Scientists have uncovered evidence of an unexpected process that may allow earthquake faults to slip enormous distances.

Rocks along Japan’s Boso Peninsula have preserved evidence of an extraordinary process that may occur during powerful earthquakes. Researchers discovered ancient fault structures suggesting that clay trapped between moving rock surfaces became nearly as fluid as water, potentially allowing the fault to slip enormous distances with little resistance.

The findings, from a research team led by Professor Tetsuro Hirono of Osaka Metropolitan University, could help explain how some earthquakes produce the massive seafloor movements capable of triggering devastating tsunamis.