A group of international researchers including Japanese professors says it found a huge cliff in deep waters near the epicenter of the 2011 Great East Japan Earthquake.

The group consists of scientists from Japanese and overseas universities and research institutes, including Niigata University, and the Tokyo University of Marine Science and Technology.

In September last year, the group used the manned US submersible Limiting Factor to explore the seabed about 7,500 meters deep in the Japan Trench, off Miyagi Prefecture.

The survey discovered that a nearly vertical cliff with a height of about 26 meters was created near the epicenter. The researchers also found that the surrounding area was dotted with angular mud blocks, which are said to be formed when mud accumulating on the seabed suddenly collapses.

The group says such a topographic feature was not confirmed when a different research team conducted a sonar survey in the same area before the 2011 earthquake.

The group put forward the idea that the powerful earthquake could have caused a fault to slip deep under the seabed and move up about 60 meters, with the upper part believed to have emerged as a cliff.

The researchers say this is the first time that they have filmed the fault appearing on the seabed after the earthquake.

Ueda Hayato, associate professor of Niigata University, went down into the deep ocean inside the submersible.

Ueda said he was able to confirm that something extraordinary occurred on the seabed when the 2011 earthquake struck.

He added that understanding details of seabed changes triggered by earthquakes can create tsunami simulations more accurately.