Earthquakes that jiggle Earth's middle layer may be more widespread than scientists thought.
A new map of these mysterious deep earthquakes shows that they occur all around the world and that they may have a variety of causes. That's interesting, said study senior author Simon Klemperer, a geophysicist at Stanford University, because mantle earthquakes were once thought to be impossible, or at least rare. These quakes originate below a border known as the Mohorovičić discontinuity, or "Moho" — the line between the brittle crust and the hotter, gooier mantle.
