I have been a member of the ANSI A17.1, Earthquake Safety Committee for about 30
years to provide guidance related to earthquake issues. Notwithstanding my long tenure
on the committee, my knowledge of elevators is limited. Following two earthquakes I
have conducted surveys of the elevator maintenance companies to assess elevator
performance. The content of this report reflects my personal views.

Executive Summary
• Elevator damage will probably have less of an impact than items listed below
• Loss of electric power could cause large numbers of elevator occupants to be trapped
and require first responders to remove them from the elevators
• The tripping of seismic switches would require large numbers of elevators to be
inspected by elevator mechanics before being put back into service and cause long
restoration times
• The slow restoration of elevator function in critical facilities, such as hospitals, is a
life-safety issue
• Some measures that could mitigate the effects identified above are discussed

Summary of Past Performance

Injuries in elevators due to earthquakes are extremely rare and can be counted on one’s
fingers. Based on survey reports, damage rates are low with about 200 elevators
damaged in the Loma Prieta earthquake and 700 in the Northridge earthquake. Damage
assessments however, were based on reports from companies that service only about half
of the elevators in the area and completeness of the reports that were received is
questionable. Because damage reports did not indicate details about the cause of the
damage and buildings where damage occurred were not identified, damage could not be
correlated to shaking intensity. Following the 1971 San Fernando earthquake, public
policy changed and damage reports became public documents and could be used by
ambulance chasers resulting in increased liability exposure and a drop in report
submittals. The trapping of people in elevators has not been a documented problem, but
this is probably due to luck and circumstances.

The most common types of significant damage were counterweights coming out of their
guide rails, fouled ropes or governor cables, cable damage to door operating mechanisms,
and movement of equipment or control cabinets. The largest risk of severe injury is when
safety systems are overridden (probably by building engineer) and the elevator put into
service after a counterweight came out of its guides. This can result in the counterweight
striking the elevator cab. (This has happened with unoccupied elevators.)
From an emergency response perspective, the loss of electric power causes the elevator to
stop and trap occupants, which usually requires rescue personnel for extraction.
Demands on elevator mechanics to inspect elevators in buildings with tripped seismic
switches will exceed their ability to respond in a timely manner. Traffic congestion will
exasperate the problem. This will even be a problem for critical facilities, such as
hospitals, that are given high priority for service.