Tokyo: A Japanese research vessel carrying the world s largest deep-sea drill has completed its first expedition after collecting data it hopes will help discover more about earthquakes, officials said today.

The 210-meter ship Chikyu the Japanese word for "Earth"  was on a mission to clarify the causes of earthquakes and uncover the secrets of climate change. Chikyu yesterday completed its first 56-day assignment in the Nankai Trough, a Pacific Ocean zone between two major tectonic plates that has produced powerful, destructive earthquakes off southwest Japan over the past 1,500 years, according to the Japan Agency for Marine-Earth Science and Technology, which developed the USD 513 million vessel.

Geologists had planned to drill deep into the ocean floor to the boundary between the oceanic and continental plates for the first time into what's known as a seismogenic zone the flash point for quakes. The Chikyu successfully drilled 12 holes as low as 1,400 meters at six sites below the sea floor and obtained high quality images and data, the agency said in a statement.
When the drill went deeper than 1,000 meters below the sea floor, scientists found a structure just above a seismogenic zone that faced both pulling and pushing force key data indicating how underground stress accumulates.

"We have found out some of the sites where earthquakes are in preparatory process," project chief Masataka Kinoshita told public broadcaster NHK. "We plan to collect more data for further analysis."

Source : PTI