What is causing the violent volcanic eruptions in Indonesia?

Repeated volcanic eruptions on a remote island in the Indonesian archipelago have prompted authorities to issue a tsunami alert and order more than 11,000 people to leave the area. Indonesia sits along the "Ring of Fire" and has 120 active volcanoes. Host Carolyn Beeler speaks to volcanologist Tracy Gregg at the University at Buffalo about what she's noticing about the lava flows in this particular volcano.