Submarine behemoths: Volcanoes
A study at the Earth Institute at Columbia University explains how the phenomenon of submarine eruptions follows surprisingly regular cycles: from two weeks to tens of thousands of years, and almost exclusively between January and July of each year. Possible relationships with the global climate.
There are more than 10 thousand, hidden under the water. Some are tall even more than 4000 meters. And spit columns of hot lava with the punctuality of a Swiss clock. Are the underwater volcanoes, gigantic gaping gorges fire deeper into the ocean – the bigger, the Tamu, in the eastern Pacific covers an area almost as big as Italy – which manufacture new earth crust at mid-ocean ridges and subduction zones, where the tectonic plates slide over each other submerging in the mantle to melt and, the next day, resurface again in the form of gas and lava. Geologists consider them fondly the gentle giants of the planet.
Recently formed pillow lava
Credit: Deborah Kelley / University of Washington.
A new study conducted by researchers from the Earth Institute at Columbia University, and just published in the columns of the Geophysical Research Letters describes how the phenomenon of submarine eruptions follows surprisingly regular cycles: every two weeks by a rarest emission phenomena and however repeating time every 100 thousand years. But there’s more: the underwater volcanoes prefer the first half of the calendar year and their eruptions are concentrated almost exclusively between the months of January and July.
To regulate the biological clock of these submarine behemoths there is the path made by the heavenly planet Earth in its orbit around the sun. It is a phenomenon that certainly contributes also to trigger natural climatic oscillations. According to scientists at Columbia University the amount of carbon dioxide emitted into the sea directly and indirectly in the Earth, it would be able to influence in a non-negligible global climate.
“We cannot continue to ignore the action carried out by underwater volcanoes, the role that is neither small nor insignificant as they used to think,” says Maya Tolstoy, marine geophysics of the Lamont-Doherty Earth Observatory of Columbia University, among signatories of the article published in Geophysical Research Letters.
The submarine volcanoes dot the ocean floor at the back as the seams on a baseball. There are 37 thousand kilometers of open wounds in the Earth’s mantle that annually produce a quantity of lava eight times greater than what we can see with our eyes, on the surface, erupted from volcanoes on Earth. Something like 88 million tons of CO2 each year, according to the calculations presented by the researchers.
It is widely believed among a number of geologists that the biological clock of underwater volcanoes is set on Milankovitch cycles – a constant change of the orbit followed by the Earth around its star with periodic changes in inclination and direction of the axis – makers of swing of hot and cold periods. The main of these cycles follow a period of 100 thousand years where our planet takes positions closer and further away than the sun. But the debate is open.
The real point is that the submarine eruptions are almost impossible to observe and monitor. That, however, has not prevented Tolstoy and his companions to follow closely ten submarines sites and use new and sophisticated seismic instruments to collect a wealth of data essential to produce new maps, high-resolution, showing the profile of the lava flows of today and yesterday.