Scientists drill 8,023-metre deep hole off Japan to study history of earthquakes in the region

Japan is hit by an average of 1,500 earthquakes each year. Now to study the history of the earthquakes in the region, scientists drilled the deepest hole in the seabed of the Pacific Ocean near the Japan Trench on May 14.

The crew of Expedition 386 drilled 8,023 metres deep into the Pacific Ocean, breaking the record for the deepest coring site in the 50 years history of scientific ocean drilling.

Expedition 386 is a paleoseismology mission under the International Ocean Discovery Program. Paleoseismology is a field of study that investigates geologic sentiments and rocks for the signs of ancient earthquakes.

Chief scientists Michael Strasser said that a 40 metre long Giant Piston Corer was lowered into the ocean at the speed of 1.1 metres per second. In 2 hours and 40 minutes, the drill reached just above the seafloor and the deepest water site of the expedition, at a depth of 8 kilometres. The corer went 844 metres deep penetrating the seafloor.

From the site, termed as Site M0081 by the scientists, the team extracted a total of 37 metres of sediment. The sample, collected at the record depth, set another record for the deepest sub-sea level sample found in scientific drilling. The previous record was held by a sub-sea level sample collected at a depth of 6889 metres during a drill in the same Japan Trench in 2012.

However, the record for the deepest coring site was previously held by a 1978 drilling in Mariana Trench which went as deep as 7034 metres recovering about 20-metre long samples.

The study is expected to help scientists in understanding the environmental changes that happened over time and how they affected the proneness of Japan to earthquakes.

The mission will also help the scientists understand marine processes and their effects, solid Earth cycles and dynamics and the deep biosphere.