The present disclosure relates to approaches for detecting and monitoring for earthquakes using a control unit of a security system. A security system may include a plurality of sensors that detect alarm conditions and send alarm condition messages to a control unit for the security system. The control unit may be communicatively coupled to the sensors and configured to receive the alarm condition messages from the sensors. The security system may also include an earthquake sensor that senses earthquake conditions and sends an earthquake condition message to the control unit if it detects the earthquake condition. The control unit may include an alarm module. The control unit causes the alarm module to generate an alarm in response to receiving the earthquake condition message from the earthquake sensor.