Volcano Watch: What is a volcano?

  • USGS photo This photo looks west towards the upper East Rift Zone of Kiauea. The fume-filled crater at Pu‘u ‘O‘o is in the foreground, and the vent for the June 27 lava flow is just out of view of the lower right corner of the photo. Mauna Loa is visible in the upper right.

What makes a volcano a volcano? This was the topic of a “Volcano Watch” article about 20 years ago. Recent questions from visitors suggest this remains a topic of great interest and deserves revisiting.