Every day in Sonoma County, thousands of people pass in and out of masonry buildings that could be at risk of collapse in an earthquake, a danger that persists three decades after a state law required cities and counties to address the hazard.
While Santa Rosa, Sonoma, Healdsburg and Petaluma have managed to retrofit most of these high-risk buildings for seismic safety, Sonoma County officials say there are about 170 in unincorporated areas, from Geyserville and the Russian River area to Penngrove, including retail shops, offices, fire stations, restaurants, schools, post offices, churches, meeting halls, warehouses, night clubs and wineries.
Some are landmarks and cherished historic structures; others are nondescript, utilitarian buildings. Some are in use nearly every day, and others appear to be shuttered. They are built of brick, stone or cinder blocks mortared together, largely without the connective strength of steel rods required for decades by building codes to hold structures together.
There are 7,800 of these structures — officially dubbed unreinforced masonry buildings, or URMs — in 29 counties, and they are at “significant risk of collapse,” according to the state Seismic Safety Commission.
The magnitude-6.0 temblor that struck a week ago today in southern Napa County focused new attention on California’s unfinished business with URMs, designated as a threat to public safety in a 1986 law that required cities and counties to inventory the buildings and develop remedial programs.
‘A huge success story’
The quake, which rattled Sonoma County residents — and people living more than 100 miles away — at 3:20 a.m. Aug. 24, hit hardest in Napa County, with damage and economic losses expected to hit $1 billion, according to an initial estimate by the U.S. Geological Survey. On Saturday, Sonoma County declared a state of emergency, estimating damages at $4.5 million, more than half to wineries. But most of the damage has been to contents rather than the buildings, and one owner of a retrofitted brick hotel in Glen Ellen was ecstatic with the way her structure fared.
“I’m happy to say, so far, we sailed through it,” said Christine Hansson, co-owner of the 107-year-old Hotel Chauvet, a three-story landmark in Glen Ellen. “It’s a huge success story.”
A few drawers slid open and some pictures were knocked askew on walls, Hansson said after inspecting the building, which has been converted to six condominium units. The elevator was running, the swimming pool intact and there was no structural damage, she said.
The yellow brick hotel, left vacant for two decades, partially collapsed in 2004, prompting Hansson and her partners to spend about $300,000 on renovations, gutting the building and bracing it from top to bottom.
“It’s expensive, but it was worth it,” Hansson said. “And the building is there to say it.”
Tennis Wick, director of Sonoma County’s Permit and Resource Management Department, ranks the Hotel Chauvet among the county’s notable seismic retrofit projects. Much work remains to be done, however, elsewhere across the region.
In 2006, the county identified 315 URM buildings and had whittled the number down to 204 by the time last Sunday’s temblor struck. The quake “gave us new urgency,” Wick said last week, after dispatching inspectors to check the buildings — with the owners’ permission — and assure all are posted with warning notices regarding their condition.
The notice, spelled out by the state URM law, says: “Earthquake Warning. This is an unreinforced masonry building. You may not be safe inside or near unreinforced masonry buildings during an earthquake.”
Wick initially said he was focusing on about 25 buildings that are places of assembly, such as private schools, gathering halls and churches. He broadened the effort to inspections of all the unreinforced masonry buildings countywide, starting in Sonoma Valley because of its proximity to the quake’s epicenter. On Friday, the department released an updated tally of 170 URMs on 151 properties.
“We are just tightening up the list,” Wick said, adding that the number is likely to grow smaller as the inspections are completed, probably by early October.
“Seismic safety upgrades work,” he said, noting that retrofitted buildings checked last week “fared very well” in the quake.
Structures needing retrofits
Structures that remain on the county’s list include fire stations in El Verano and Monte Rio; buildings at Martin Ray Winery, Korbel Winery and Buena Vista Winery, among others; Odd Fellows halls in Guerneville and Geyserville; buildings at the Salvation Army’s residential treatment complex north of Healdsburg; and the Larkfield shopping center off Old Redwood Highway.
Structures on seven parcels at Rio Lindo Adventist Academy outside Healdsburg are on the list. They include dormitory and instruction buildings, a gymnasium and a cafeteria. The 52-year-old private school, with a student body of about 200, sits on 360 acres along the north face of Fitch Mountain.
Douglas Schmidt, the school’s principal, did not return calls for comment last week.
Concerns about seismic safety and other issues have led the Monte Rio Fire Protection District to seek $5 million in grant money to replace its 60-year-old station on Main Street. The firehouse, which is on the county’s list, is surrounded by structures that are far older, including an adjacent concrete retaining wall that dates to 1900 or earlier, said Ken Wikle, board president of the fire district. The foundation for the new station would need pillars driven deep into bedrock to make it strong enough to withstand a large quake, which could liquefy soils along the river, Wikle said.
“We have a lot of safety concerns here, and our firehouses are one of them,” said Monte Rio Fire Chief Steve Baxman. “I think if we had that same temblor here on the river we’d have a lot of problems. Ours would be the buildings, and it would be the bridges.”
Guerneville’s River Theater, built in 1947, is also on the county’s list of unreinforced masonry structures. Theater owner Jerry Knight insists it shouldn’t be, however, saying the concrete walls are reinforced with steel. He said he has punched two holes in the walls to show inspectors the metal.
