robtillaart:
idea:
you could place a horizontal line laser near the pendulum so a shadow is cast on the wall with sensitive detectors. If the laser is placed near the pendulum there is an angular magnification (I don't know how to call it otherwise). A slight movement of the pendulum gives a larger displacement on the wall. It is easy if the pendulum is a cilinder to detect X and Y movements. Then one can calculate in which direction the cilinder moves first, and this might be indicative for the direction of the epicentre.idea ?
I can imagine a sphere floating in a magnetic field as pendulum. Then 3 dimensions might be possible?
Rob:
I think that idea might go to he11 in a hand basket if there is too much motion in three dimensions. You can't even be sure that the wall be there to hold the sensors in a large quake... ]
Imaginative though...