Volcanic Unrest Objective Students learn how scientists determine how dangerous an active volcano might be. Directions Tell students that many mountains in countries like Japan are actually active volcanoes. Scientists in Japan study many aspects of their volcanoes, including lava viscosity. Viscosity is the internal friction of a liqud, or its ability to run fast or slow.
Water is a liquid with low viscosity, and so it runs freely.
Liquids such as honey and maple syrup both have high viscosity, making them thick and slow moving. By studying the viscosity of lava, scientists can determine how dangerous an active volcano might be. It is the amount of silica in the lava that determines its viscosity. A volcano with small amounts of silica has a low viscosity. It is swift moving and able to destroy surrounding areas quickly without much time for evacuation.