This Word file is a blank table that students can use to organize their understanding of lava chemistry and properties. The table is designed to be used as part of the Modeling Lava Viscosity Demonstration. The properties of four types of lava (rhyolite, dacite, andesite, and basalt) and the volcanoes that from by eruption of these lavas can be briefly described and / or drawn on the table. The answer key is provided in the completed table “Modeling Lava Viscosity – Table of Volcanic Eruption Styles Answers”.
Bonnie Magura (Jackson Middle School, Portland, Oregon) developed this classroom demonstration of lava viscosity. The viscosity of lava that erupts from a volcano controls the shape of the resulting volcano. In turn, the silica (SiO2) content of the erupting lava controls its viscosity, with higher silica (SiO2) content resulting in higher viscosity. (Remember that low viscosity means “runny” lava that can flow down a gentle slope whereas high viscosity means “sticky” lava flows slowly and can form a steep-sided volcano.) By mixing different syrups, a variety of “lavas” with contrasting viscosities can be made. This demonstration invites students to join their teacher as (s)he melts different rocks with different silica (SiO2) contents to form “lavas” with contrasting viscosities. If you are a teacher with a flare for drama, this is your activity!
This activity allows teachers to demonstrate how magma intrudes the rocks beneath a volcano, sometimes leading to an eruption of lava from the summit or flanks of the volcano. The gelatin volcano is transparent so students can observe the process of intrusion as the “magma” shoulders surrounding rocks aside to form dikes (vertical igneous rock bodies in the subsurface) or sills (subhorizontal igneous rock layers in the subsurface). The setup time for this classroom demonstration is significant but the payoff can be dramatic! The accompanying video demonstration by Roger Groom (Mt Tabor Middle School, Portland, Oregon) shows how the gelatin volcano works to help students understand the inner workings of a volcano.
Some volcanic craters form by the violent expulsion of magma (liquid rock) when it reaches Earth’s surface where liquid rock is referred to as “lava”. However, many volcanic craters form by collapse of the rock near the summit of the volcano. When magma pushes up through Earth’s crust, it must displace the surrounding and overlying rocks as it works its way toward the surface. When magma enters a shallow reservoir beneath a volcano, the ground above that magma chamber can “inflate,” pushing the ground upward and outward away from the center of the volcano. When an eruption occurs, magma is removed from the shallow reservoir beneath a volcano and the volcano can “deflate” with the ground sinking downwards and inward toward the center of the volcano. This inflation-deflation process can fracture and weaken the ground surrounding and above the magma chamber. The fractured rocks can sink to form a round or elliptical depression of the ground called a “caldera”. The formation of a caldera can be a catastrophic process that accompanies a violent eruption (e.g. geologically-recent eruptions of Yellowstone in Wyoming or Long Valley in eastern California) or a relatively gentle volcanic eruption (e.g. eruptions of basaltic lavas from Hawaiian volcanoes). This flour box demonstration takes learners through the stepwise process of “predicting” what you might see before and after a caldera collapse.
This 5-page PDF provides a brief introduction to the primary methods of monitoring volcanoes. Approaches to monitoring ground deformation on and around volcanoes are described along with methods for monitoring earthquake activity beneath a volcano and monitoring volcanic gas emissions.
Carbon dioxide (CO2) is a major volcanic gas. It is invisible, odorless, and heavier than air. CO2 can accumulate in low-lying areas near volcanoes where unsuspecting people can be asphyxiated by walking into the invisible cloud of CO2 gas. This inquiry-based demonstration shows how CO2 gas produced from vinegar and baking soda displaces oxygen and sequentially snuffs candles representing different elevations.
The shape of the ground surface on or around a volcano sometimes precedes volcanic eruptions. Monitoring the shape of volcanoes has become an important component of volcano monitoring programs. This animation explains the principles of GPS and tiltmeter monitoring of volcanoes. The animation was developed by the Mt St Helens Institute, US Geological Survey Johnston Ridge Observatory, IRIS, and EarthScope.
This animation was developed by the Educational Multimedia Visualization Center of the Department of Earth Science, University of California at Santa Barbara, under the direction of Professor Tanya Atwater. The animation shows how subduction of an oceanic plate beneath a continental plate can produce an accretionary wedge of oceanic sediment and “lights the lava lamp” by generating magma in the asthenospheric mantle above the subducting plate.
Earthquakes of small magnitude and shallow depth often occur beneath volcanoes that are approaching eruption. These earthquakes are caused by heating of rocks beneath the volcano as magma works its way up into shallow chambers beneath the volcano and by pressure changes within the rising magma. This animation explains the principles of seismic monitoring of volcanoes. The animation was developed by the Mt St Helens Institute, US Geological Survey Johnston Ridge Observatory, IRIS, and EarthScope.
Gases such as CO2 and SO2 are contained within magma that rises beneath volcanoes. Gas emissions often increase and change composition prior to volcanic eruptions. monitoring of gas emissions has become an important component of volcano monitoring programs. This animation explains the principles of volcanic gas monitoring using ultraviolet spectrometry. The animation was developed by the Mt St Helens Institute, US Geological Survey Johnston Ridge Observatory, IRIS, and EarthScope.