Minimal quake damage seen in Petaluma (audio of the Aug. 24 quake)

When the fire station on D Street began shaking early Sunday morning, Battalion Chief Jeff Holden had one thought on his mind: get the main doors open.

“We don’t want those doors to get twisted shut so we can’t get our equipment out,” explained Petaluma Fire Chief Larry Anderson. “He (Holden) headed straight to the doors while the quake was still going.”

The magnitude 6.0 earthquake rocked Napa, Vallejo and American Canyon, caused more than 200 injuries and damanges estimated at $1 billion. But Petaluma was largely unscathed aside from a few cracked cinder blocks at the Salvation Army building and reports of items being rattled off shelves.

Anderson said the city’s emergency response protocols “went off without a hitch.” He was on the phone with City Manager John Brown and Police Chief Patrick Williams within five minutes of the quake to coordinate the effort. As soon as they realized Petaluma was only minimally impacted, they offered their services to Napa. Public Works Director Dan St. John said a city engineer was able to monitor Petaluma’s critical infrastructure, including water mains, from his computer following the disaster.

“He could tell within seconds if there was a problem,” St. John said, adding that no issues were detected on Sunday.

Local emergency dispatchers were flooded with calls, some related to medical incidents, but in the hour following the quake, 16 people called 911 just seeking information. Anderson emphasized the importance of only contacting emergency services when help is needed, especially during a disaster.

“Anything less than a true emergency dilutes our response,” Anderson said. “The inquiries can be directed to USGS (United States Geological Survey), which updates its website instantly.”

It is fire, not earthquakes, that poses the biggest threat to Petaluma’s historic downtown. The 4-inch cast iron water main that runs beneath Petaluma Boulevard between Kent and B Street is 75 to 100 years old and too small to allow area businesses to tap for fire prevention sprinkler systems, leaving some buildings at risk.

“There are a significant number of buildings that can’t get sprinklers until a major water line is installed,” Anderson said.

The city has plans to replace the inadequate pipe with 12-inch PVC piping, a $4.8 million project that is expected to take two years and is slated to begin in 2016. St. John said the new pipeline will better survive a quake, largely because it includes modern joints that are less likely to snap during a seismic event.

With much of its historic downtown made from wood-frame structures and masonry, Petaluma has depended on private property owners to do the costly seismic retrofits needed to protect buildings from future quakes. In 1975, Skip Sommer purchased Petaluma’s oldest standing commercial building, the Great Mill, and hired a restoration architect to find ways to reinforce the 54,000-sqaure-foot building with steel beams so that it could stand up to a magnitude 8.4 earthquake while still maintaining its unique character.

“You can do the seismic upgrades and still make it looking charming,” he said, while admitting it can be costly. He spent $350,000 on the retrofit in 1975, which would be about $1.57 million in today’s dollars.

Brown said “most” of the city’s unreinforced masonry buildings have been seismically upgraded, and many of the wooden structures have been reinforced with steel beams. City officials agreed that while the city is well-prepared for an earthquake, individual households and neighborhoods should prepare as well.

“As we learned this weekend, stuff happens; these are radical events,” said St. John. “You have to prepare yourself as best you can.”