2.3 Volcanic Hazards and Predicting Volcanic Eruptions
Volcanic Hazards
Lava and Magma viscosity can lead to a wide range of volcanic hazards. You should be familiar with some of these from your assigned reading already, but let’s go over the terminology again.
Tephra: Pieces of rock ejected by a volcanic eruption.
Volcanic Ash: Fine-grained particles of tephra that can accumulate in large amounts and destabilize structures or cause silicosis.
Lava Bombs: Large chunks of semi-molten tephra (at least 6.4 cm) that fly through the air during an eruption.
Lahar: A sudden mudflow that can occur along the slope of a volcano.
Pyroclastic Flow: An extremely fast-moving cloud of molten-hot gas and ash.
Volcanic Gases: Toxic fumes that cause respiratory problems, but are known to combine with water in the atmosphere (in the case of H2S) and form aerosols that block the sun and temporarily cool the climate for a period of a year or years.
We know that volcanoes can be deadly. But how do we avoid their eruptions? There are millions of people who live near active volcanoes in the world, and moving away from their homes or deserting a successful town or city is not an option. Therefore, these people rely on the measurements performed by scientists called volcanologists, who study the active volcanoes around the world, to predict when a certain volcano is showing signs of an imminent eruption.
How can we tell a volcano is getting ready to erupt? Usually, the volcano will start to show signs of unrest such as ground deformation – where the magma chamber starts to bulge as the magma moves beneath the surface, changes in gas emission, steam blasts from crevices near the volcano as groundwater heats up, and importantly, seismic (i.e., earthquake) activity. Check out the video below, and answer the questions that appear during it!
IMPORTANT: Make sure you watch the ENTIRE video, answer all the questions, and click on “SUBMIT ANSWERS” at the end to earn credit for the activity below!
The image below shows different methods that a volcanologist can use to monitor an active volcano.
The eruption at La Soufriere Hills in St. Vincent is an important example of how geoscientists cooperate with the local government to alert the public about potential eruptions.
