Seismic sensor and earthquake determination method

Abstract

Erroneous determination of noise as an earthquake is reduced in a seismic sensor. The seismic sensor operates in a power saving mode and a measurement mode in which power consumption is larger than that in the power saving mode. The seismic sensor includes: a measurement unit configured to measure acceleration; an earthquake determinator configured to transition from the power saving mode to the measurement mode when the acceleration measured by the measurement unit exceeds a predetermined threshold, to determine whether an earthquake is generated based on the acceleration measured in the measurement mode; and an index calculator configured to calculate an index value indicating a scale of the earthquake when the earthquake determinator determines that the earthquake is generated. The earthquake determinator determines whether the earthquake is generated by determining whether a predetermined condition is satisfied, the predetermined condition being determined based on the acceleration measured in at least one determination period, each determination period into which a period after the power saving mode transitions to the measurement mode is divided being set to a processing unit, and the measurement mode transitions to the power saving mode when the earthquake determinator determines that the earthquake is not generated.