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Drilling ship Chikyu returns deepest seabed core samples yet

Posted on behalf of Nicky Guttridge.

Japanese deep-sea drilling vessel Chikyu has bored into the sea bed and recovered rocks from more than 2.11 kilometres beneath the sea floor, the Japan Agency for Marine-Earth Science and Technology announced on 6 September. Although oil wells frequently reach deeper, this is the first scientific expedition to retrieve core samples from such depths.

This tops the previous record, set by US research ship JOIDES Resolution at the Costa Rica Rift, by mere centimetres. The ship will continue to drill deeper into the sea bed during the remaining 3 weeks of the expedition.

Chikyu is part of the Integrated Ocean Drilling Program (IODP), an international programme of research that uses ship-mounted equipment to drill down into the sea. It aims to access and sample regions beyond Earth’s crust, such as the deep seisomogenic and biosphere zones. Chikyu is drilling off the coast of Japan in the fault zone responsible for the 2011 Tohoku earthquake, collecting samples in order to study the region’s geological history. By examining deeply buried formations of rock and coal, the Chikyu team also hope to learn more about deep-sea hydrocarbons and microbial activity.

Chikyu first broke records in April of this year for deep-sea drilling when it reached 7.7 kilometres below the ocean surface. This represents a hole in the crust 860 metres deep, as the measurement includes the 6.9 kilometres of water sitting atop the sea floor. This exceeded the previous record depth of 7.05 kilometres, set in the Mariana Trench in 1978 by US vessel Glomar Challenger.

The expedition hit a setback when the Tohoku fault sprang to life in March 2011, causing a magnitude-9.0 earthquake and subsequent tsunami. Chikyu was docked on Japanese waters during the tsunami — filled with schoolchildren on a field trip. Nobody was hurt, but the ship scraped the sea floor and suffered damage that required several months to fix.

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    Paul Gabrielsen said:

    The expedition hit a setback when the Tohoku fault sprang to life in March 2011, causing a magnitude-9.0 earthquake and subsequent tsunami.

    The expedition did not commence until after the earthquake, and was in response to the earthquake. https://www.iodp.org/return-to-the-japan-trench

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