Volcanoes Science Review PDF

How to Monitor Volcanoes Volcano Volcanologists -​ is an opening in the Earth’s crust where magma, gases, and ash escape to the surface. When -​ Volcanologists study volcanoes to predict magma erupts,...

How to Monitor Volcanoes Volcano Volcanologists -​ is an opening in the Earth’s crust where magma, gases, and ash escape to the surface. When -​ Volcanologists study volcanoes to predict magma erupts, it becomes lava and cools to form eruptions and minimize risks. new land. Volcanoes can be found on land or under the ocean and are mostly located along Parts of a Volcano tectonic plate boundaries. ​ Magma – Molten rock beneath Earth’s surface. How Volcanoes Are Formed ​ Lava – Magma that has erupted onto the surface. ​ Crater – Circular depression at the top of a 1.​ Intrusion (Formation Beneath the Surface) volcano. ​ Vent – The main opening where magma and Intrusion happens when magma pushes into existing rock gases escape. layers but does not erupt. Instead, it cools and solidifies ​ Main Vent – The primary passageway for underground, forming: magma. ​ Sills – Horizontal sheets of solidified magma ​ Summit – The peak of the volcano. between rock layers. ​ Flank – The side of the volcano. ​ Dikes – Vertical intrusions that cut across rock ​ Parasitic Cone – Smaller cones that form on the layers. main volcano due to additional vents. ​ Batholiths & Laccoliths – Large underground ​ Conduit – The underground passage that carries magma reservoirs that may later feed eruptions. magma. ​ Sill – A horizontal intrusion of magma. 2. Extrusion (Eruption Onto the Surface) ​ Ash Fragments – Tiny rock particles ejected from eruptions. -​ Extrusion happens when magma breaks through ​ Ash Cloud – A cloud of ash and gas from the Earth’s crust and erupts as lava, ash, or explosive eruptions. gases. The lava cools and builds up layers over ​ Magma Chamber – A large underground time, forming volcanic mountains or islands. reservoir of magma. ​ Lava Flow – The movement of erupted lava down the slope. Plate Boundaries and Volcanoes ​ Secondary Vent – Additional openings for magma. 1. Convergent Boundaries (Destructive Boundaries) ​ Layers of Rock – Formed by repeated eruptions over time. ​ Occur when two plates collide, forcing one plate ​ Volcanic Bombs – Large, solid chunks of lava (usually an oceanic plate) beneath another ejected from a volcano. (continental plate) in a process called subduction. ​ The subducted plate melts into magma, which Types of Volcanoes (Based on Activity) rises and forms volcanoes. ​ Example: The Ring of Fire (includes Mt. St. ​ Active – Currently erupting or likely to erupt. (Ex: Helens, Mt. Fuji). Mount Etna, Kilauea) ​ Dormant – Not currently erupting but may in the 2. Divergent Boundaries (Constructive Boundaries) future. (Ex: Mount Rainier) ​ Extinct – No longer capable of erupting. (Ex: ​ Occur when two plates move apart, allowing Shiprock in New Mexico) magma to rise and create new crust. ​ Mostly found at mid-ocean ridges, forming underwater volcanoes that can become islands. ​ Example: Iceland, Mid-Atlantic Ridge. What Determines How Explosive an Eruption Is? ​ Ground swelling or bulging. ​ Increased gas emissions. ​ Gas Content – More trapped gas = more ​ Changes in temperature at the crater. explosive eruption. ​ Viscosity (Thickness) of Magma – Thick magma traps gas, leading to more explosive Types of Volcanic Eruptions eruptions. ​ Silica Content – High silica = high viscosity, ​ Phreatic – Steam-driven explosion, no lava. increasing explosiveness. ​ Phreatomagmatic – Magma and water interact, ​ Water Vapor: more water = bigger explosion causing violent eruptions. ​ Strombolian – Short bursts of lava ejection. ​ Vulcanian – Moderate explosions with thick ash clouds. ** Pyroclastic flow: mixture of gases, water, and ash ​ Plinian – Extremely powerful, creates towering ash clouds. Magma Composition Materials from Volcanic Eruptions That Affect Earth ​ Basaltic Magma – Low silica, very fluid, creates mild eruptions (e.g., Hawaiian volcanoes). ​ Lava Flows – Destroys landscapes but creates ​ Andesitic Magma – Medium silica, creates new land. moderate explosions (e.g., Mt. St. Helens). ​ Ash Clouds – Affects climate and aviation. ​ Granitic (Rhyolitic) Magma – High silica, thick ​ Pyroclastic Flows – Hot gas and rock avalanche, magma, causes violent eruptions (e.g., deadly. Yellowstone). ​ Lahar (Volcanic Mudflow) – Can bury villages. ​ Toxic Gases (SO₂, CO₂, H₂S) – Harmful to life. 3 Types of Volcanoes (Based on Shape) Process of a Volcanic Eruption 1. Shield Volcanoes 1.