The charge amplifier on one of the seismometers has been changed to respond to 1.5 Hz and below. It was a simple resistor change, of the rightmost resistor on the handwritten schematic down below. The resistor was 1000 Ohms and now it is 10,000 Ohms.

Up until now the amplifier has been using a 15 Hz low pass filter. It's going to take a couple of days to collect enough data to get the device's sensors calibrated. The plan is to run the 1.5 Hz device and a 15 Hz device side by side until "something seismic" happens, then compare and contrast the results.