ANNOTATED VOLCANO: A VOLCANO'S SHAPE CAN TELL YOU HOW IT WILL ERUPT
YOU GET A double feature for the latest Annotated Volcano. Why two volcanoes? I wanted to explain the difference between two different shapes of volcanoes: the archetype stratovolcano and the massive shield volcano. Why would two volcanoes take such different forms? It boils down to the flavor and form of the stuff that comes out the top.
StratovolcanoMexico's Popocatépetl is an example of what volcanologists call a stratovolcano*, with a well-formed conical shape and a crater/vent at the top of the volcano. You can see that shape in the profile shot of the volcano (taken from the Earth's surface; below) with steep slopes. The average slope heading up the sides of the volcano are ~25 percent with a maximum of 63 percent in the steepest bits. From the "base" level of ~3500 meters (11,400 feet) to the summit you gain 1635 meters (~5,300 feet). All in all, hiking this volcano would definitely be a slog, especially as you approach the summit and the slopes get even steeper. You can also notice a nearly circular shape to the volcano (above), with paths of debris heading in all directions from the summit crater.
