60,000-year-old giant submarine landslide identified

An enormous submarine landslide that disintegrated 60,000 years ago produced the longest flow of sand and mud yet documented on Earth.

Washington, Nov.22 : An enormous submarine landslide that disintegrated 60,000 years ago produced the longest flow of sand and mud yet documented on Earth.

The massive submarine flow travelled 1,500 kilometres - the distance from London to Rome - before depositing its load.

According to Dr. Peter Talling of the University of Bristol and colleagues from the National Oceanography Centre in Southampton and several other institutions, this mass was ten times that transported to the ocean every year by all of the Earth's rivers.

"The flow was sometimes over 150 km wide, spread across the open sea floor," Dr. Talling says in his report that has been published in the journal Nature.

Perhaps the most remarkable thing about this giant submarine flow is that it travelled hundreds of kilometres without depositing any sediment on the vast expanse of sea floor that it passed over.

Sediment deposition was finally triggered by a remarkably small but abrupt decrease in sea-floor gradient (from 0.05 degree to 0.01 degree).

Understanding the cause and evolution of these infrequent undersea flows helps to assess any potential hazards posed to such structures.

This work suggests that a more accurate record of these flows is found by coring in the low-gradient basin plains, which may be hundreds of kilometres from the installations.

ANI