Scientists find regions of the earth’s core may be melting

May 21, 2011 – The inner core of the Earth may be melting, scientists now find. This melting could actually be linked to activity at the Earth’s surface, the researchers said, and added that the discovery could help explain how the core generates the planet’s magnetic field. The Earth’s inner core is a ball of solid iron about 1,500 miles wide, about the same size as the moon. This ball is surrounded by an outer core made up mostly of liquid iron- nickel alloy, a highly viscous mantle layer and, topping it off, a solid crust that forms the surface of the planet. As the Earth cools from the inside out, the molten outer core is slowly freezing. This is leading the solid inner core to grow at a rate of about 1 millimeter per year. However, scientists now find that the inner core might be melting at the same time. “The standard view has been that the inner core is freezing all over and growing out progressively, but it appears that there are regions where the core is actually melting,” said researcher Sebastian Rost, a seismologist at the University of Leeds in England. The roiling of material in the core, coupled with the spinning of the Earth, is what generates the planet’s magnetic field. For instance, when it comes to large regions under Africa and the Pacific where the lowermost mantle is hotter than average, the outer core below those areas can become hot enough to start melting the inner core. These findings suggest “that the whole dynamics of the Earth’s core are in some way linked to plate tectonics, which isn’t at all obvious from surface observations,” Mound said. To see if the core really is melting, “we would need larger arrays of seismometers spread more evenly around the world, particularly in the oceans, which is a technological hurdle,” Mound said. In addition, “we need to develop lab equipment that can explore the pressure and temperature conditions of the inner core — we are just on the edge of being able to do that reliably.” Mound, Rost and their colleagues David Gubbins and Binod Sreenivasan detail their findings in the May 19 issue of the journal Nature. –MSNBC