In 1971 a magnitude-6.6 earthquake in San Fernando caused some damage to the Caltech campus. Engineers who evaluated the damage found that two historic buildings dating from the early days of the Institute—Throop Hall and the Goodhue-designed Culbertson Auditorium—had cracked. These were some of the first reinforced concrete buildings, and their plans did not contain enough details (such as how much reinforcing bar had been embedded in the concrete) to be sure they were safe, so the engineers recommended demolition. However, demolishing these historic structures required considerably more effort than would have been necessary had they been in real danger of collapse. A large wrecking ball was used to demolish Throop Hall, and smashing the concrete revealed massive amounts of rebar, far in excess of safety requirements. The rebar had to be cut up before the pieces could be hauled away, and the process took much longer than expected.