Giant 'Lava Lamp' Inside Earth May Cause Magnetic Poles to Flip
By Paula Koelemeijer, University of Oxford | May 15, 2017 03:49pm ET
- click for image -
https://img.purch.com/h/1400/aHR0cDovL3d3dy5saXZlc2NpZW5jZS5jb20vaW1hZ2VzL2kvMDAwLzA5Mi8yODAvb3JpZ2luYWwvZWFydGgtY29yZS1sYXllcnMuanBn
If you could travel back in time 41,000 years to the last ice age, your compass would point south instead of north. That's because for a period of a few hundred years, the Earth's magnetic field was reversed. These reversals have happpened repeatedly over the planet's history, sometimes lasting hundreds of thousands of years. We know this from the way it affects the formation of magnetic minerals, that we can now study on the Earth's surface.
Several ideas exist to explain why magnetic field reversals happen. One of these just became more plausible. My colleagues and I discovered that regions on top of the Earth's core could behave like giant lava lamps, with blobs of rock periodically rising and falling deep inside our planet. This could affect its magnetic field and cause it to flip. The way we made this discovery was by studying signals from some of the world's most destructive earthquakes.
Around 3,000km below our feet – 270 times further down than the deepest part of the ocean – is the start of the Earth's core, a liquid sphere of mostly molten iron and nickel. At this boundary between the core and the rocky mantle above, the temperature is almost 4,000 degrees Celsius, similar to that on the surface of a star, with a pressure more than 1.3m times that at the Earth's surface.
More:
http://www.livescience.com/59113-giant-lava-lamp-hidden-inside-earth.html?utm_source=notification
