It was aboard the "Limiting Factor" submarine that the director of the Millennium Oceanographic Institute of the University of Concepcion dived in January into the Atacama Trench, a huge hole in the Pacific Ocean that extends over 5,900 km from Ecuador to southern Chile.

The historic "Atacama Hadal" expedition, with American explorer Victor Vescovo and Millennium deputy director Ruben Escribano, lasted 12 days off the coast of northern Chile.

“At a depth of 100 meters, there is no light, which adds to the silence of the depth,” says Mr. Ulloa.

They "turned on the powerful LED lights installed outside the submarine's capsule" to see what no human eye had ever been able to see before.

"We came across geological structures and we saw there a type of holothurians, or sea cucumbers, translucent and gelatinous that we had never listed", details the scientist.

"Furthermore, we discovered bacterial communities that even had filaments that we didn't know existed in the Atacama Trench and that would feed on chemical and inorganic compounds. This opens up many questions: which compounds are it? what type of bacteria is it?

To these questions he says he has "no idea" of an answer: "we will have to go back".

The expedition also found species of amphipods, scavenger crustaceans discovered during an unmanned expedition in 2018, segmented worms and translucent fish.

Photo provided by Caladan Oceanic - IMO of the "Limiting Factor" submarine used for the record exploratory mission at 8,000 m depth, on January 20, 2022 off Antofagasta, Chile Matias PIZARRO CALADAN OCEANIC - IMO/AFP

"The large population of these organisms found runs counter to what we knew: as the depth increases, the abundance and diversity of organisms decreases," he added.

Seismic sensors

The Atacama Trench is located where the Nazca Plate and the South American Plate, two of the oceanic plates that are part of the Pacific Ring of Fire, collide.

"We will place three sensors on the South American plate and two on the Nazca plate to see how the ocean floor is deforming, (today) these types of sensors only exist on land", specifies Osvaldo Ulloa.

Photo provided by Caladan Oceanic - IMO of Chilean scientist Osvaldo Ulloa (d) and American explorer Victor Vescovo after completing the record exploratory mission at 8,000 m depth, on January 20, 2022 off Antofagasta, Chile Matias PIZARRO CALADAN OCEANIC - IMO/AFP

"The sensors will allow us to know in which area there was no earthquake and where the energy is accumulating, which could help predict the location of the next earthquake."

"It's an extremely ambitious project," he says, of what he describes as "the greatest experiment ever carried out in underwater geology in Chile."

According to him, "installing more sensors and using this region to study all the processes associated with the collision of these two plates is attracting a lot of interest from the international community".

The installation of the sensors should begin in the second half of the year.

© 2022 AFP