Much of the volcanic activity on Earth takes place at depths of several kilometers under the ocean.
Our understanding of Earth’s ocean floor is less than that of Mars. Here, scientists believe that the unusual physical and chemical conditions associated with hydrothermal systems on the seafloor may have created the right environment for the origin of life on Earth. Mysterious Megaplume Scientists discovered large areas of thermal fluid in the ocean above volcanic ridges. These large and powerful hot waters, rich in chemicals, rising from the ocean floor are called megaplume. Their size is really huge, with a volume that can exceed 100 km3, equivalent to 40 million Olympic swimming pools. Although they appear to be related to subterranean mountain eruptions, their origin remains a mystery. In their study, the scientists used a mathematical model to explain the dispersion of volcanic ash across the ocean. Thanks to detailed mapping of a volcanic ash deposit in the Northeast Pacific, scientists know that this ash can spread up to several kilometers from an eruption. This cannot be easily explained by tides or other ocean currents. Instead, the results suggest that these water columns are very energetic. The energy required to drive the flow and carry the ash is surprisingly large, about 1 terawatt (nearly half of the energy needs of the entire United States at a time). The scientists calculated that this would create water columns of similar size as said. They have since produced strong evidence that megaplumes are associated with active seafloor eruptions and that they form very quickly, possibly within hours. So what is the source of heat and chemicals to make this megaplume? The most obvious candidate is of course newly erupting molten lava. At first glance, the scientists’ results seem to support this hypothesis. Accordingly, the formation of megaplume occurs simultaneously with the eruption of lava and volcanic ash. However, when the scientists calculated the amount of lava needed for the megaplume, it was unrealistically high, about 10 times larger than most underground lava flows. The scientists’ best guess is that although the occurrence of megaplumes is linked to undersea eruptions, they are mainly derived from depleted hydrothermal reservoirs present in the ocean. . As the lava directed upward to create undersea eruptions, it may have pushed this liquid hotter than 300 degrees Celsius along.
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