What happens when the earth moves?

At Sensors Expo 2019, Satya Dixit from Applications and Systems Engineering at Rohm Semiconductor explains the capabilities and applications for an earthquake sensor module. The earthquake detection module (BP3901) has correctly detected 200 out of 205 previous cases of seismic events.

Waveform differences between a seismic event and an external event such as a collision allow correct identification of each by an earthquake detection algorithm built into the microcontroller with the accelerometer mounted in close proximity. The 11.8 x 8.6 x 2.5-mm BP3901 module provides earthquake sensitivity through an I²C interface. The demo indicates the presence or absence of an earthquake event. Unlike mechanical earthquake detectors that only detect the presence or absence of vibration, the waveform analysis capabilities of the BP3901 allow it to distinguish between an actual earthquake and an external, non-seismic vibration. An angle correction function (±15° allowable mounting angle) can correct for unintentional tilt of the module to further improve its detection accuracy.

The three-axis accelerometer in the module is from Rohm’s Kionix division. Its microelectromechanical systems (MEMS) design contributes to the small size of the BP3901.

Applications for earthquake detection include utility meters, warehouses, bridges and locations where knowledge of an earthquake can initiate an action to prevent avoidable secondary damage due to the earthquake. This could include shutting down a gas pipeline or stopping a chemical flow. In earthquake prone regions, the earthquake detection module is installed in a smart utility meter, on top of a traffic light or in other critical areas or zones where preventative actions can be initiated.