Abstract: A seismic sensor 10 comprises an acceleration acquisition unit 21, an acceleration waveform generation unit 22, a frequency sensing unit 24, and an earthquake determination unit 25. The acceleration acquisition unit 21 detects vibration and measures the acceleration of the vibration. The acceleration waveform generation unit 22 generates an acceleration waveform that indicates the relation between the elapsed time and the acceleration measured by the acceleration acquisition unit 21. The frequency sensing unit 24 senses the frequency of the acceleration waveform generated by the acceleration waveform generation unit 22 using a zero-crossing method. The earthquake determination unit 25 determines whether or not there is an earthquake on the basis of the frequency sensed by the frequency sensing unit 24.

Abstract: A seismic sensor 10 comprises an acceleration acquisition unit 21, an acceleration waveform generation unit 22, a frequency sensing unit 24, and an earthquake determination unit 25. The acceleration acquisition unit 21 detects vibration and measures the acceleration of the vibration. The acceleration waveform generation unit 22 generates an acceleration waveform that indicates the relation between the elapsed time and the acceleration measured by the acceleration acquisition unit 21. The frequency sensing unit 24 senses the frequency of the acceleration waveform generated by the acceleration waveform generation unit 22. The earthquake determination unit 25 determines whether or not there is an earthquake by classifying acceleration waveforms into those in which the frequency sensed by the frequency sensing unit 24 is above a specific threshold and those in which the frequency is below the specific threshold, and excluding any acceleration waveforms in which the frequency is above the specific threshold.

Abstract: A seismic sensor may include a simple earthquake detection mode in which measured acceleration data is not saved, and which mode is continued in a case in which the measured acceleration is equal to or less than a predetermined first threshold value. An earthquake detection mode may further be included in which the measured acceleration data is saved, and which mode is continued in a case in which the acceleration measured in the simple earthquake detection mode is greater than the first threshold value and equal to or less than a second threshold value that is greater than the first threshold value. An earthquake measurement mode may further be included in which the acceleration data and a spectrum intensity (SI) value are measured and saved, and which mode is continued in a case in which the acceleration measured in the earthquake detection mode is greater than the second threshold value.

Abstract: A seismic sensor may include a simple earthquake detection mode in which measured acceleration data is not saved, and which mode is continued in a case in which the measured acceleration is equal to or less than a predetermined first threshold value. An earthquake detection mode may further be included in which the measured acceleration data is saved, and which mode is continued in a case in which the acceleration measured in the simple earthquake detection mode is greater than the first threshold value and equal to or less than a second threshold value that is greater than the first threshold value. An earthquake measurement mode may further be included in which the acceleration data and a spectrum intensity (SI) value are measured and saved, and which mode is continued in a case in which the acceleration measured in the earthquake detection mode is greater than the second threshold value.