Commercial elevators in Earthquake zones have safety sensors installed with the elevator to cause an automatic shutdown, in case an earthquake hits.
As you might have read a month ago, Baja California in Mexico experienced a 7.2 magnitude earthquake and this traveled up through Southern California. Many elevators, as a result, shut down automatically from sensors added to the system. Many elevators in Southern California had slowed or stopped service when this recent earthquake hit, as buildings with elevators in this area are equipped with two earthquake sensors.
According to the article linked above, nearly all buildings in Southern California have these two sensors, which include a seismic reader and a thin wire that travels the length of the elevator shaft. If the seismometer senses any movement or if the wire moves, the circuit trips, and the elevator stops working automatically. When the earthquake hit, many elevators stopped, some with people inside, and, in Los Angeles, the fire department had to free those stuck inside elevator cabs.
As mentioned in the article, elevators that shut down in California need to be inspected first and the sensors reset before they start running again. Nevertheless, if the elevators weren’t equipped with these sensors, more damage and injuries would probably result.
Home elevators move at a much slower speed than commercial elevators, so they do not require seismic sensors. However, most residential elevators such as the Freedom 750 have safeties that will stop the elevator if the house shifts due to earthquake. For instance, there are brakes that instantaneously stop the cab if there is slack in the cable. An electric switch senses if the brakes are applied, and shuts down the elevator. For hydraulic elevators, there is a flow control valve that will never allow the cab to overspeed, even if a pipe bursts. Unlike commercial elevators, home elevators allow for manual exit from the cab if the elevator shuts down. All elevators should have a phone installed in the cab for emergency purposes.