What if the ‘Big One’ Hits the North Bay?

(TNS) – The ground jerks violently, shudders and rocks, cracking walls and blowing out windows.

Roadways rupture. Water lines break. Homes and buildings slide off their foundations. Some topple completely.

There are people trapped in collapsed structures, a high number of injuries and fatalities, as well. Thousands lose shelter, and many others endure days and weeks without water, power, phone service and data communications. Hospital and medical resources are stressed to their breaking point.

Regular life comes to an abrupt halt, and a new kind of existence begins amid a desperate, surreal reckoning with reality.

As volunteers and loved ones comb through the rubble of the catastrophic pair of earthquakes that have claimed more than 20,000 lives in southern Turkey and the northern reaches of Syria, the scenes seem entirely foreign and remote — a horrifying, unimaginable state of affairs.

But could the unimaginable happen here?

And it’s not a matter of if, but when, seismologists say.

And even though scenes from the North Bay in the wake of a disastrous quake would look somewhat different — fewer pancaked high-rise apartment buildings and less crumbled, unreinforced concrete, for example — the potential for loss and suffering is profound.

“We should not be smug and say, ‘Oh, what happened in Turkey couldn’t happen to us,'” said well-known seismologist and Caltech adviser Lucy Jones, formerly with the U.S. Geological Survey and later science adviser for seismic safety to the city of Los Angeles. “I do think do think we are not suffering from the problems at the same scale that they are suffering them, but in kind, all of those issues apply here.”

The 7.8- and 7.5-magnitude quakes that have drawn the world’s attention to Turkey were made worse because they emanated from relatively shallow centers, experts say.

Observers have also pointed to substandard building codes and enforcement as factors in the widespread loss of infrastructure, leaving many thousands homeless.

California building codes are stronger, but they are mainly fashioned around a “life-safety standard” that is intended to prevent collapse, Jones said, but may nonetheless result in infrastructure loss.

A recent FEMA report predicted 20% to 40% of code-conforming buildings in an affected area would be unfit for occupancy after a large earthquake, while 15% to 20% would be too badly damaged to repair.

With most residents uninsured for earthquake losses, a major quake in the area “will be very challenging,” Sonoma County Emergency Management Director Chris Godley said.

“It’s going to be a significant trauma to the community, one we’ve not experienced in our living memory,” he said.

California and the Bay Area are threaded with active fault lines, including the recently triggered Rodgers Creek Fault that cuts right through Santa Rosa and put residents on edge last September with paired 4.4 and 4.3-magnitude temblors.

To the west, along the Sonoma Coast, the mighty San Andreas Fault lies in wait, its history of major, damaging ruptures part of many Californians’ history.

Running most of the length of the state, it famously caused the 1906 San Francisco Earthquake, magnitude 7.8, and, perhaps less notoriously, triggered the 7.9-magnitude Fort Tejon quake in 1857, which was centered near Parkfield, in Monterey County, and caused fissures and displacement for more than 100 miles to the south.

For comparison, the 1989 Loma Prieta quake, centered outside major urban areas in the Santa Cruz mountains, was magnitude 6.9. It killed 63 people across a wide range and caused up to $10 billion in property loss, according to the USGS.

The Monday morning quakes in Turkey measured 7.8 and 7.5 respectfully, many times more powerful than Loma Prieta.

Each full point represents a 10-fold increase in energy released, so the 7.8 was nearly 10 times the severity of a the 1989 California quake.

For its length and position on a major boundary between the Pacific and the North American plates, it is perhaps most analogous to the Anatolian Fault system that shifted in Turkey with such cataclysmic results earlier this week, USGS research geologist Suzanne Hecker said.

The San Andreas also has an extremely high slip rate — meaning the comparative rates at which the two adjoining plates are traveling is high.

But the Rodgers Creek Fault, recently confirmed to be connected to the Hayward Fault so they are virtually the same, 118-mile-long fault line, is considered capable of a significant quake of magnitude 7.4.

But there are lesser known and unknown faults that also could rupture, such as happened with the 2014 Napa quake, a magnitude 6 shaker that occurred on the West Napa Fault.

Seismologists put the overall probability of an earthquake measuring magnitude 6.7 or greater in the San Francisco Bay Region at 72% during the 30-year period from 2014 to 2043 — with the Rodgers Creek-Hayward system that runs right through Santa Rosa past Healdsburg the most likely host, though the iconic San Andreas fault has produced the largest earthquakes historically.

For Jones, the issue of 30-year probabilities, established mainly because most mortgages are 30-year ones, obscures the inevitability of a major quake at some point and some place unknown in the region.

Whether it reaches 7.8 or something less, “7.0 or higher in the next 30 years is a really big bleeping earthquake,” said Neil Bregman, emergency preparedness manager for Santa Rosa.

Silty, soft soils across the Santa Rosa Plain and in much of Sonoma County raise the likelihood of liquefaction and mudslides and would likely amplify the impact of seismic waves, as they did in 1906, when Santa Rosa suffered casualties and property losses disproportionate to its population and proximity to the epicenter.

The city and county have both worked to develop emergency plans and operational protocols that foresee some of the worst that could happen given the inevitability of a major quake — whenever that happens.

It’s not, said Godley, “going to get republished by the tourist board.”

But it should be enough to encourage people to prepare to be on their own for days, before help can arrive, stocking water and food in emergency kits and considering seismic upgrades, particularly for older buildings.

Where possible, folks should consider leaving the area if the big one comes, Bregman said, “if you have the resources and budget.”

“Every minute you can buy us in being prepared is a minute we can help someone else,” Bregman said.

©023 The Press Democrat (Santa Rosa, Calif.). Distributed by Tribune Content Agency, LLC.