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Actual seismograph electronics are very expensive. I'm just wondering if a seismograph can be made with a adequately semsitive accelerometer. To be exact I want to bury the accelerometer based seismograph and have it sense footsteps.

So is this possible and what method would you reccommend for my needs and why?

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  • \$\begingroup\$ Either a) calculate the expected acceleration and compare it to specs (including noise) or b) get an acceleromater breakout and hang it off something like an Arduino that can stream data to a PC for analysis and see what you get. \$\endgroup\$ – Chris Stratton Jul 12 '19 at 19:24
  • \$\begingroup\$ A seismograph is an adequately sensitive accelerometer. Or perhaps "appropriately sensitive" is a better term. So -- yes, absolutely. There. Done with that question! Questions about which sensors to choose for a particular task are probably better directed to engineering.stackexchange.com -- this would be the group to ask if you have a sensor in hand and want to build electronics that work with it. I suggest closing this question and asking "what accelerometer or microphone characteristics do I need to sense footsteps"? \$\endgroup\$ – TimWescott Jul 12 '19 at 19:24
  • \$\begingroup\$ @TimWescott Lol thank you for your straightforward answer. \$\endgroup\$ – Steve Mucci Jul 12 '19 at 19:38
  • \$\begingroup\$ A better thing to detect footsteps might be a microphone \$\endgroup\$ – Voltage Spike Jul 12 '19 at 23:10
  • \$\begingroup\$ The magazine Scientific American had a column "The Amateur Scientist" that showed the building of a seismograph. \$\endgroup\$ – analogsystemsrf Jul 17 '19 at 6:13
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Many MEM's accelerators have a frequency response like this:

enter image description here Source: https://www.analog.com/en/analog-dialogue/articles/choosing-the-most-suitable-accelerometer-for-your-application-part-2.html

Which is most responsive after 1kHz. Earthquakes have frequency response of less than 20Hz. This means most cheap accelerometers will not be able to detect earthquakes well as the signal will be very low and the MEM's accelerator won't be able to respond to most small earthquakes (big ones are another matter).

As far as footsteps go, most floors have a long wavelength (think floor joists) and also have low frequencies, cement floors would be very hard to pick up on vibrations from footsteps. Microphones probably wouldn't have too hard of a time however, but also pick up much more noise.

A peizo electric floor mat might be a good way to go also.

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  • \$\begingroup\$ While there might be a higher response at certain frequencies, keep in mind that the typical applications of MEMS accelerometers are to detect very low frequency changes or even steady state conditions. The asker should calculate the expect acceleration and compare to the sensitivity specs; or simply try the experiment. \$\endgroup\$ – Chris Stratton Jul 13 '19 at 4:22
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It is certainly possible to use buried seismic sensors to detect footsteps, but this is typically done using a specially designed seismic sensor cable.

So, does your definition of "accelerometer" include one that is in the form of a cable? If so then the answer to your question is yes. Whether this can be done using some other accelerometer would depend a great deal on which specific accelerometer you had in mind, how you planned to install it, and how you processed the signals from it.

You should know that avoiding false alarms from nearby vehicle traffic, thunder, and high winds is a non-trivial problem.

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    \$\begingroup\$ Relatively inexpensive earthquake sensors are available from raspberryshake.org \$\endgroup\$ – Warren Jul 12 '19 at 20:02
  • \$\begingroup\$ @Warren I'm not clear how this is relevant...nobody is trying to detect earthquakes. \$\endgroup\$ – Elliot Alderson Jul 12 '19 at 22:15
  • \$\begingroup\$ So what? The difference between a distant earthquake and nearby footprints may be more in what the software looks for than in the sensor needed. \$\endgroup\$ – Chris Stratton Jul 13 '19 at 4:23
  • \$\begingroup\$ @ChrisStratton Then Warren could have clarified their comment by saying just what you said. However, people have been doing this for decades; it's not an area where we don't know what works and what doesn't work. \$\endgroup\$ – Elliot Alderson Jul 13 '19 at 11:48

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