If you live in an earthquake prone area, you can divine its epicenter using a dowsing pendulum. Hang the pendulum from a stable source. Next put under it a map of your region (or even the world). Be sure the map is aligned with true north.
Now observe, when an earthquake happens the pendulum will swing in the direction of the quake on the map.
If you are unable to constantly watch and wait, perhaps some mechanism can be devised to record which way the pendulum swings first.