Volcanism and Volcano Structures

Volcanism, Magma, and Geothermal Energy

• Volcanism is the process of molten rock (magma) erupting onto a planet's surface. It occurs when internal heat causes surface rocks to melt. This often happens where tectonic plates move.
• Volcanoes are natural openings in the Earth's surface where molten rock, gases, smoke, and ash are ejected. They contain internal parts like magma reservoirs (magma chambers), craters (depression above the vent), caldera (large depression from collapse), throat (volcano entrance), conduit (underground magma passage), and lava flow (molten rock on the surface).

Internal Parts of a Volcano

• Magma Reservoir: A large pool of liquid rock beneath the surface, storing magma before eruption
• Crater: A bowl-shaped depression above the volcano's vent.
• Caldera: A large depression formed when a volcano erupts and its summit collapses

Types of Volcanoes

• Active Volcano: Showing signs of eruption in the last 50-10,000 years
• Inactive (Dormant) Volcano: Erupted previously and not erupted in 10,000 years
• Extinct Volcano: No record of eruption, and not anticipated to erupt

Parts of a Volcano (External Features)

• Summit: Highest point
• Flank: Sloping side of the volcano
• Base: Bottom part of the volcano
• Vent: Opening where magma, gases, and other materials erupt
• Ash Cloud: Plume of volcanic material during eruption
• Solidified Lava: Hardened/stacked lava from previous eruptions
• Ash: Collection of solid particles from volcanic eruptions

Types of Volcanoes (Based on Shape)

• Composite Volcano (Stratovolcano): Tall peak, alternating layers of lava and cinders, sloped structure
• Shield Volcano: Largest volcanic structure, formed by accumulated layers of lava, broad gently sloped cone shape
• Cinder Cone Volcano: Narrow base, steep slope, formed from cinders and ash, characterized by short-lived explosive eruptions

Volcanic Eruptions

• Phreatic (Steam-blast or Hydrothermal) Eruption: Short-lived eruption created by water interaction with hot rock
• Strombolian Eruption: Periodic, weak to violent eruptions characterized by lava fountains
• Vulcanian Eruption: Taller eruptions, columns reaching 20 km high, pyroclastic flow, ashfall
• Plinian Eruption: Excessively explosive eruption creating large amounts of gas and pyroclastic materials

Magma

• Molten or partially molten rock located beneath the Earth's surface; different compositions define different types (mafic, intermediate, felsic)
• Vary in silica content (low in mafic, high in felsic) which affects viscosity, appearance, and explosiveness during eruption.

Lava

• Magma that reaches the Earth's surface

Geothermal Energy

• Renewable energy derived from the Earth's internal heat
• Geothermal power plants use the heat to produce steam, which powers turbines to generate electricity
• Geothermal heat pumps utilize constant underground temperatures to efficiently heat or cool buildings.

Geothermal Power Plants

• Heat Source: Magma located deep beneath the Earth's crust
• Reservoir: A permeable rock layer storing hot water
• Caprock: A layer that prevents water from escaping the reservoir
• Water (Working Fluid): Acts as a medium within the cycle
• Production Well: Pumps hot water upward
• Turbine: Spins due to steam from hot water, turning the generator
• Generator: Converts mechanical energy (from turbine) to electrical energy
• Cooling Tower: Condenses steam back into water, returning it to the ground

Factors Affecting Climate

• Latitude (horizontal): Sun's rays strike at different angles, impacting temperature variances, tropical/temperate/polar zones result
• Altitude: Higher places generally have lower temperatures
• Ocean Currents: The movement of water globally, transporting heat and affecting temperature
• Distance from Bodies of Water: Coastal areas tend to have more moderate temperatures compared to inland areas
• Topography: Landforms & elevation differences affect local weather patterns
• Weather: The short-term state of the atmosphere, including temperature, precipitation, humidity, and wind (Meteorology - study of weather)
• Climate: Overall weather patterns over a long period of time (Climatology - study of long-term climate)

Greenhouse Effect

• A natural warming process where greenhouse gases (CO2, CH4, N2O, HFC, SF6, PFC, and water vapor) trap heat from Earth.
• This maintains the planet's temperature suitable for life.
• Excessive amount of greenhouse gases from human activities (anthropogenic) results in enhanced greenhouse effect, leading to global warming and climate change

Climate Change

• Long-term shifts in temperature and weather patterns, influenced by factors such as natural occurrences and human activities.
• Human activities are increasing greenhouse gas quantities resulting in global warming.