Patent ID: 7715983

Claim:
A method of detecting hazardous conditions within an underground environment comprising: obtaining acceleration information via an accelerator included in each of a plurality of communication nodes, each of said communication nodes being positioned at known locations throughout the underground environment; propagating the acceleration information among selected ones of the plurality of communication nodes to an analysis node; identifying, from the acceleration information collected over a period of time, an indication of a seismic activity within the underground environment; if a seismic activity is identified, providing a notification of a hazardous condition; interrogating passive radio-frequency identification (RFID) tags associated with persons located within the underground environment at selected ones of the plurality of communication nodes and detecting selected ones of RFID tags that activate in consequence of the interrogation; propagating RFID tag information specifying detected RFID tags among selected ones of the plurality of communication nodes to the analysis node; indicating which persons have been detected by at least one of the communication nodes according to the RFID tag information; including an RFID reader and an RFID tag within each of the plurality of communication nodes; interrogating, via the RFID reader, the RFID tag disposed within that communication node; receiving an identifier of the interrogated RFID tag within the communication node; and propagating the identifier of the communication node to the analysis node as a secondary means of identifying which of the plurality of communication nodes sent transmitted data.