When the big one hits, Congregation Sherith Israel will be ready. Last month, the venerable — and formerly vulnerable — San Francisco congregation completed its massive seven-year, $16 million seismic retrofit.

Constructed in 1905, the congregation’s building survived the great earthquake and fire of 1906, suffering only minimal damage. As it was the city’s largest assembly hall still standing, Sherith Israel’s grand sanctuary hosted San Francisco’s courts for 18 months.

Eighty-three years later, Sherith Israel withstood the 1989 Loma Prieta earthquake. But as a result of that earthquake and its impact on the nearby Marina District, where four people lost their lives and 124 buildings were damaged or collapsed, San Francisco tightened its codes on unreinforced masonry buildings.

Sherith Israel, founded in 1851 and one of the oldest synagogues in the West, had to comply.

“This retrofit will ensure that Sherith Israel will continue to be in the Jewish community for generations to come,” said congregational president Craig Etlin. “We were really facing an existential threat. If we were not able to retrofit this building, the city would have shut it down.”

To commemorate the conclusion of the retrofit, the congregation will be holding a special Shabbat service on Friday, June 9, which will include “extra-special music” and an “extra-nice catered oneg,” Etlin said. “We have [historian] Fred Rosenbaum of Lehrhaus Judaica speaking to us about the history of the congregation and building,” he said.

The shul, indeed, has a rich history: last year, JTA named Sherith Israel as one of nine iconic sites celebrating American Jewish history.

One of the most innovative aspects of the retrofit was the installation of a tension-tie system, located in the building’s attic. Made of a material called nitinol — a nickel-titanium alloy — the tie-in system will prevent the walls from falling outward in case of a major earthquake. “It’s a very high-tech solution in the building,” Etlin said.

During the first of the two phases of construction, starting in 2010, the shul drilled vertical and horizontal holes in the masonry walls and added steel reinforcement, among other measures.

“The primary work was what’s called center coring,” Etlin said. “There’s a sandstone exterior, but behind that are red bricks, many, many widths deep. Up at the top of the roof walls, we cut out a portion and bored down all the way to the foundation and put in steel rebar. Around the rebar we poured a vinyl grout.”

The seismic improvements arrive as researchers at the U.S. Geological Survey have updated their forecast for the potential for quakes. Scientists now say there is a 72 percent probability there will be one quake above magnitude 6.7 somewhere in the Bay Area before 2043.

The solar panels speak to our values. They help us protect the environment and the city around us.

Though USGS and other researchers believe that the Hayward fault is the most likely location, any big earthquake would likely be felt throughout the region. The Loma Prieta quake originated in the Santa Cruz Mountains, more than 50 miles from San Francisco.

Even though Sherith Israel’s retrofit was necessary, it wasn’t an easy job to complete. Planning started in 2000; members of the congregation, roughly 600 households, donated $8 million toward the $16 million project, according to a synagogue press release. Another $5 million came from the shul’s cemetery, Hills of Eternity, the release said, and the remainder came from local foundations and philanthropists, including the Koret Foundation, the Hellman Family Foundation, the Bernard Osher Foundation, the Laszlo N. Tauber Family Foundation and the Richard and Rhoda Goldman Foundation. A campaign is underway to raise the remaining $1.3 million, the release added.

In addition to the retrofit, the shul made other improvements to the building, such as accessibility upgrades that comply with the Americans with Disabilities Act. The project also included installing rooftop solar panels, which will power about half of the building’s electrical needs, according to Etlin.

“The solar panels speak to our values,” said Rabbi Jessica Zimmerman Graf, senior rabbi at Sherith Israel. “They help us protect the environment and the city around us.”

For their part, congregants believe that the completed project demonstrates that the shul will continue to play an important role in the community.

Board member Amy Mains said the completion of this project “shows the longevity of Sherith Israel. It demonstrates investment in institutions that have survived earthquakes and politics over the decades … What it says, in a city of changing jobs and industries, is that Sherith Israel is still here and will be in the future.”