Rotating Earth (IMAGE) University of Maryland Caption Earthquakes, seen as yellow stars here, send sound waves through the Earth. Seismograms, seen as blue triangles here, record the echoes as those waves travel along the core-mantle boundary, diffracting and bending around dense rock structures. New research from University of Maryland provides the first broad view of these structures, revealing them to be much more widespread than previously known. Credit Doyeon Kim/University of Maryland Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.