Volcano Notes PDF

# The Power of Volcanoes: Understanding the Earth's Fiery Mountains ## What is a Volcano? - An opening, or rupture in a planet's surface or crust, allowing hot magma, volcanic ash, and gases to escape from below the surface. - Volcanoes are named after Vulcan, the Roman god of fire! ## Volcanism...

# The Power of Volcanoes: Understanding the Earth's Fiery Mountains ## What is a Volcano? - An opening, or rupture in a planet's surface or crust, allowing hot magma, volcanic ash, and gases to escape from below the surface. - Volcanoes are named after Vulcan, the Roman god of fire! ## Volcanism - Refers to the processes and phenomena associated with the movement of magma beneath or onto the Earth's surface. - It encompasses all volcanic activity, including magma formation, its movement through the crust, eruptions, and the creation of volcanic features. ## How Volcanoes are Formed? - Volcanoes are formed when two tectonic plates push together and the magma from the mantle reaches the surface. - This process can occur at oceanic-continental plate boundaries, where the denser oceanic plate is subducted beneath the continental plate causing the molten rock to well up and erupt from volcanoes. ## Formation of a Volcano: 1. **A crack beneath the Earth's crust extends to the surface and widens.** 2. **A billowing cloud of smoke escapes out of a small hole called a vent.** 3. **Hot molten rock spewing out of the vent. This phenomenon is usually accompanied by ground shaking.** 4. **The moving molten rock, magma, reaches the Earth’s surface and flows out as lava.** 5. **The lava cools, becomes solid, and accumulates in the surrounding area.** 6. **A low-elevated landform called cone develops.** 7. **A mounting structure forms around the cone.** 8. **The accumulating molten rocks may rise hundreds of meters above the ground. Then a volcano was born.** ## Main Parts of a Volcano **Magma Chamber:** - This large underground reservoir of molten rock (magma) is located beneath the volcano. - It serves as the source of lava during an eruption. - When the pressure in the magma chamber builds up, it forces magma toward the surface. **Vent:** - An opening in the Earth's crust through which magma, gases, and volcanic ash are expelled during an eruption. - **Main Vent:** The primary channel through which magma reaches the surface. - **Secondary Vent:** Smaller openings on the sides of a volcano, through which some lava and gases may also escape. **Crater:** - A bowl-shaped depression located at the top of a volcano, around the main vent. - It forms due to explosive eruptions that blow off the top of the volcano or from the collapse of the summit **Caldera:** - A large, more significant depression that forms when a volcano collapses into itself after an explosive eruption. - They are much larger than craters and are often formed when the magma chamber empties and can no longer support the weight above it. **Ash Cloud:** - A large cloud of volcanic ash and gases released into the atmosphere during an explosive eruption. - Volcanic ash is made up of tiny, sharp rock particles and can travel great distances. **Conduit (Pipe):** - The tube-like passage that connects the magma chamber to the surface. - During an eruption, magma travels up this passage and exits through the vent. **Parasitic Cone:** - A smaller cone that forms on the side of a larger volcano, where secondary vents release magma. **Fumaroles:** - These are openings near the vent through which volcanic gases like steam, carbon dioxide, and sulfur dioxide escape. **Volcanic Bombs:** - These are large fragments of lava ejected during an eruption that solidify in the air before falling back to the ground. **Tephra:** - This is a general term for all the volcanic debris, including ash, pumice, and volcanic bombs, that is ejected during an eruption. **Sill:** - A flat piece of rock formed when magma hardens in a crack in the volcano. **Flank:** - The side of the volcano. **Lava Flow:** - This is the movement of molten rock that pours out of a volcano during an eruption. - Lava flows can extend for many kilometers and may destroy anything in their path. ## Main Parts of a Volcano: Lava - A molten rock that breaks through the Earth's surface or through an eruption. - Its temperatures usually at 700 to 1,200 °C. - Bright Yellow over 1000 °C - Orange (800-900 °C) - Dull Red colors (600-700 °C) **Types of Lava: Pahoehoe:** - Lava flows slowly like wax. - It is also known as ropy lava and it has several more varieties named. - A smooth and continuous lava crust. - Only low-viscosity lava can form pahoehoe. - Special conditions are needed for pahoehoe to form: - Low viscosity - Low effusion rate - Gentle slope **Types of Lava: A'A** - Pours out quickly and forms a bitter crust which is torn into jagged, pieces as molten lava flows beneath it. - A roughly rubbly crust of a lava flow. - Walking on it is very slow and