The March 11, 2011 earthquake and tsunami that hit Japan were generated on a fault that didn't rupture the usual way, according to researchers. The rupture initially shot westward, then slowed and began rupturing rapidly eastward. The "flip-flop" fault motion first shook Honshu violently, then deformed seafloor sediments on the fault plane with such force that they triggered the huge tsunami. What researchers don't know is whether comparable faults could behave in a similar fashion....