Biggest underwater eruption makes new volcano bigger than Empire State Building

The largest ever-recorded underwater eruption created a volcano on the seabed from a height of 2,690 feet.

The volcano, twice as tall as the Empire State Building, was not present off the east coast of the island of Mayotte in the Indian Ocean before an earthquake rocked the island in 2018 .

The underwater seismic event generated more than 11,000 detectable earthquakes in what the authors of a Nature documenting document describes it as a “major magmatic event”. The event, which caused the deformation of the seabed, was so significant that it was recorded beyond the Indian Ocean and around the world.

“Volcanic eruptions shape the surface of the Earth and open a window into deep Earth processes,” the authors said. “This is the largest active underwater eruption ever documented.”

The authors added that the new volcanic edifice sits at the tip of a 31-mile-long ridge created by other recent lava flows. This new structure extends between the faults of East Africa and Madagascar and could help researchers better understand the processes behind tectonic activity on Earth.

The earthquakes began on May 10, 2018 and were followed by a magnitude 5.8 earthquake five days later. Scientists investigating the seismic event discovered that it was an underwater volcanic eruption on a scale researchers had never recorded before.

A team of scientists led by the geophysicist from the University of Paris Nathalie Feuillet, also main author of the Nature paper, placed a range of technological devices, including seismometers on the ocean floor in the region, to determine the origin of seismic activity. They also surveyed the area with an echo sounder which used radar signals to reveal the 2,690-foot-high volcanic structure.

Between late February and early May 2019, the team discovered around 17,000 seismic events at a depth between 12 and 31 miles below the ocean floor, more than most earthquakes. By searching at low frequency, they also found 84 other events.

The data collected by the team allowed them to reconstruct the events that led to the creation of the new volcano. They believe tectonic processes may have damaged the outer solid part of the Earth, including the crust and mantle known as the lithosphere.

This caused the magma reservoirs under this layer to rise to the upper layers through dikes and also triggered the reactivation of faults that already existed in the mantle. They caused the earthquakes and led to the magma flowing to the seabed where it erupted to cause the production of a cubic mile of lava and the new volcano.

The authors said the eruption was not only the largest ever recorded on the seabed, but that it was six times smaller than what is considered the largest volcanic eruption since records began, l eruption of Laki in Iceland from 1783-1784.

“The volumes and flows of lava emitted during the Mayotte magmatic event are comparable to those observed during eruptions at the largest hot spots on Earth,” said the authors.

As of May 2021, when the article was written, the authors claim that the earthquakes were still continuing and the region’s seabed continued to deform.

Besides the creation of this new volcano, the event marks the first time that earthquakes have been measured off the coast of the French island since 1972, and the most recent volcanic activity in the region dates back to there between 4,000 and 6,000 years old.

“Future scenarios could include a new caldera collapse, undersea eruptions on the upper slope, or onshore eruptions,” the authors concluded. “The large lava flows and cones on the top of the slope and on the coast of Mayotte indicate that this has happened in the past.”