Dissolved Gases

Definition

Dissolved gases refer to gases such as water vapor, carbon dioxide, sulfur dioxide, and others that are held within magma in a dissolved state under high pressure. These gases play a crucial role in magma's behavior and composition, influencing how it erupts and the type of volcanic activity that occurs. The concentration of these gases can vary significantly based on the magma's source and conditions during its ascent to the surface.

5 Must Know Facts For Your Next Test

1. Dissolved gases are critical in determining the eruptive style of a volcano; high gas content can lead to explosive eruptions, while low gas content typically results in effusive eruptions.
2. As magma rises towards the surface, the decrease in pressure allows dissolved gases to come out of solution, forming bubbles that expand and can drive explosive volcanic activity.
3. Carbon dioxide and water vapor are among the most abundant dissolved gases in magma, but their concentrations can vary widely depending on the geological setting.
4. Sulfur dioxide emissions from volcanoes are closely monitored because they can impact air quality and climate patterns, making them important indicators of volcanic activity.
5. The amount and type of dissolved gases present in magma can help geologists understand its source, the processes it underwent during ascent, and predict future volcanic behavior.

Review Questions

• How do dissolved gases influence the eruptive behavior of different types of magma?
  • Dissolved gases significantly influence how magma behaves when it erupts. Magma with a high concentration of dissolved gases tends to be more explosive because the rapid expansion of gas bubbles during an eruption can lead to violent fragmentation. Conversely, magma with lower gas content tends to erupt more effusively, flowing out more gently. Understanding the gas content helps volcanologists predict whether an eruption will be explosive or non-explosive.
• Discuss how exsolution of dissolved gases contributes to volcanic eruptions and the potential hazards associated with this process.
  • Exsolution is a critical process where dissolved gases in magma escape as it ascends due to decreasing pressure. This can create gas bubbles that expand rapidly, contributing to explosive eruptions. Such eruptions can pose significant hazards, including pyroclastic flows, ashfall, and volcanic gases that can impact air quality and climate. Monitoring these gas emissions helps scientists assess eruption risks and implement safety measures.
• Evaluate the role of dissolved gases in understanding volcanic systems and their implications for predicting future eruptions.
  • Dissolved gases provide vital information about the characteristics and behavior of volcanic systems. By analyzing gas compositions and concentrations in both magmas and emissions, scientists can gain insights into the processes occurring beneath the surface. This knowledge helps develop models for predicting future eruptions by identifying changes in gas emissions that may signal an impending eruption. Such evaluations are crucial for effective monitoring and risk management strategies for communities near volcanoes.

Related terms

Magma Viscosity: The measure of a magma's resistance to flow, which is affected by its composition and temperature, as well as the amount of dissolved gases present.

Volcanic Gas Emissions: The release of gases from a volcano, which can include water vapor, carbon dioxide, sulfur dioxide, and other compounds, often indicating the potential for eruptions.

Exsolution: The process by which dissolved gases escape from magma as it rises and loses pressure, leading to bubble formation and potentially explosive eruptions.