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SALT LAKE CITY — Construction crews at the Salt Lake Temple have reached an earth-shaking milestone — literally.
Several years of seismic reinforcement work at the Salt Lake Temple culminated with the successful placement of the structure onto its new base isolator system on June 25 when the renovation team removed 392 plates that had been connected to the 98 temple’s base isolators. More than 1,500 connecting bolts were removed as part of this task. The plates had previously been put in place to stabilize the base isolators during installation and amid the transfer of the temple’s weight.
The removal of the supporting plates marks the full completion of seismic work on the Salt Lake Temple renovation. Exhaustive seismic reinforcements were a central aim of the renovation project, which has been ongoing since January 2020 under the direction of Jacobsen Construction as general contractor.
“This is a milestone moment for this whole project,” Brad Bohne, general superintendent with Jacobsen Construction, said in a release published by the Church Newsroom. “The temple is set free. Free to move now during an earthquake, so a big deal for us.”
The seismic reinforcement of the 198-million-pound Salt Lake Temple has required numerous custom-engineered solutions. These have included wrapping massive new concrete transfer girders entirely around the foundation, installing and post-tension strengthening steel pipes under the original temple foundation, pumping voids in the original stone with high-strength grout, performing coring through the temple columns and walls to make room for reinforcing vertical steel cables, adding new steel trusses to the roof, strengthening all six temple spires with new steel supports — and, crucially, installing 98 base isolators to allow the temple to move with the ground in an earthquake without sustaining damage.
“The system is unlike anywhere else in the world,” said Nathan Espinoza, assistant project manager with Jacobsen, referring to the project’s thorough base isolation methods and other seismic innovations.
Base isolators are sophisticated mechanical devices that support a steel plate platform capable of moving five feet in any lateral direction during an earthquake, which gives the building enough flexibility to withstand severe seismic activity without breaking away from its foundation. The steel plate moves with the building and keeps the weight of the building supported, while also staying securely attached to the base of the device.
When the seismic activity stops, the weight-bearing steel plate comes to a natural rest back in its original position sitting atop the bottom-center of the dish-shaped foundation of the isolator.
“That way, the building can do whatever it has to do during the seismic event and settle back in exactly where it’s supposed to be,” explained Brandan Rowley, superintendent with Jacobsen, when the first base isolator was installed under the temple in 2023.
A large majority of Utah’s population lives in proximity to the Wasatch Fault, a fracture in the earth’s crust that runs through Weber, Davis, Salt Lake and Utah counties. This fact has driven exhaustive preparation efforts in the state over the past half-century, including upgraded seismic standards for all newly constructed buildings starting in the 1970s and the participation of nearly a million people in the annual Great Utah Shakeout practice drill since it was first launched in 2012. The Salt Lake Temple was originally completed in 1893, long before modern earthquake protection methods were developed, and seismically strengthening the iconic structure has been one of the central goals of the renovation.
Other aspects of the renovation have included adding a baptistry and other religious ordinance spaces that increase the temple’s capacity, building a new adjacent Visitors’ Center, carefully renovating the interiors by restoring and installing specially tailored finishes, and beautifying and refreshing the whole Temple Square campus.
The Salt Lake Temple is Utah’s most well-known building and is held sacred as a symbol of religious devotion for millions of members of The Church of Jesus Christ of Latter-day Saints around the world, who consider specially dedicated temples to be the holiest places on earth.
Prior to its rededication, the Salt Lake Temple will welcome large numbers of visitors of all faiths, and from all across the globe,
during an open house period from April to October 2027.
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Article cover photo: Church Newsroom