​ Plate boundaries weaken, allowing magma to ​ Shape: Wide, gently sloping. rise. ​ Eruption Style: Non-explosive, steady lava flows. 2.​ More magma rises, increasing pressure inside ​ Lava Type: Basaltic (low silica, fluid). the magma chamber. ​ Examples: Mauna Loa, Kilauea. 3.​ When pressure becomes too high, it ruptures the crust, causing magma to escape. 2. Composite (Stratovolcanoes) 4.​ Boom! – Eruption occurs, releasing lava, ash, and gases. ​ Shape: Steep-sided, tall. ​ Eruption Style: Explosive, alternating lava and ash layers. 3 Theories on the Cause of Volcanic Eruptions ​ Lava Type: Andesitic (medium silica). ​ Examples: Mount St. Helens, Mount Fuji. 1.​ Tectonic Theory – Eruptions happen due to plate movement. 3. Cinder Cone Volcanoes 2.​ Magmatic Pressure Theory – Rising magma builds pressure until eruption occurs. ​ Shape: Small, steep-sided. 3.​ Gas Expansion Theory – Gas buildup in magma ​ Eruption Style: Short-lived, explosive. chamber leads to explosive eruptions. ​ Lava Type: Basaltic, thick lava. ​ Examples: Paricutin (Mexico). Warning Signs of an Eruption ​ Increased seismic activity. Magma Composition ​ Geothermal Heat Pump – A system that heats or cools buildings by transferring heat between Magma is molten rock beneath the Earth's surface. Its the ground and the building. It works at shallow composition determines the explosiveness of depths and can be used in most locations, not eruptions, the type of volcano formed, and the kind of just volcanic areas. lava produced. The three main types of magma are: 1. Basaltic Magma (Low Silica) Power Plant Steps: How to Generate Electricity 1.​ Wells are drilled deep into the Earth to pump ​ Silica Content: Low (about 45–55%). steam or hot water to the surface ​ Viscosity: Low (very fluid, flows easily). 2.​ When the water reaches the surface, the drop in ​ Gas Content: Low (less explosive eruptions). pressure causes the water to turn into steam ​ Temperature: 1000–1200°C (hottest type). 3.​ The steam spins a turbine, which is connected to ​ Eruption Style: Non-explosive, produces lava a generator that powers electricity flows. 4.​ The cooling tower cools the steam and it ​ Example Volcanoes: Shield volcanoes (e.g., condenses back into the water Mauna Loa, Kilauea in Hawaii). 5.​ The cooled water is pumped back into the Earth to begin the process again 2. Andesitic Magma (Intermediate Silica) ​ Silica Content: Medium (55–65%). ​ Viscosity: Medium (thicker than basaltic). ​ Gas Content: Medium (moderately explosive). ​ Temperature: 800–1000°C. ​ Eruption Style: Explosive, often produces pyroclastic flows. ​ Example Volcanoes: Composite volcanoes (e.g., Mount St. Helens, Mount Fuji). 3. Rhyolitic (Granitic) Magma (High Silica) ​ Silica Content: High (65–75%). ​ Viscosity: Very high (sticky, traps gases). ​ Gas Content: High (very explosive eruptions). ​ Temperature: 650–800°C (coolest type). ​ Eruption Style: Highly explosive, produces thick lava domes and ash clouds. ​ Example Volcanoes: Supervolcanoes (e.g., Yellowstone, Taupo). Geothermal Energy Geothermal energy is heat from the Earth’s interior used for electricity generation and heating. It comes from magma, hot rocks, and underground water heated by volcanic activity. ​ Geothermal Power Plant – A facility that generates electricity by using steam from deep underground to turn turbines. It requires high-temperature geothermal sources, usually near volcanic or tectonic activity.