| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve responsiveness and reduce manufacture cost by detecting a P-wave and regulating its previously set threshold value level with a potentiometer, etc. SOLUTION: An earthquake detector A has an outside protection vessel 10 mounting a voice alarm, and a control knob 14 is set together with a control knob 16 serving as an ON-OFF switch. A P-wave, i.e., a first motion can be detected with the earthquake detector A, which has a piezoelectric converter for generating a P-wave electric signal in response thereto. In addition, a threshold value level is regulated with a potentiometer. In a case where the P-wave exceeds the previously set threshold value level, a voice alarm is generated. The P-wave of the first motion transmits at the speed of two times larger than s-wave of the second motion. Thus, each individual has a chance capable of taking refuge from a risk place before arrival of the more destructive s-wave by giving the alarm informing the arrival of the s-wave approaching instantly.</p> |
