11-VolcanoesCV (1)

Module 3: Geosphere

Overview of Volcanoes, Resources, & Hazards

• Volcanoes can pose various hazards and play significant roles in shaping Earth's environment.

• Key topics covered include:

  • Minerals & Mineral Resources

  • Plate Tectonics & Life

  • Why do people live near volcanoes?

  • Local and regional hazards associated with volcanoes

  • Primary gases released during eruptions and their environmental effects

  • The rock cycle, sedimentary rocks, and the carbon cycle

  • Weathering and soils

Active Volcano Locations

• Most volcanic hazards are concentrated around active volcano locations, where eruptions are more likely to occur.

Benefits of Living Near Volcanoes

• Approximately 800 million people live in proximity to volcanoes due to several advantages:

  • Access to coastal resources, including freshwater, fish, and favorable climates.

  • Weathering of volcanic rock creates nutrient-rich soils, promoting fertile farming opportunities.

  • Volcanic activity is responsible for concentrating many economic and strategic minerals, providing resources.

  • Example: Hydrothermal regions, such as Yellowstone National Park, showcase the benefits of volcanic phenomena for agriculture and resource extraction.

Volcano-related Hazards

Local Hazards

• Lava Flows: Typically affect areas close to the volcano and are more common in oceanic environments.

• Pyroclastic Flows: Extremely dangerous, these flows can extend beyond the vicinity of the volcano and are prevalent in continental settings.

Regional Hazards

• Volcanic Ash: Can become airborne and travel long distances due to atmospheric circulation.

• Lahars: Occur when volcanic material mixes with water from heavy rains or melting snow, creating destructive mudflows.

Atmospheric Hazards

• Volcanic eruptions can modify the atmosphere's composition for extended periods (months to years).

• Effects can include global climate changes and air quality issues.

Volcano Hazard Maps Overview

• Different volcano hazard zones are identified based on their proximity to a volcano and the type of hazards they face:

  • Near-Volcano Hazards: Include lava flows, pyroclastic flows, thick tephra, lahars, ballistic projectiles, and rock falls.

  • Regional Hazards: Encompass broader impacts like lahars in valleys and widespread ash dispersal from eruptions.

Yellowstone Supervolcano Insights

• Yellowstone has experienced a range of volcanic activities, classified by frequency and destructiveness:

  • Hydrothermal explosions and strong earthquakes are common, while caldera-forming eruptions occur infrequently (1-2 per million years).

Gaseous Emissions from Volcanoes

• Two primary volcanic gases:

  • Water Vapor

  • Carbon Dioxide (CO2): Both gases can significantly impact climate when released into the atmosphere.

  • Debate exists regarding whether volcanoes release more CO2 than human activities.

Atmospheric Effects of Volcanic Sulfur Dioxide (SO2)

• In the atmosphere, SO2 can convert to sulfuric acid droplets, forming aerosols that reflect sunlight:

  • High albedo of aerosols leads to temporary cooling effects on climate.

  • Longer-term atmospheric presence occurs when aerosols are released into the stratosphere.

Historical Case Study: Eruption of Tambora (1816)

• Tambora's eruption was one of the largest historic eruptions, leading to:

  • Global cooling phenomena termed "The Year without Summer" in 1816.

  • Severe weather anomalies: Snowfalls in summer, leading to crop failures and widespread famine affecting up to 200,000 people in Europe alone.

Review of Key Concepts

• Types of Impacts: Distinguish between local, regional, and global impacts of volcanoes, with concrete examples for each type.

• Lava Composition: Discuss how the composition of lava affects eruption styles, differentiating between effusive and explosive eruptions.

• Geographic Influence: Consider how the location of volcanoes (continental versus oceanic) influences their behavior.

• Gaseous Emissions: Reiterate significance of sulfur dioxide and carbon dioxide in relation to climate effects.

• Historical Context: Analyze past volcanic activities in terms of their influences on climate change.

• Human Habitation: Reflect on the reasons why people continue to inhabit areas near volcanoes despite the hazards.

Local, Regional, and Global Impacts of Volcanoes:

• Local Impacts:

  • Lava Flows: Affect areas close to the volcano; common in oceanic environments.

  • Pyroclastic Flows: Extremely dangerous; can extend beyond the vicinity of the volcano, prevalent in continental settings.

• Regional Impacts:

  • Volcanic Ash: Can travel long distances due to atmospheric circulation.

  • Lahars: Destructive mudflows occurring when volcanic material mixes with water.

• Global Impacts:

  • Climate Change: Eruptions can lead to temporary cooling effects due to sulfuric acid aerosols reflecting sunlight.

  • Historical Example: The eruption of Tambora (1816), which caused "The Year without Summer," leading to severe weather anomalies and crop failures affecting 200,000 people in Europe.

Experience of a Volcanic Hazard:

• Individuals may choose to experience lava flows for their visibility and predictability compared to other hazards like pyroclastic flows or lahars, which are much more dangerous and sudden.

Lava Composition and Eruption Styles:

• Effusive Eruptions: Characterized by low-viscosity lava flows that allow gases to escape easily.

• Explosive Eruptions: Caused by high-viscosity lava that traps gases until pressure builds to an explosive level.

• The lava composition directly impacts the behavior of eruptions.

Geographic Influence on Eruption Styles:

• Continental Volcanoes: Often have more explosive activity due to higher viscosity lava.

• Oceanic Volcanoes: Tend to have effusive eruptions with less viscous lava, leading to lava flows rather than explosive activity.

Gaseous Emissions from Volcanoes:

• SO2 & CO2 Release:

  • Important for understanding climate effects.

• Sulfuric Acid Aerosols:

  • Form in the atmosphere, reflect sunlight, and cause temporary cooling effects.

Current Volcanic Activity and Climate Change:

• While today's volcanic activity is not as intense, past eruptions have contributed to significant climate changes.

CO2 Emissions Comparison:

• Human activities currently release more CO2 into the atmosphere than volcanoes.

Human Habitation Near Volcanoes:

• Despite hazards, about 800 million people live near volcanoes due to advantages such as nutrient-rich soils, access to freshwater, fish, and favorable climates.