A device is provided for monitoring a geological region or a structure. The device includes: a sensor, a radio transmitter configured to transmit data obtained by the sensor, a power source configured to power the sensor and/or radio transmitter, and a housing configured to protect the power source, radio transmitter and optionally the sensor. The sensor is capable of sensing a parameter useful in determining movement within a geological region or a structure; and/or the potential for failure in a geological region or a structure. The devices may include several sensor types capable of sensing parameters such as strain, pressure, temperature, electrical conductivity, electrical resistance, or chemistry. A series of devices may be operable as a system, with at least some of the devices further functioning to relay radio signals transmitted by other devices of the system.