Described herein is method for the detection of seismic activity using a network of lights, and in particular, street lights (43) arranged over a number of streets (42). Each light includes a control module having the facility for both long- and short-distance communication, the control modules being grouped with other control modules and associated with a group controller to create a short-distance or mesh network. Each control module includes a sensor which is capable of detecting seismic activity and data relating to such activity may be transmitted to a central server via its group controller using long-distance communication. Even if the sensors are relatively inaccurate, the high number of such sensors present in the network makes it possible to detect and analyze the activity using geocoordinate information provided by the control modules at the server. Information relating to an epicentre of an earthquake can be determined and distributed to control modules in the vicinity of the detected seismic activity (50) to provide warning light signals for the population in that vicinity.