Volcanology and Volcano Hazards

These flashcards cover the essential vocabulary and definitions related to volcanic hazards and eruption signs as presented in the lecture notes.

Volcano

A mountain or hill, typically conical, having a crater or vent through which lava, rock fragments, hot vapor, and gas are erupted from the earth's crust.

Mafic Magma

Magma that is rich in iron (Fe) and magnesium (Mg), allowing gases to escape easily, resulting in a quiet lava flow.

Felsic Magma

Magma that is rich in silicon (Si) and oxygen (O), which tends to trap volcanic gases, leading to greater pressure and explosive eruptions.

Tephra Fall

Volcanic rock and lava materials that are ejected into the air by explosion or carried by an eruption column's gases.

Pyroclastic Density Currents (PDCs)

Mixtures of fragmented volcanic particles, gases, and ash that rush down volcanic slopes at high speeds.

Lahar

Rapidly flowing thick mixtures of volcanic sediments and water, often triggered by intense rainfall or the melting of glacier ice.

Volcanic Tsunami

Waves caused by the displacement of water in caldera lakes or seas as a result of volcanic activity, such as explosions or flank collapses.

Volcanic Gas

Dissolved components of magma released into the atmosphere during eruptions, such as H{2}O, CO{2}, and SO_{2}.

Ground Deformation

Changes in the ground surface, such as swelling or sinking, that may indicate volcanic activity and magma movement beneath the surface.

Seismic Activity

An increase in volcanic earthquakes that may signify magma or gas moving through the volcanic conduit.

Asphyxiation

A lack of oxygen caused by the displacement of air by volcanic gases (like CO_{2}), which can be lethal to humans and animals.

Respiratory Health Effects

Negative health impacts caused by inhaling volcanic ash, such as the exacerbation of existing lung diseases and irritation of the airways.

Ballistic Projectiles

Tephra (volcanic fragments) that follows a projectile path as they are expelled forcefully from a volcanic vent.

Volcanic Ejecta

A general term for materials such as molten lava, gas, and ashes expelled during a volcanic eruption.

Volcanic Hazard Map

A map indicating the specific areas that may experience various hazards from volcanic activity, used for disaster preparedness.

Active Volcano

Volcanoes that have erupted within the last 600 years or have documented activity in historical records.

Potentially Active Volcano

Young-looking volcanoes with no historical or analytical records of eruption but showing signs of recent geological activity.

Inactive Volcano

Volcanoes with no recorded eruptions that have experienced significant erosion and weathering over long geological periods.

Lava Flow

Rivers of molten rock moving downslope from a volcanic vent, varying in speed depending on viscosity.

Volcanic Ash

Fine particles of pulverized rock, minerals, and volcanic glass ejected into the air during explosive eruptions.

Hydrogen Fluoride (HF)

A toxic volcanic gas (HF) that can irritate skin, eyes, and mucous membranes and contaminate local water supplies.

Carbon Dioxide (CO2)

A colorless, odorless gas (CO_{2}) released by volcanoes that can cause asphyxiation in high concentrations by displacing oxygen.

Sulfur Dioxide (SO2)

A colorless gas (SO_{2}) with a pungent odor that can cause respiratory irritation and contribute to the formation of acid rain.

Tilt Meter

A sensitive instrument used to detect even the slightest changes in the slope of a volcano's ground surface, indicating pressure changes below.

Global Positioning System (GPS)

A satellite-based system used for monitoring precise changes in the horizontal and vertical position of points on a volcano.

Electronic Distance Measurement (EDM)

A monitoring technique using laser light to measure distance changes between 2 fixed points to detect ground swelling or contraction.

Eruptive Signs

Specific indicators such as increased seismic activity, gas emissions, and ground deformation that suggest a volcano may be nearing an eruption.

Early Warning Signals

Official notifications provided by monitoring authorities to warn communities about volcanic activity and potential hazards.

Evacuation Plan

A pre-arranged strategy set in place by communities to ensure safety and orderly movement in the event of a volcanic eruption.

Pyroclastic Flow

A fast-moving, destructive current of hot gas and volcanic matter that flows down the slopes of a volcano.

Volcanic Dome

A steep-sided, mound-shaped protrusion resulting from the slow extrusion of highly viscous lava from a volcanic vent.

Geochemistry Monitoring

The practice of analyzing the chemical composition of volcanic gases and spring water to predict potential changes in volcanic activity.

Stratovolcano

A tall, steep-sided volcano built from multiple layers of viscous lava and tephra, typically associated with explosive eruptions.

Shield Volcano

A broad, gently sloping volcano built almost entirely by the repetitive flow of low-viscosity mafic lava.

Cinder Cone

A small, steep-sided volcano formed from blobs of congealed lava and rock fragments ejected from a single vent.

Caldera

A large, circular depression formed when the roof of a magma chamber collapses following a massive, emptying eruption.

Magma

Molten or semi-molten rock material located beneath the Earth's surface, containing dissolved gases and crystals.

Phreatic Eruption

A steam-driven explosion caused by the interaction of groundwater with hot volcanic rock without the ejection of new magma.

Volcanic Explosivity Index (VEI)

A relative scale from 0 to 8 used to measure and compare the explosive magnitude and volume of volcanic eruptions.

Fumarole

An opening in or near a volcano through which steam and volcanic gases like sulfur dioxide (SO_{2}) are emitted into the atmosphere.