Scientists Drilled the World’s Deepest Ocean Hole Off Japan’s Coast

Scientists have drilled the deepest-ever ocean hole off the coast of Japan, breaking the record from the Mariana Trench in 1978 as they try to gain new insights into the region’s earthquake history.

An international team aboard a research ship accomplished the feat on May 14 in the Pacific Ocean more than 26,322 feet, or nearly 5 miles, below sea level.

Located near the epicenter of the 2011 Tōhoku earthquake, which caused a tsunami and subsequently the Fukushima Daiichi nuclear disaster, the hole is part of a marine mission that returned debris from ancient earthquakes.

“The deeper you go into the ocean, the older the samples get,” said Nobuhisa Eguchi, the director of the operations department at the Japan Agency for Marine-Earth Science and Technology, which collaborated with the International Ocean Discovery Program to carry out the drilling.

“During earthquakes, bits of the earth fall into the ocean and settle on flat seabed. And that continues to collect, which is why we aimed to go to those depths,” Eguchi told VICE World News. 

The hole was drilled using a 40-foot-long piston corer, a heavy tube used to extract sediment from the seabed.

In drilling the hole, scientists aboard the Japanese vessel Kaimei broke another record: obtaining the deepest sub-sea level sample. This region is known as the hadal zone and is the deepest in the ocean, with depths measuring 20,000 feet to 36,000 feet. 

With the nearly 124-foot-long sample of gathered sediment deposits, scientists aim to preserve details of much older, undocumented earthquakes. 

The research team focused on a location near the site of the 2011 Tōhoku disaster, where a 9.1 magnitude earthquake erupted a decade ago, causing extensive damage and killing more than 20,000 people.

The group hopes to further develop submarine paleoseismology, a discipline that seeks to study prehistoric earthquakes by collecting information from the geological record, such as magnitude and recurrence of earthquakes.

“Before humans even came to exist, the earth was experiencing earthquakes,” Eguchi said.

Through the mission, “we can learn how frequent and big they were. We’ve never had this knowledge in human history,” he said. 

Eguchi said that results of the expedition will most likely be released in autumn of this year.

Previously, the world’s deepest water drill record was held by the crew aboard the U.S. vessel RV Glomar Challenger in 1978, when scientists extracted sediment from the ocean floor in the Mariana Trench in the western Pacific at depths of 23,077 feet and 23,061 feet. 

On land, the deepest hole drilled into Earth’s surface is the Kola Superdeep Borehole, made in the 1970s by Soviet scientists near the Russian border with Norway. At 40,230 feet, it took 20 years to drill and reached about one-third of the way through the crust.

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