5.6-magnitude California tremor, 7.2-magnitude temblor in Japan and two quakes in Venezuela all struck within hours A 5.6-magnitude earthquake struck a rural part of northern California on Wednesday. Hours later, a 7.2-magnitude earthquake hit the northern coast of Japan and two powerful earthquakes rocked Venezuela in a devastating mass casualty event. The tremors happened in the span of eight hours, prompting online speculation over whether they were related.