During earthquakes, buildings typically sustain damage by ground accelerations or subsequent fires and explosions caused by leaking gas (i.e., resulting from broken gas pipelines). Older buildings are particularly susceptible to structural damage caused by ground accelerations, and so seismic sensors are sometimes used to increase the safety of vertical transportation equipment (VTE), such as elevators, in service within such vulnerable buildings. These seismic sensors are intended to detect seismic accelerations exceeding safety guidelines and thereafter safely shut down the VTE. In this regard, U.S. Pat. Nos. 5,760,696, 5,929,767, 6,265,979, and U.S. Patent Application Publication No. U.S. 2011/0249530 are each hereby incorporated by reference in its entirety.
In a conventional seismic unit, an accelerometer typically provides output data (e.g., voltages) that the seismic unit's microcontroller uses to determine the appropriate action in response to a seismic event. An accelerometer, however, may provide inaccurate readings and fail outright, rendering the conventional seismic unit ineffective in response to a seismic event. This can jeopardize the safety and health of building occupants.