1 / 42

Chapter 5 Volcanoes and Other Igneous Activity

The Nature of Volcanic Eruptions. Factors determining the

silvio
Download Presentation

Chapter 5 Volcanoes and Other Igneous Activity

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. Chapter 5 Volcanoes and Other Igneous Activity

    2. The Nature of Volcanic Eruptions Factors determining the violence or explosiveness of a volcanic eruption Temperature of the magma Composition of the magma Dissolved gases in the magma The above three factors actually control the viscosity of a given magma which in turn controls the nature of an eruption

    3. The Nature of Volcanic Eruptions Viscosity is a measure of a materials resistance to flow Factors affecting viscosity Temperature - Hotter magmas are less viscous Composition - Silica (SiO2) content Higher silica content = higher viscosity (e.g., felsic lava such as rhyolite) Lower silica content = lower viscosity or more fluid-like behavior (e.g., mafic lava such as basalt)

    4. The Nature of Volcanic Eruptions Factors affecting viscosity continued Dissolved Gases Gas content affects magma mobility Gases expand within a magma as it nears the Earths surface due to decreasing pressure The violence of an eruption is related to how easily gases escape from magma

    5. The Nature of Volcanic Eruptions Factors affecting viscosity continued In Summary Fluid basaltic lavas generally produce quiet eruptions Highly viscous lavas (rhyolite or andesite) produce more explosive eruptions

    6. Materials extruded from a volcano Lava Flows Basaltic lavas are much more fluid Types of basaltic flows Pahoehoe lava (resembles a twisted or ropey texture) Aa lava (rough, jagged blocky texture)

    7. A Pahoehoe lava flow

    8. A Typical aa flow

More Related