The researchers developed a new method to assess earthquake and tsunami hazards represented by the most distant part of offshore subduction zones and found that the hazard might have been systematically underestimated in some areas, meaning that tsunami risk assessments should be redone given the new results. The findings have important implications for the mitigation of risk in affected areas worldwide, including Southeast Asia and the Pacific Rim, in the event of future earthquakes and tsunamis. Megathrust earthquakes are among the most powerful earthquakes experienced worldwide and occur in subduction zones, where two tectonic plates converge, and one slides under the other. The plates move toward each other continuously, but if the interface, or fault, between them is stuck, then a slip deficit builds up over time. Like a debt, this slip deficit has to be paid off eventually, and for tectonic plates, payday is earthquake day. When these earthquakes affect the shallowest part of the fault near the seafloor, they have the potential to shift the seafloor upward and create devastating tsunamis as well.