Earthquake Detector

There has been a resurgence of interest in earthquake detection and prediction recently. If one merely wants sufficient warning to save one's life, this is not difficult. Mostly, P-waves will reach one before S-waves, and if one has a plan, a few seconds may be enough to dive to safety. I have designed a few earthquake detectors (seismometers). Here is the simplest of all, good enough to "do the job". The sensor X1 is made of a round piezo element, here shown from the side. VR1 is a multi-turn preset. The LOAD may be a 12V light or sounder, and the like. Note that IC1 must be CMOS. Mount the detector on a surface that vibrates -- say, a wooden floor -- and adjust as sensitively as it will reliably go.