Earthquakes stop SOME clocks. Any clock which is smashed will, of course, stop working. Fortunately not all clocks are smashed. Your wristwatch will likely NOT stop during an earthquake, neither will that battery-powered WWV clock on your kitchen wall stop. 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