Salt Lake City ? The state Capitol is being elevated a fraction of an inch so that engineers can install a “shock absorber” to cushion the 67,500-ton building against earthquakes up to magnitude 7.3.

Salt Lake Valley is due for a magnitude 7 earthquake. In preparation, workers will install 280 rubber-and-steel mounts under the Capitol’s footings to bolster the building in case of such a scenario.

Officials working on the project say the “seismic base isolators” will allow the Capitol to sway and list as it absorbs the shock of an earthquake.

“The most complicated part of the project was … lifting the building so we can cut off existing columns and remove foundations, which will be replaced with a new foundation and the seismic base isolators,” said Parry Brown, a partner for Salt Lake’s Reaveley Engineers & Associates.

The hoisting will take another 20 months, said architect David Hart, executive director for the Capitol Preservation Board, the organization overseeing every aspect of the $212 million project.

The Capitol, which is closed, is expected to be ready for occupancy again by January 2008. Gov. Jon Huntsman, his executive staffs and the part-time Legislature will move back in from a pair of Capitol wings constructed as part of the renovation plan.

The Utah Capitol was made of concrete and marble finished in 1912 with almost no reinforcing steel, forcing engineers to devise a new, rigid framework and interior walls that will hold it up.

Workers clear debris and rubble from the job site as part of the earthquake proofing renovation at the Utah Capitol in Salt Lake City. The entire building is being lifted so a new foundation can be installed that will cushion the building during an earthquake.

Engineers planned several precautions as workers excavated the Capitol’s foundation and cut into its concrete footings. First, workers had to inject grout at high pressure into the rocky, granular soil under the footings. They are laboriously cutting into each footing in a 14-step, staggered process to ensure support remains for the building, a smaller version of the U.S. Capitol.

Brown said earthquakes occur randomly, but the Salt Lake City segment of the Wasatch fault historically has seen large earthquakes every 1,250 to 1,300 years.

“The last one recorded geologically with dating techniques was 1,250 to 1,300 years ago,” he said.