruction near the remote epicenter in the Santa Cruz Mountains was overlooked. Thousands of homes were heavily damaged in the violent shaking, including my own. I recently returned to my old neighborhood to talk to people about the quake's lasting impact on the way homes are built today.
Kevin Zaknich was watching the World Series when the quake hit. He bolted outside, then realized he was at the edge of a canyon with huge redwood trees. They were shaking as his mountain home split apart. He thought a tree would fall on him and kill him. To this day, the sound of the quake haunts him.
“It sounded like a freight train, but a freight train is too simple," he recalls. "It was just this loud, moaning noise that rattled you to your soul. It was crazy."
And it was devastating. Eleven miles below the surface, the San Andreas fault was releasing hundreds of years of geological pressure. It ripped apart roads, triggered landslides and made propane tanks explode.
My family and I were away when the quake hit and first watched it play out on a television screen in Sonoma County. For two days, we couldn’t get up the mountain to discover we'd lost almost everything inside the house we rented. It was later red-tagged -- unlivable until fixed.
Zaknich's home was destroyed. It was among the thousands of homes in the mountains that were not bolted down well enough to withstand a 6.9 quake.
“It was a small cabin that came off the pier blocks," Zaknich recalls. "A deck split from the house; an addition split from the house."
In the quake’s aftermath, Geotechnical Engineer Patrick Shires inspected close to one thousand damaged homes that lurched off their foundations in Santa Cruz County.
“There were cases where there were a lot of these homes built without permitting, so they were not built to any code,” Shires says.
Built Stronger Today
Structural engineer Carol Scott was getting 40 calls a day after the quake to fix homes. She says Loma Prieta was a wake-up call. After tightening home building codes following the quake, Santa Cruz, Santa Clara and San Francisco counties have the strictest home building codes in Northern California for bolting and addition connections. Scott says the new homes are prepared for a quake as big as an 8.0 magnitude.
“We design for an eight," Scott says. "And we are basically giving you time to get out of the structure.”
Zaknich says the stricter building codes and influx of Silicon Valley money have had a big impact on his neighborhood.
“The earthquake changed it dramatically," he says. "A lot of the houses went from funky little cabins to well-built luxurious homes.”
Today, soil tests must be done before home building can even begin in the Bay Area, Shires says. It’s determined if the soil is sand or clay, whether there is a landslide risk and how deep and wide a foundation is needed.
“We write a report containing all the analysis," Shires says. "It is thousands of dollars.”
Many of the people who lived in the Santa Cruz Mountains during the quake are now gone. Kevin Zaknich still works on the mountain where he grew up, but lives in Santa Cruz.
“If there is another quake, I hope I’m on a beach somewhere, and it’s nice and flat" Zaknich says, "and I don’t see any redwoods.”