Abstract: An earthquake determination system which includes a plurality of observation terminal devices are connected by a communication network. When estimated P-wave detection information is received from the plurality of the observation terminal devices, a distance D between the observation terminal devices and a time interval ? between detection times are acquired and when transmission limit distance of local vibration energy is DSL, the minimum propagation speed of the earthquake P waves is SP, and the maximum detection error between detection times by the pair of observation terminal devices is ?t, the seismic analysis processor determines occurrence of an earthquake, if the both of the two pairs of the observation terminal devices satisfy the relationships of 2DSL<D and ?<D/SP+?t.

Abstract: An earthquake determination system which includes a plurality of observation terminal devices are connected by a communication network. When estimated P-wave detection information is received from the plurality of the observation terminal devices, a distance D between the observation terminal devices and a time interval ? between detection times are acquired and when transmission limit distance of local vibration energy is DSL, the minimum propagation speed of the earthquake P waves is SP, and the maximum detection error between detection times by the pair of observation terminal devices is ?t, the seismic analysis processor determines occurrence of an earthquake, if the both of the two pairs of the observation terminal devices satisfy the relationships of 2DSL<D and ?<D/SP+?t.