Deep drilling record

Scientists with the International Ocean Discovery Program set a record on May 14. Floating over the Japan Trench, the crew of the Research Vessel Kaimei lowered machinery 26,322 feet—or nearly five miles—to take the deepest-ever ocean floor core sample for scientific research.

Formed by the subduction of the Pacific Plate under the Okhotsk Plate, the Japan Trench is one of the world’s hot spots for seismic activity. It was the source of the 9.0-magnitude earthquake in 2011 that shook Japan and caused the meltdown at the Fukushima Daiichi Nuclear Power Plant. Scientists with IODP’s expedition 386 chose the site less than 100 miles from the coast of Japan because of its proximity to the epicenter of the destructive 2011 quake.

Taking samples of the ocean floor at such extreme depths could help seismologists understand the effects of earthquakes from a vantage point inaccessible to normal instruments. The deeper the core sample, the more earthquake history scientists can study. According to the U.S. Science Support Program, the Kaimei crew’s 120-foot core sample could reach deep into the history of earthquakes in the Pacific Rim, potentially expanding the historical record by 10 to 100 times.

Once in place over one of the deepest parts of the trench, the crew of the Kaimei lowered a 131-foot giant piston corer on a tether toward the ocean floor. It took two hours and 40 minutes for the corer to reach the seabed and almost another three hours to pull the sample back to the ship. The depth of the hole the crew dug breaks the record set during a 1978 expedition over the Marianas Trench.