Volcanoes and Earthquakes

• Volcanoes are openings in the Earth's crust where magma, gases, and ash erupt onto the surface.
• Volcanoes form as a result of tectonic activity, including subduction, rifting, and hot spots.
• Volcanoes are found worldwide and vary in shape and size.
• Active volcanoes erupt frequently, while dormant volcanoes haven't erupted in many years but could erupt again.
• Extinct volcanoes have not erupted in many years and are not expected to.
• A volcanic eruption can be dangerous, producing lava flows, ash clouds, and pyroclastic flows.

Parts of a Volcano

• Crater: A bowl-shaped depression at the top that forms when the summit collapses after an eruption.
• Magma Chamber: A large underground cavity where molten rock (magma) is stored before eruption.
• Conduit: A narrow channel connecting the magma chamber to the surface, through which magma rises.
• Fumarole: A vent on the surface that emits steam, gas, and other volcanic gases, usually near the summit.

Location of Volcanoes

• The Ring of Fire is a horseshoe-shaped region in the Pacific Ocean that is home to many active volcanoes.
• The Ring of Fire stretches from South America (Chile) to North America (Alaska) to Japan to The Philippines to New Zealand.
• The Ring of Fire contains 75% of the Earth's volcanoes and 90% of its earthquakes due to intense tectonic plate movement.
• Subduction Zones: Oceanic plates (thinner, denser) are forced under continental plates (thicker, lighter).
• Oceanic plates melt as they sink due to high temperatures and pressure, forming magma that creates volcanoes.
• Andes Mountains (Chile, South America) is an example of this phenomenon.
• Rift Zones: Tectonic plates move away from each other, allowing magma to rise and form volcanoes.
• This occurs along continental rifts and mid-ocean ridges.
• The East African Rift (Mount Nyiragongo in the Democratic Republic of the Congo) is an example of this phenomenon.
• Hot Spots: Fixed areas deep in the Earth where hot magma rises through the crust and creates volcanoes.
• Hot spots remain in the same place, but as tectonic plates move over them, chains of volcanoes form over time.
• The Hawaiian Islands were formed by a hot spot in the middle of the Pacific Plate.
• The Mauna Loa and Kilauea volcanoes are a result of this.
• Mid-Ocean Ridges: The ocean floor spreads at divergent boundaries, causing plates to pull apart.
• Magma rises to fill the gap when the plates separate, creating new oceanic crust and volcanoes, forming underwater mountain chains over time.
• The Mid-Atlantic Ridge is an example of this phenomenon.
• It runs through the Atlantic Ocean.
• The North American and Eurasian Plates are moving apart here, widening the Atlantic Ocean.
• Most volcanoes are found along the edges of tectonic plates (plate boundaries).
• Plate boundaries create different types of volcanic activity.

Types of Volcanic Activity

• Active: Currently erupting, has erupted recently, or shows signs of erupting in the near future.
• Dormant: Has not erupted in a long time (hundreds or thousands of years) but still has the potential to erupt again.
• Extinct: Has not erupted for thousands or millions of years and is no longer connected to a magma source.

Active Volcanoes

• They have a direct connection to a magma source.
• Active volcanoes often release steam, ash, and gases (like sulfur dioxide), or lava even when not fully erupting.
• Examples: Mount Etna (Italy), Kilauea (Hawaii, USA), Taal Volcano (Philippines).
• Signs: Increased earthquakes around, Changes in gas emissions (especially sulfur dioxide), bulging or swelling, and sudden temperature changes in nearby hot springs or crater lakes.

Dormant Volcanoes

• Dormant volcanoes still have a magma source, but it is currently inactive.
• Scientists carefully monitor dormant volcanoes.
• Examples: Mount Rainier (USA), Mount Fuji (Japan), Mount Pinatubo (Philippines).
• Dormant volcanoes can be dangerous because people often build homes and cities near them, and they can suddenly wake up and erupt without warning.
• Mount Vesuvius (Italy) was dormant before erupting in 79 AD, burying Pompeii and Herculaneum.

