All Study Guides Volcanology Unit 1
🌋 Volcanology Unit 1 – Volcanology: Earth's Fiery StructureVolcanology explores Earth's fiery underbelly, studying how volcanoes form, behave, and impact our world. From shield volcanoes to explosive stratovolcanoes, this field examines diverse volcanic structures, eruption types, and the complex interplay of magma composition and behavior.
Volcanic hazards like pyroclastic flows and lahars pose significant risks to communities. Scientists use various monitoring techniques to predict eruptions and assess risks. Volcanoes also play a crucial role in shaping landscapes, influencing climate, and even creating fertile soils that support life.
Key Concepts and Terminology
Volcanology studies the formation, behavior, and effects of volcanoes and volcanic phenomena
Magma molten rock beneath Earth's surface consists of liquid rock, crystals, and dissolved gases
Lava magma that reaches the surface during a volcanic eruption can flow and solidify into various formations
Volcanic arc chain of volcanoes formed by subduction of oceanic plates beneath continental or other oceanic plates (Aleutian Islands)
Pyroclastic flow fast-moving, ground-hugging avalanche of hot ash, pumice, rock fragments, and volcanic gas (Mount Vesuvius eruption in 79 AD)
Lahar volcanic mudflow or debris flow composed of volcanic ash, rock, and water from a volcano (Nevado del Ruiz eruption in 1985)
Can be triggered by heavy rainfall, rapid snowmelt, or collapse of a volcanic dam
Caldera large circular depression formed by the collapse of a volcano's summit or the emptying of its magma chamber (Yellowstone Caldera)
Fumarole opening in or near a volcano that emits steam and volcanic gases (Sulphur Springs in St. Lucia)
Types of Volcanoes and Eruptions
Shield volcanoes broad, gently sloping volcanoes built from fluid lava flows (Mauna Loa in Hawaii)
Produce effusive eruptions with low-viscosity lava that can flow great distances
Stratovolcanoes tall, conical volcanoes composed of layers of lava, ash, and pyroclastic debris (Mount Fuji in Japan)
Often associated with explosive eruptions due to high-viscosity lava and gas buildup
Cinder cone volcanoes small, steep-sided volcanoes built from accumulations of ejected lava fragments (Parícutin in Mexico)
Lava domes rounded, steep-sided mounds formed by viscous lava piling up around a volcanic vent (Lassen Peak in California)
Phreatic eruptions steam-driven explosions that occur when water comes into contact with hot rock or magma (Taal Volcano in the Philippines)
Plinian eruptions violent, explosive eruptions characterized by tall eruption columns and widespread ash dispersal (Mount Vesuvius eruption in 79 AD)
Strombolian eruptions moderate-sized explosions that eject incandescent cinders, lapilli, and lava bombs (Stromboli in Italy)
Named after the Italian volcano Stromboli, known for its frequent, mildly explosive eruptions
Volcanic plug solidified magma that fills and seals the conduit of a volcano (Ship Rock in New Mexico)
Lava tubes cave-like structures formed by the drainage of lava beneath the hardened surface of a lava flow (Thurston Lava Tube in Hawaii)
Lava plateaus extensive, flat areas of solidified lava formed by large-scale effusive eruptions (Columbia River Basalt Province)
Volcanic necks erosional remnants of the central vent or plug of a volcano (Devil's Tower in Wyoming)
Columnar jointing distinctive pattern of hexagonal columns formed by the contraction of cooling lava (Giant's Causeway in Northern Ireland)
Maar broad, shallow volcanic crater formed by a phreatic or phreatomagmatic eruption (Crater Elegante in Mexico)
Often filled with water to form a crater lake
Fumarolic fields areas with numerous fumaroles and hydrothermal activity (Bumpass Hell in Lassen Volcanic National Park)
Lava trees vertical molds formed when lava flows around and solidifies around tree trunks (Lava Tree State Park in Hawaii)
Magma Composition and Behavior
Magma composition influences volcanic behavior and eruption style through variations in silica content, viscosity, and gas content
Mafic magma low-silica, high-temperature magma that produces fluid lava flows and effusive eruptions (basaltic magma)
Associated with shield volcanoes and lava plateaus
Felsic magma high-silica, lower-temperature magma that generates viscous lava flows and explosive eruptions (rhyolitic magma)
Often found in stratovolcanoes and lava domes
Magma viscosity measure of a magma's resistance to flow determined by silica content, temperature, and dissolved gas content
Higher viscosity magmas tend to trap gases, leading to explosive eruptions
Magma differentiation process by which magma composition evolves due to crystallization and removal of minerals (fractional crystallization)
Magma mixing blending of two or more magmas of different compositions, which can trigger volcanic eruptions
Volatiles dissolved gases in magma (water vapor, carbon dioxide, sulfur dioxide) that exsolve and expand as magma rises and decompresses
Contributes to the explosivity of volcanic eruptions
Magma chamber large underground pool of magma beneath a volcano that feeds volcanic eruptions (Yellowstone magma chamber)
Monitoring and Predicting Volcanic Activity
Seismic monitoring detection and analysis of earthquakes and seismic waves to assess volcanic activity and potential eruptions
Volcanic tremor continuous, rhythmic seismic signal often preceding or accompanying volcanic eruptions
Ground deformation measurements of changes in the shape of a volcano's surface using GPS, tiltmeters, and satellite radar interferometry (InSAR)
Inflation of a volcano can indicate magma accumulation and increased eruption potential
