Human Descends to Epicenter of Japan's Devastating Megaquake for First Time

The Ryukyu, Izu-Ogasawara and Japan ultra-deep ocean trenches, and the epicenter of the Great East Japan Earthquake, have been explored by humans for the first time.

A team of researchers at Caladan Oceanic & EYOS Expeditions, as well as self-styled ocean explorer and former U.S. Navy Officer Victor Vescovo completed a two-month expedition with the Japanese marine science community, exploring the deep-sea trenches and earthquake site.

Deep ocean trenches are long, narrow depressions on the seafloor, reaching deeper into the crust than any other point on Earth. They are formed by subduction, which is where two tectonic plates meet and one is pushed beneath the other. Vescovo has now descended into 17 of the world's 26 deep ocean trenches. The Ryukyu, Izu-Ogasawara and Japan trenches are each around 30,000 feet deep.

Earthquake epicenters are also usually positioned at points where tectonic plates meet, as the shifting of the plates against each other results in the release of seismic waves that cause earthquakes.

In this case, Vescovo and the team investigated the epicenter of the Great East Japan Earthquake, which occurred in 2011 and was the most powerful earthquake ever recorded in Japan, with a magnitude of 9.0 to 9.1. The resultant tsunami caused by the undersea quake hit the Fukushima Daiichi nuclear power plant, leading to the meltdown of three of the plant's nuclear reactors.

The earthquake's epicenter is positioned 45 miles east of the Japanese coast, at the meeting point of three tectonic plates: the Pacific, North American and Philippine Sea plates. According to Vescovo, a "triple junction" of converging tectonic plates is very unique, with there being only two places in the world where that happens.

"The reason we visit earthquake sites is that we are looking to explain why trench animals are so different from the rest of the deep-sea," Vescovo told Newsweek. "A big difference between the trenches are the relatively wide-open abyssal plains is that the trenches are much more seismically active.

"Abyssal plain species are old, some greater than 100 years old and they likely spawn only every few decades. If these lived in trenches where large portions of the habitat were being destroyed by seismic events, the population is just too old and inefficient to bounce back."

Despite being incredibly deep, the abyssal plain is actually teeming with life. Scientists have found 2,000 species of bacteria, 250 species of protozoans, and 500 species of invertebrates living at these depths.

"We have acquired a lot of evidence to show that trench species are generally much younger—for example, snailfish commonly present in the trenches are usually 10-15 years old and therefore have adapted to bounce back more quickly after a severe disruption," Vescovo said.

"Wherever we look, depth has little to do with how the species live and reproduce. Other environmental factors, such as the level of seismic activity are often more important. This is also why we are going back to the New Hebrides Trench as a very recent dive there indicated that it had experienced a much more recent seismic event and so catching these things at various time intervals will tell us more about the level of disruption and recovery."

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The deepest ocean trench in the world is the Mariana Trench, which reaches down to around 35,830 feet below sea level at Challenger Deep, its lowest point. It has been explored by several manned and unmanned craft, most recently on May 8, 2020, where a Russian submarine descended 32,900 feet. These descents take a long time, taking about three and a half hours to descend and another three and a half to come back up.

"Spending two to three hours on the bottom, one can end up spending over ten hours in the submersible on a typical research dive," Vescovo said.

"It is not dangerous at all. The submersible has been specially designed to make it as absolutely safe as possible and is the first ultra-deep ocean submersible built and certified to commercial standards. That means it has gone through testing and approvals similar to what a commercial airliner would have. There has never been a life-threatening situation in the last four years of continuous operation of the sub. It is extremely safe."