Up and Running with New Sensor

A project log for Seismometer

An inexpensive Lacoste pendulum seismometer

Bud BennettBud Bennett 02/23/2019 at 05:360 Comments

A few days ago I replaced the homemade displacement sensor with a shiny new set of PCBs for the rotor and stator plates. It's been pretty quiet out there in the world lately, but today there was a rather large event in Ecuador -- magnitude 7.5 near the border with Peru. The quake was captured by the seismometer.

Unfortunately, there was another spurious event recorded at 18:48UTC. This kind of stuff happens when you disturb the seismometer (or it was an insect crawling around on the boom) -- and it takes a few days for the mechanism to settle out. In any case it appears that the new sensor is working well.

This event is about 6400km from my place in Colorado. Previously, I estimated that 1 count of the cap2dig converter was equivalent to about 0.3nm of displacement. This quake caused the floor of my garage to move about 3µm.

Here's a stripline plot of the same event (added text is mine).

This is what the Z-axis seismometer in Albuquerque, NM picked up:

I might need to adjust the filter parameters a bit to pick up the lower frequency energy...but this is what the Z-axis seismometer picked up in Pinedale, WY:

and it's pretty close to what I got.