Extinct Volcanoes

• The magma chamber beneath the volcano has cooled and solidified, preventing future eruptions.
• Extinct volcanoes have eroded over time, losing their original shape.
• Examples: Mount Kilimanjaro (Tanzania), Edinburgh Castle Rock (Scotland), Shiprock (USA).
• Volcanoes become extinct if a tectonic plate moves away from a hot spot, cutting off the magma supply, the magma chamber cools, or erosion and weathering occurs over time.

Types of Volcanoes

• Shield Volcanoes: Broad, gently sloping cone shape, formed by numerous lava flows spreading from a central vent.
• Shield Volcanoes eruptions are typically Non-explosive with thin, runny lava that flows for long distances
• Examples: Mauna Loa and Kilauea in Hawaii.
• Stratovolcanoes: Tall, steep-sided volcanoes with a classic, cone-shaped appearance, formed by alternating layers of lava, ash, and volcanic debris.
• Stratovolcanoes can have explosive or non-explosive eruptions.
• They are known for their powerful explosions and pyroclastic flows.
• Examples: Mount Fuji in Japan and Mount St. Helens in the U.S.
• Cinder Cones: Small, steep-sided volcanoes made of loose, pyroclastic material such as ash, cinders, and volcanic bombs.
• Cinder Cones are mostly formed by Explosive eruptions from a single vent.
• Mauna Kea in Hawaii and Mount Etna in Italy are examples.

Types of Volcanic Eruptions

• Volcanic eruptions occur when magma rises through a vent in the Earth's crust.
• Eruptions are classified based on magma type, gas amount, and eruption style.
• Vulcanian Eruptions: More explosive than Hawaiian and Strombolian eruptions, characterized by the ejection of large amounts of ash, gas, and rock fragments.
• The eruption column can reach several kilometers high, and the ash can travel long distances in Vulcanian Eruptions.
• Plinian Eruptions: Most explosive type of volcanic eruption, characterized by the eruption of large amounts of ash, gas, and pumice, forming a mushroom-shaped cloud that can rise several tens of kilometers.
• Pelean Eruptions: The volcanic vent can become blocked by viscous magma, causing a build-up of pressure that is released in a violent explosion.
• The resulting pyroclastic flow can move at extremely high speeds, reaching hundreds of kilometers per hour.
• Strombolian Eruptions: Characterized by frequent, small explosions that eject cinders, ash, and blobs of molten lava, caused by gas bubbles in the magma bursting at the surface.
• Hawaiian Eruptions: Characterized by the effusive eruption of basaltic lava that flows out and spreads over a large form shield volcanoes.
• Hawaiian Eruptions tend to be non-explosive with lava flows steadily and relatively slowly.
• Icelandic Eruptions: Typically non-explosive and relatively gentle with lava flowing out of fissures or vents, covering large distances and creating lava fields and shield volcanoes.
• Surtseyan Eruptions: Characterized by the interaction between magma and water, leading to explosive eruptions that create a mixture of steam, ash, and rock fragments, also resulting to a steam-filled cavity.

Effect of Volcanic Eruptions

• Property Damage can be caused by lava flows, pyroclastic flows, or lahars (mudflows), which can destroy buildings, infrastructure, and agricultural land.
• Water Pollution can be caused when ash and other materials are released into bodies of water, killing aquatic life, & contaminate drinking water supplies.
• Air Pollution can be caused when large amounts of gasses such as sulfur dioxide and carbon dioxide are released into the atmosphere, which can react with other compounds and lead to the formation of acid rain and smog.
• Health Hazards can be caused when the ash and other particles released can Harmful to human health if inhaled, causing respiratory problems and aggravate existing health conditions.
• Soil Fertility: Volcanic ash is rich in minerals & provide nutrient-rich soil, producing productive agricultural land.
• Geothermal Energy can be produced by activity & Harnessed for electricity generation/heating; providing clean/sustainable energy source.
• Positive Effects can includes new landforms such as new habitats for plants and animals, and support new ecosystems.
• The tourism spots such as hot springs, geysers, and lava fields can become tourist attractions, which brings economic benefits to local communities.

Explore the world of volcanoes, earthquakes, and plate tectonics. Learn about volcanic features, magma formation, subduction zones, and the Ring of Fire. Test your knowledge with these questions.