Aster acknowledged that the rarity of large earthquakes means that questions about possible connections between them are difficult to answer. "We see magnitude-7 earthquakes only 15 or so times a year and magnitude-9 earthquakes only a few times a century," he said.
Michael said that until researchers know more about why the rate of large earthquakes varies over time "we shouldn't be worrying less, but there's no need for panic either."
The recent spate of giant earthquakes may not signal more to come, but Aster said that "it's undeniable that we're becoming more and more vulnerable to the effects of earthquakes in general."
Aster added that many rapidly growing cities around the world aren't prepared for a large quake, while at the same time coastal communities are expanding into tsunami-prone areas. "We just have more people in precarious places," he said.