In September, over 50 people died during a volcanic eruption in Japan. Iceland continues to experience its largest continuous volcanic eruption in centuries. On this week's Please Explain, we are talking about volcanoes: how are they formed, how dangerous are they, and how scientists monitor them. We will be joined by Mika McKinnon, a geophysicist and journalist with the science publication i09, and David Schneider a USGS Research Geophysicist at the Alaska Volcano Observatory.