Why a Mormon Mega-Temple is Being Dug-Up

Quick Overview

The Salt Lake Temple is being dug up and retrofitted with a $2 billion base isolation system, involving 98 massive seismic isolators weighing 8,000 kilograms each, to protect the historic structure from major earthquakes along the Wasatch Fault, decoupling the building from ground motion while preserving its original granite and masonry.

Key Points: The Salt Lake Temple is undergoing a $2 billion retrofitting project to protect it from earthquakes along the Wasatch Fault, which could produce a magnitude 7.0 quake. The historic structure is being isolated from ground motion using 98 base isolators, each weighing 8,000 kilograms, installed beneath the original 1800s granite and quartzite foundation. The base isolation system allows the temple structure to move up to 1.5 meters horizontally during seismic activity while maintaining vertical stiffness. The original foundation, which was not built to withstand major quakes, is being undercut by excavating around it and then secured with micropiles and tie-back anchors. The project also includes adding a north addition with a ceiling wing where marriages are performed, increasing seating in instruction rooms. The temple, which took 40 years to build (completed in 1893), is expected to reopen in 2027 due to the complexity of the restoration and seismic upgrade.

Context: The video details the massive, multi-year renovation and seismic retrofit of the Salt Lake Temple, the largest temple of The Church of Jesus Christ of Latter-day Saints, located in Salt Lake City, Utah. The project is necessitated by the building's location near the highly active Wasatch Fault, which poses a significant earthquake risk to the 19th-century structure, originally built without modern seismic standards.

Detailed Analysis

The Salt Lake Temple, the largest LDS temple, is undergoing a massive $2 billion retrofitting project to protect it from potential major earthquakes triggered by the nearby Wasatch Fault (0:03, 1:48). The original temple took over 40 years to build, completed in 1893, using granite and quartzite blocks 9 feet thick (1:17, 1:24). The primary seismic protection involves base isolation, where 98 massive isolators—each weighing 8,000 kilograms—are installed between the original foundation and a new concrete foundation (5:21, 7:11, 7:16). These isolators allow the structure to move up to 1.5 meters horizontally during ground motion, reducing seismic forces transferred to the temple (5:33, 7:24). The construction involves carefully underpinning the existing stone walls by excavating beneath them and installing micropiles and tie-back anchors before pouring the new foundation (5:55, 6:07). The renovation also involves building a North Addition, which will include a new ceiling wing where marriages are performed, and increasing seating capacity in instruction rooms (8:39, 8:41). The entire complex is being modernized to meet current building codes, with the goal of reopening in 2027 (4:50, 14:48). The video contrasts the grid system of Salt Lake City (11:48) with New York City blocks to illustrate the scale of the project (12:42).