Pull-apart Mountain on Io (IMAGE) Washington University in St. Louis Caption This is Hi'iaka Montes. The dark area at center of this 'pull apart' mountain is a wide volcanic crater called a patera. Credit NASA/JPL 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.