Japan’s deadliest fault line shifts, frustrating megaquake forecasts

A Japanese study has found that the locked zone in the Nankai Trough is not permanent but changes over time, further complicating the task of predicting megaquakes along the fault line.
A locked zone is where tectonic plates merge, allowing stress to build up until it is released in an earthquake. In the case of the 900km (560-mile) long Nankai Trough off Japan’s Pacific coast, it is where the Philippine plate meets the Eurasian plate.
The Philippine plate is slipping under the Eurasian plate at...