FAIRFIELD — Solano County got a small but sharp reminder Oct. 8 that this is earthquake country.
A quake that registered 3.2 on the Richter scale hit central Solano County. No one got hurt and no damage was reported, but local residents certainly felt the shaking.
“Within the first quarter-of-a-second, you thought your house was hit by something,” Suisun City Councilwoman and Old Town resident Jane Day said shortly after the event.
No big deal, but a warning that the “Big One” could happen here.
The Concord-Green Valley fault is capable of far, far bigger quakes. According to the U.S. Geological Survey, there’s a 4 percent chance it could generate a quake of a magnitude of 6.7 or greater in the next 30 years. That’s a quake on the scale of the one that toppled buildings and freeways in Northridge in 1994.
Monster quakes on the Concord-Green Valley fault are hardly an everyday occurrence, at least by human rather than geological standards. The last large quake occurred between 200 and 500 years ago, a U.S. Geological Survey report said.
Still, the Association of Bay Area Government’s “On Shaky Ground” project makes it clear that a big Concord-Green Valley quake could cause big local damage. The report includes earthquake maps that show where the devastation would be greatest under various earthquake scenarios.
A 6.7 quake along the Concord-Green Valley fault would cause violent shaking in areas such as Cordelia and Suisun City’s Old Town. Chimneys could fall, frame houses could fall off their foundations if not bolted down, underground pipes could break and some stucco and masonry walls could fall.
And, of course, people could be hurt. Thursday’s earthquake drill scenes could become reality.
Suisun City’s Old Town and the downtown Fairfield areas are particularly vulnerable to big quakes, according to the “On Shaky Ground” studies. That is because the marshy soils there amplify shaking.
Solano County has more faults than the Concord-Green Valley fault, though that is the most notorious one. Others include the Cordelia fault near Rockville, the Kirby Hill and Montezuma Hills faults near the Montezuma Hills and the Vaca fault near Vacaville.
There’s proof the “Big One” can hit here. It did, on April 19, 1882, not along the Concord-Green Valley fault, but along a fault north of Vacaville. The estimated magnitude was 6.4 to 6.7, enough to crumble brick buildings in Vacaville, Dixon and Winters.
“Main Street was the scene of destruction and confusion, littered from one end to the other with bricks, plaster and wires,” wrote an observer in Vacaville. “The town presented the appearance of a prairie village after the passage of a cyclone.”
Pioneer Williams Pleasants lived in the rural valley bearing his family name north of Vacaville. He wrote about the quake in his journal.
“All chimneys were shaken off even with the house, tops plastering was torn off of houses and houses wrenched from their foundations,” Pleasants wrote.
“My house swayed about three feet from west to east. The shock was preceded by a low rumbling noise in the mountains west of the valley which quickly approached with a heavy shaking and upheaving. The rumbling noise sounded like a carriage driven quickly across a bridge.
“Winters is living in tents. So are a great many people in the country living in tents. The governor furnished the tents.”
Pleasants himself went to Winters to get one of the government-issued tents. The aftershocks lasted for weeks.
That’s Solano County’s past. Given the area’s many faults, it could also be its future.
Reach Barry Eberling at 427-6929 or firstname.lastname@example.org. Follow him on Twitter at www.twitter.com/beberlingdr.