Underwater volcano likely erupting in Pacific Ocean near Mariana Trench since mid-October, experts say

Scientists believe there is likely a volcanic eruption happening somewhere deep in the Pacific Ocean near the US Northern Mariana Islands, but because of its inaccessible location, they are unable to say for sure whether such an event is happening.

The Northern Mariana Islands, also called Northern Marianas, is officially referred to as the Commonwealth of the Northern Mariana Islands and is a self-governing commonwealth in association with the US.

The region is made up of 22 islands and islets in the western Pacific Ocean and is part of a chain of volcanic mountain peaks and uplifted coral reefs, which included the politically separate island of Guam, located about 207km southwest.

On Monday, the US Geological Survey announced in a statement that evidence pointed to a seismic event having begun occurring at Ahyi Seamount, located about 6,115km west of Honolulu, sometime in mid-October.

But, they admitted, they could not confirm whether that event was a series of shallow earthquakes or if it was simply material exploded from the crater, Matt Haney, a USGS research geophysicist, confirmed during an interview with The Associated Press.

“There’s nothing right now that suggests that this eruption will intensify and become a large eruption,” Mr Haney noted, but warned that seafarers and boaters should avoid the affected area for the time being.

Satellite data seemed to suggest that volcanic material was indeed eking from the volcano, as images viewed by the USGS team showed discoloration in the waters near the suspected site.

Activity was first picked up in October, when hydroacoustic sensors monitoring a region more than 2,250km away – at a spot called Wake Island – were alerted.

Hydroacoustic monitoring, often used to detect the depth of a water body, can also be deployed to pick up the presence or absence, abundance, distribution, size, and behaviour of underwater plants, animals, or even volcanoes.

Through the assistance of a team of experts at the Laboratoire de Geophysique in Tahiti and data from seismic stations in Guam and Japan, scientists were able to analyse the signals to determine the source, which they determined to likely be the aforementioned Ahyi Seamount, the USGS said in a statement.

While activity has been waning in recent days, the agency acknowledged that they don’t currently have any sensors set up in the immediate area of the large conical submarine volcano known as Ahyi Seamount.

“There are no local monitoring stations near Ahyi Seamount, which limits our ability to detect and characterize volcanic unrest there,” the agency said. “We will continue to monitor available remote hydrophonic, seismic, and satellite data closely.”

The seamount, with a highest point of 79 meters below the surface of the ocean, is located just 18km southeast of the island of Farallon de Pajaros, also known as Uracas.