Explaining new jolts rattling earthquake-ravaged Italy

A wave of earthquakes has rocked central Italy in recent months, shattering medieval towns and destroying ancient homes, churches and landmarks. The latest—a magnitude 6.6—over the weekend struck a cluster of historic mountain towns, the most powerful temblor to hit Italy in more than three decades. The new shaking comes as the region reeled from a deadly magnitude 6.2 quake in August that killed 300 people and a pair of strong quakes last week.