Seafloor Eruptions Triggered by Tides, Ice Ages
Earth’s seafloor is born in fiery eruptions along volcanic mid-ocean ridges. According to a new study published this week in Geophysical Research Letters, those volcanoes are surprisingly sensitive to the tides—and they just might have something to do with ice ages as well.
Maya Tolstoy, a marine geophysicist at Columbia University’s Lamont-Doherty Earth Observatory, examined seismic records of ten seafloor eruptions. She found the eruptions tended to occur near “neap” tide, every two weeks, when the amount of seawater over the volcanoes is slightly lower than at other times. The reduced weight on the volcanoes apparently encourages small earthquakes, which can be associated with eruptions. (See “Pictures: Giant Undersea Volcano Revealed.”)
What’s more, all ten eruptions occurred during the first six months of the year, when Earth is moving farther away from the sun on its very slightly elliptical orbit. That’s when the sun’s tidal pull on Earth’s solid crust is diminishing in a way that also favors eruptions.
Those observations led Tolstoy to wonder whether seafloor volcanoes might also respond to the much slower but larger changes associated with ice ages.
http://news.nationalgeographic.com/news/2015/02/150207-volcano-eruption-ridge-milankovitch-ocean-earth-science/
