My 1" geophone is telling me where the freight train energy is. Comparing a confirmed freight train with my quiet Salem baseline, I found strong sub-20 Hz ground vibration: around 10.7-10.9 Hz the maximum increased ~33 dB, and at 6.07 Hz the median increased ~21 dB. Next stop: field measurements far and near hyperscale data centers. https://salemdata.net/johnpress/?p=1288 #Geophone #Seismology #GroundVibration #FreightTrain #CitizenScience #DIYScience #DataCenters #SalemOR