Why do clocks stop during an earthquake?

Earthquakes stop SOME clocks. Any clock which is smashed will, of course, stop working. Fortunately not all clocks are smashed. read more

Most clocks do not stop during an earthquake. Earthquakes that are strong enough to trigger a power outage will stop electric clocks. The jolt of a strong quake could stop the pendulum of a grandfather clock in it’s tracks. read more

if you shake a grandfather clock like a beast then the gears inside would stop working. electronic clocks on your wrist or wall wouldn't. it IS pretty violent in earthquakes. read more

Once the swing falls below the point where it can trigger the escapement the clock will stop. You can simulate these effects with a simple yoyo or a weight on a string. Let it hang and set it swinging smoothly on a nice pendulum arc, then after a couple of swings, begin to rapidly move your hand side to side in the same line as the pendulum is swinging. read more