The chain of earthquakes that shook the planet this week was violent and tragic, but can be explained A string of powerful earthquakes struck different parts of the world on Wednesday, prompting speculation over whether the events could be connected. While seismologists say they were not, the unusual cluster has raised questions about how earthquakes are linked, why some occur in pairs, and what terms such as “seismic doublet” and “earthquake swarm” actually mean. What happened? The week’s most