Sherlock Investigates: Seismic Signals Below 1 Hz

With earthquakes making big news recently, our intrepid electronics detective shows you how to build a receiver to pick up signals generated by tectonic activity and have your own home seismometer.

“SHERLOCK”

Very low frequency seismic signals (below 1 Hz) can be detected from earthquakes around the world. The detector (receiver) in Photo A is in the corner of my basement to keep it isolated from local seismic noises. Local noises from trucks, trains and windblown trees cause seismic pollution mainly above 1 Hz. The frequency of this detector is 0.25 Hz (which is period of 4 seconds), which is good for filtering out local noise and for detecting earthquakes. The equipment needed to detect these signals is a detector, a DC amplifier and a recorder (Photo B). The detector is a swinging ‘garden gate.’ It is literally a swinging gate 3 feet long, hanging on a nail point and swinging at the base on a knife edge to eliminate friction. The…

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CQ Amateur Radio (Digital) - 1 Issue, April 2023

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