Gas monitoring sampling and analysis of volcanic gases to determine changes in magma chemistry and degassing (sulfur dioxide, carbon dioxide)
Increased gas emissions often precede volcanic eruptions
Remote sensing use of satellite imagery, thermal imaging, and other techniques to detect surface temperature changes and ash plumes
Lahar detection systems networks of acoustic flow monitors, trip wires, and rain gauges to provide early warning of lahars
Eruption precursors observable phenomena that often precede volcanic eruptions (increased seismicity, ground deformation, gas emissions)
Used in combination to assess the likelihood and timing of an eruption
Hazard mapping creation of maps that delineate areas potentially affected by volcanic hazards (lava flows, pyroclastic flows, ash fall)
Essential for risk assessment and emergency planning
Hazards and Risk Assessment
Pyroclastic flows fast-moving, ground-hugging avalanches of hot ash, pumice, rock fragments, and volcanic gas (Mount Pelee eruption in 1902)
Can travel at speeds up to 700 km/h and reach temperatures of 1,000°C
Lava flows streams of molten rock that pour from a volcano during an effusive eruption (Kilauea eruption in 2018)
Can destroy infrastructure and reshape landscapes but generally move slowly enough for people to evacuate
Volcanic ash fine particles of pulverized rock and glass ejected during an explosive eruption (Mount St. Helens eruption in 1980)
Can cause respiratory problems, damage aircraft engines, and collapse roofs under heavy accumulation
Volcanic gases emissions of water vapor, carbon dioxide, sulfur dioxide, and other gases from volcanoes
Can cause acid rain, air pollution, and contribute to climate change
Lahars volcanic mudflows or debris flows composed of volcanic ash, rock, and water from a volcano (Nevado del Ruiz eruption in 1985)
Can travel great distances, inundate valleys, and destroy infrastructure
Volcanic tsunamis waves generated by the displacement of water during a volcanic eruption or flank collapse (Krakatoa eruption in 1883)
Volcanic edifice collapse sudden failure and downslope movement of a volcano's flank or summit (Mount St. Helens eruption in 1980)
Can generate debris avalanches, lahars, and lateral blasts
Risk assessment evaluation of the potential impacts and likelihood of volcanic hazards on communities and infrastructure
Considers factors such as population exposure, vulnerability, and resilience
Environmental and Climate Impacts
Volcanic ash and aerosols can affect climate by reflecting solar radiation and promoting atmospheric cooling (Mount Pinatubo eruption in 1991)
Sulfur dioxide emissions can lead to the formation of sulfuric acid droplets in the stratosphere
Volcanic CO2 emissions contribute to greenhouse gas concentrations and long-term climate change
Volcanoes release an estimated 180 to 440 million tonnes of CO2 per year
Volcanic eruptions can cause short-term regional cooling and global temperature fluctuations (Laki eruption in 1783)
Injection of ash and sulfur dioxide into the upper atmosphere can disrupt weather patterns
Volcanic soils weathering of volcanic ash and rocks can create fertile soils rich in nutrients (Andisols)
Support diverse ecosystems and agricultural productivity in volcanic regions
Hydrothermal systems networks of hot springs, geysers, and fumaroles associated with volcanic activity (Yellowstone hydrothermal system)
Host unique thermophilic microbial communities and provide geothermal energy resources
Volcanic lakes water-filled volcanic craters that can host endemic species and provide water resources (Crater Lake in Oregon)
Can also pose hazards such as lake overturn and limnic eruptions due to dissolved gas accumulation
Volcanic island formation creation of new land by submarine or subaerial volcanic eruptions (Surtsey in Iceland)
Contributes to the growth and evolution of oceanic islands and archipelagos
Notable Volcanoes and Case Studies
Mount Vesuvius (Italy) infamous for its catastrophic eruption in 79 AD that buried the Roman cities of Pompeii and Herculaneum
Provides a valuable archaeological record of Roman life and the impacts of volcanic eruptions
Krakatoa (Indonesia) explosive eruption in 1883 generated devastating tsunamis and global climate effects
Collapse of the volcanic edifice created a 6-km-wide caldera and new volcanic islands
Mount St. Helens (USA) major eruption in 1980 featuring a massive debris avalanche, lateral blast, and ash column
Significant ecological disturbance and recovery, now a natural laboratory for studying volcanic processes
Kilauea (Hawaii) one of the world's most active volcanoes, known for its continuous effusive eruptions and lava flows
Eruptions have added over 500 acres of new land to the island of Hawaii since 1983
Yellowstone Caldera (USA) largest volcanic system in North America, characterized by extensive hydrothermal activity and geysers
Potential for future supereruptions, though the likelihood is low on human timescales
Mount Pinatubo (Philippines) major eruption in 1991 that injected large amounts of sulfur dioxide into the stratosphere
Caused global temperature drop of 0.6°C and disrupted global weather patterns for several years
Eyjafjallajökull (Iceland) eruption in 2010 that disrupted air travel across Europe due to the widespread dispersal of volcanic ash
Highlighted the vulnerability of modern transportation systems to volcanic hazards
Nevado del Ruiz (Colombia) eruption in 1985 triggered destructive lahars that killed over 23,000 people in the town of Armero
Emphasized the importance of volcano monitoring, hazard mapping, and early warning systems