Now is time for action on temblor risk, rise in sea level

In the mid-1980s, an earthquake brought a temporary halt to an afternoon meeting of the San Diego City Council. As soon as the chambers occupying the top floors of City Hall stopped shaking, council member Bill Cleator bolted from his seat.

He soon returned, explaining he rushed to a window just outside the room to see if the nearly completed Horton Plaza shopping mall was still standing and, he was was happy to report, it was.

Earthquakes aren’t rare in San Diego, though in modern history major ones tend to happen to the north and east. The San Andreas Fault is known around the world; not so with the Rose Canyon Fault.

But there’s newfound respect for, and fear of, the fault system that comes ashore at La Jolla and runs south through downtown San Diego.

For a long time, the Rose Canyon system was thought to be of little risk. In recent years, experts have learned it’s more active, and potentially more destructive and deadly, than previously thought.

Another landscapechanging force is also threatening San Diego.

Like the modest temblors that shook the region over generations, shifting sands and diminishing seaside cliffs have been part of the county’s coastal character. But more attention to climate-change-fueled sea level rise is bringing into focus how much different the coastline may be in the future — and what is built on it.

There are broad ramifications for the coastal region, from the world-renowned beaches and iconic blufftop homes to the San Diego Convention Center and Seaport Village, which is on the brink of a major redevelopment.

Gary Robbins of The San Diego Union-Tribune has chronicled the evolving knowledge about the Rose Canyon Fault threat and what is being done about it.

Geologic experts say the system could generate a magnitude 6.9 earthquake. In March 2020, Robbins wrote about a study by the local chapter of the Earthquake Engineering Research Institute that laid out a scenario most San Diegans probably would rather not think about.

A quake of that size “could damage 100,000 residences, cause widespread road and bridge failures, and make parts of Mission Bay sink about a foot.

“Such a temblor could also cut gas and water service between La Jolla and the Silver Strand for months, collapse key municipal buildings, and close the San Diego-Coronado Bridge.”

That kind of earthquake would cause some $38 billion in building and infrastructure damage, displace 36,000 households — and kill between 1,000 and 2,000 people, according to the study.

The California Geological Survey is now in the process of creating new fault zones “where developers of residential, commercial and public buildings may be required to show that their projects do not sit on top of active faults or are located a safe distance away from such systems,” Robbins wrote in a Feb. 26 article.

The zones will cover some 7,000 parcels and include San Diego International Airport. Nearby

property is proposed for a major transportation hub.

Not far away is the San Diego Convention Center, which some tourism, labor and civic officials still hope to see expanded, despite a narrow loss at the ballot box last year to raise hotel taxes that would provide the funding.

For a decade or more, those plans have been in the works as a string of reports have predicted San Diego Bay will be lapping up to the convention center, or worse. Even now, pumps — officially known as “dewatering facilities” — are bailing out the facility’s underground parking structure.

Whether natural beaches or manmade waterfronts can be fortified or reconfigured to lessen the damage may depend on how high

the ocean rises. That’s a variable, but even at the low end of sea level rise estimates, costs could be significant.

While earthquakes are sudden and unpredictable, sea level rise has the feel of a slow-moving, if inexact, disaster in the making. Yet every collapsed bluff and extreme King Tide reminds us it’s coming.

Potential sea level rise losses also are hard to grasp.

A report by the California Legislative Analyst’s Office released in August said the ocean could rise by 6 feet or more in some areas by 2100, wiping away twothirds of Southern California’s beaches.

Deborah Sullivan Brennan of the Union-Tribune noted that a rise of 3 feet, combined with a 100-year storm “could harm 830 businesses and threaten 15,000 jobs and $2 billion in

property sales. At 6 feet of sea level rise, a 100-year storm could damage 2,600 businesses, and affect 49,000 jobs and $8 billion in sales.”

Sure, these earthquake and sea level scenarios can seem hopeless, but doom isn’t inevitable — if we squarely face the realities and move to adapt to them.

From Sacramento to San Diego, state and local governments have empaneled committees to not just study sea level rise but look for solutions, or, rather, workarounds. A lot of the focus has been on protecting, or moving, public infrastructure, but tackling the 800-pound gorilla of private property will take some doing.

For example, the land for the Chula Vista Bayfront project was elevated in anticipation of rising waters. But some coastal cities have run into heated opposition just trying to start a conversation with property owners about “managed retreat” from threatened coastal areas.

Greater understanding of earthquakes along with technological advances have led to the construction and retrofitting of buildings able to withstand strong temblors that would have knocked down lesser structures generations ago. But a lot of that knowledge came from hard lessons learned — after the fact — from devastating earthquakes.

Getting ahead of the curve by taking expensive and politically difficult pre-emptive action is not something government does particularly well, whether it involves the moving Earth, rising seas or, as we have seen, even a deadly pandemic.

The San Diego Union-Tribune, P.O. Box 120191, San Diego, CA 92112-0191