Earthquakes not only shake the surface of the earth, they are also a crucial key to unlocking many of the inner earth’s most hidden secrets. I’m Jim Metzner and this is the Pulse of the Planet, presented by DuPont.
ambience: Earthquake sound
We’re listening to the speeded up recordings of a South American earthquake.
Mike Brown is the chair of the geophysics program at the University of Washington in Seattle.
“Earthquakes can generate waves that can propagate down through the mantle, through the liquid outer core, then through the inner core and then back up to the surface again. One of the exciting discoveries seems to be that this inner core does not rotate at the same speed as the rest of the Earth. ”
What scientists discovered is that the earth’s inner core is rotating at a slightly faster speed than the surface of the earth. And how did we learn this?
“Well by going back over thirty years worth of seismic data it was recently discovered that the time it takes for seismic waves to travel from a remote location in the south Atlantic Ocean down through the core and up to Alaska has actually changed. The time has changed and the only place that that change could occur is within the inner core.”
Scientists have taken advantage of the fact that a powerful earthquake’s vibrations permeate our entire planet. Careful monitoring of an earthquake’s soundwaves have given scientists a picture in sound (a giant sonar map) of the inner earth – and that picture reveals a rotating core. Pulse of the Planet is presented by DuPont, bringing you the miracles of science, with additional support provided by the National Science Foundation. I’m Jim Metzner.