Knight, who has owned the building since 2010, was cleaning up at the theater when Sunday’s quake hit.
“This place took a ride, I’ll tell you what,” Knight said. “It got me going.”
The 1986 law applied to 365 local governments in 29 counties, most on or near the coast and close to historically active earthquake faults. Cities and counties were allowed to tailor their own remedial programs.
The designated area, known as Seismic Hazard Zone 4, initially had 25,945 URMs, and about 70 percent, or 18,144, were either retrofitted or demolished, according to the Seismic Safety Commission’s latest tally, reported in 2006. That left 7,801 URMs standing, with the public “exposed to life-threatening risks,” the report said.
“That’s why we keep pushing,” Richard McCarthy, the commission’s director, said last week. State law, however, includes no penalties for failure to fortify a URM, leaving that to local discretion.
“I think it’s good progress,” McCarthy said. “I think that’s quite remarkable.” Had the recession not struck in 2008, depressing property values and tax revenues, more URMs would likely have been retrofitted, he said.
McCarthy and local building officials noted that shoring up old brick and stone buildings does not guarantee, nor is it intended, to assure they ride out an earthquake unscathed. “Bricks will fall down,” McCarthy said, and retrofitted buildings may even be damaged beyond repair.
The point, he said, is whether the occupants “get out alive.”
Sonoma County’s cities, by dint of circumstance and a desire to preserve their historic downtown buildings, have eliminated the majority of URMs.
Santa Rosa was literally shaken into an early start by two earthquakes that struck 83 minutes apart on the night of Oct. 1, 1969, generated by the Rodgers Creek Fault, which is even now the fault most likely to trigger a major quake in Northern California.
The twin temblors of 1969 — magnitude 5.6 and 5.7 — walloped the old brick buildings in Santa Rosa’s commercial core. There were no dramatic building collapses, but structural damage doomed 100 commercial buildings, prompting an urban renewal program that included the downtown mall.
In 1972, 14 years before the state URM law, Santa Rosa enacted a seismic retrofit program applied to a wide range of buildings, including URMs and some wood-frame buildings. Every building permit request for more than $50,000 of work, or more than 10 percent of a building’s value, or for any re-roofing triggers a seismic safety inspection, said Mark Setterland, chief building official.
In any masonry or concrete building, a key issue is ensuring that the floors and roofs are effectively tied to the walls, he said, noting that separation from the walls during a quake can lead to the building’s collapse.
After checking city records, Setterland estimated that Santa Rosa, as of 2000, had identified 78 URMs, of which 58 were retrofitted and nine demolished. That leaves 11 URMs that remain unrepaired or partially repaired, and all are currently unoccupied, he said.
If the owner does not apply for a building permit, no city review occurs, Setterland said.
“Santa Rosa is basically way ahead of the game,” he said. “I believe we’re in a lot better shape than other areas.”
Petaluma, virtually unscathed by the earthquakes of 1906 and 1969, still had a trove of historic brick buildings in the 1990s. Following the wake-up call of the 1989 Loma Prieta quake, the city counted 98 URMs in the state-mandated survey, said chief building official Edward Hamer.
All but a few have been renovated, he said, with the exceptions including some warehouses on Copeland Street, the two-story Silk Mill building on Lakeville Street and a brick wall between two downtown buildings — all currently vacant.
The only URM open to the public is the prized Carnegie Library building, a 1904 neo-classical landmark with a stained glass dome that houses the Petaluma Historical Museum. The city has developed a fix for the building, but needs to find the money for it, which Hamer said could come from a proposed one-cent city sales tax increase on the November ballot.
Petaluma’s URM law does not require a posted warning in an occupied URM, he said.
Steel rods were rarely used in construction prior to 1900, and the first Uniform Building Code was adopted in the western United States in 1927 and in Petaluma six years later, Hamer said. Seismic retrofitting adds bracing, typically inside buildings, but does not bring them up to current code, he said.
Nothing makes bricks any stronger, said Matty Mookerjee, assistant professor of geology at Sonoma State University. Brick tends to crumble under seismic shaking, he said.
Upgrades and conversions
Sonoma, the site of the Bear Flag Revolt in 1846, adopted a mandatory URM upgrade program in 1991 eventually covering 61 buildings. Sixty were either retrofitted or demolished and the last one, added to the list when it changed use in 2011, has been given time to comply, said Wayne Wirick, development services director and building official.
Another Sonoma building, recently converted to a vacation rental and therefore exempted from the program, sustained moderate structural damage in last Sunday’s quake, Wirick said. The rental on the 300 block of First Street West was yellow-tagged, an advisory that allows continued occupation but with a warning — in this case that wall strength had been diminished, Wirick said.
Healdsburg, another city with a historic plaza, identified 14 URMs and has seen 12 retrofitted with another in progress, building official Scott Ward said. Another building is now a single-family residence exempt from upgrade requirements.
There will likely be a “head of steam” to upgrade URMs for a time following last week’s quake, but it’s an expensive process and will eventually return to a low priority, Mookerjee predicted. But they are historic, appealing structures that help define California communities, he said.
“We don’t want to just tear them down.”
Staff Writer Mary Callahan contributed to this report. You can reach Staff Writer Guy Kovner at 521-5457 or firstname.lastname@example.org.