Poul-Henning Kamp writes: "There are a number of footnotes about geophones, the primary one being that they have a resonance frequency in the 4-7 Hz range and therefore provide no usable information below that.
The second is that it is anyones guess what their sensitivity is, in particular if you buy it on eBay from somebody who found it lying in a field after percussive oil-exploration, so buy more than one." For something a little more reliable and trustworthy than an eBay gamble, albeit probably more expensive, there is an organisation that caters for people nuts about vibrations - https://raspberryshake.org/ They offer some very nice products and would allow correlation of time glitches from pendulums (an interest of mine), and other clocks, with earthquakes and other such disturbances. John _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