potentially dangerous even if one has good hiking boot. - The upper part of A'A lava is composed of loose unstable blocks. **Types of Lava: Blocky Lava:** - Common if the silica content of lava is higher. - They have irregular surfaces but they contain larger lava blocks with smoother sides and angular edges. **Types of Lava: Pillow Lava:** - A type of lava that is always associated with water. - Form when a lava flows out of the Earth's crust underwater. - Usually demonstrate a convex upper and concave or flat lower surface. - The surfaces of pillow lava are glassy. ## Classification of Volcanoes by Activity: - **Active Volcano:** Erupts regularly. The eruption is usually quiet but sometimes becomes violent. - **Dormant Volcano:** Also called a "sleeping volcano," dormant volcanoes have not erupted in a long time but are expected to erupt again in the future. - **Extinct Volcano:** One that is not erupting and is not likely to erupt in the future. ## Types of Volcanic Eruptions: - **Plinian Eruption:** Eruptions with a high rate of magma discharge, sustained for minutes to hours. They form a tall, convective eruption column of a mixture of gas and rock particles, and can cause wide dispersion of ash. - **Pelean Eruption:** Characterized by the formation of domes around the vents and ash flows (pyroclastic flows). - **Vulcanian Eruption:** Includes small to moderate explosive eruptions, lasting seconds to minutes. Ash columns can be up to 20 km in height, and lava blocks and bombs may be ejected from vent. - **Strombolian Eruption:** Named after a volcano on the Lipari Islands in the Mediterranean. Have explosions causing a shower of lava fragments. - **Hawaiian Eruption:** The least violent type of eruption where extremely fluid lava flows quietly from rift or fractures and gradually forms a large, smoothly sloping shield volcano. Hawaiian eruptions have fire fountains and lava flows. ## Types and Characteristics of a Volcano: - **According to Their Structure:** - **Cinder Cone Volcano (Scoria Volcano):** A smaller, steep-sided hill made of volcanic debris like ash, lava fragments, and cinders. - **Shield Volcano:** Formed when fluid magma erupts quietly and flows from a vent to gradually build up low, broad mountains with gentle slopes. - **Composite (Strato) Volcano:** Their eruptions are dangerous and explosive in nature, with many layers of lava and pyroclastic materials. - **Lava Dome Volcano:** Forms when thick, extremely viscous lava erupts, hardening in a dome shape. - **According to Their Activity:** - Active - Dormant - Extinct - **According to Their Eruption:** - Plinian - Pelean - Vulcanian - Strombolian - Hawaiian ## World's Most Threatening Volcanoes: - **Campi Flegrei Caldera - Italy:** This dangerous volcano is located in West of Naples, Italy. It shook with gigantic explosive eruptions about 35,000 and 12,000 yrs. ago. - **Mount Rainier - United States:** The main hazard from an eruption would be the creation of lahars (landslides or mudflows of volcanic debris that resemble wet concrete). An eruption would probably melt the glaciers capping the mountain, causing flash floods that would mix with loose volcanic ash and other rock debris. - **Fuji Volcano - Japan:** After a dormancy of 300 yrs., Fuji may be coming back to life, judging from a large number of earthquakes that started in October 2000. - **Mount Vesuvius - Italy:** About 3 million people live near the volcano, so even the smallest eruption is almost certain to have a large impact. - **Santorini Caldera - Greece:** In about 1640 BC a gigantic eruption occurred on the eastern Mediterranean island of Thera, also known as Santorini. The eruption was so destructive that it was probably a factor in the decline of the Minoa culture . - **Reykjanes Peninsula - Iceland:** The submarine mid-ocean ridges form Earth's longest and most active volcanic zones. - **Long Valley Caldera - United States:** This enormous volcano in east central California has been in a state of unrest since , with earthquakes along the boundary of the caldera, periodic uplift of the caldera floor, and increased emission of gases. - **Rabaul Caldera - Papua New Guinea:** The volcanic activity has continued at a low level to the present day. - **Krakatoa Volcano - Indonesia:** More than half of Krakatoa Island disintegrated during an explosive eruption. The entrance pf pyroclastic flows into the sea during the eruption caused huge tsunamis to strike the neighboring islands of Java and Sumatra, killing about 34,000 people. - **Paektu-san (Baitou Shan) - China-North Korea:** A colossal volcanic eruption occurred on the present-day border of China and North Korea. The explosion formed a caldera now filled by Lake Chon-ji (Tian Chi). - **Taupo (Volcano) - New Zealand:** This volcano had a violent eruption in AD 186 that blew apart and created a huge hole in the ground to form Lake Taupo. ## Where are Volcanoes Mostly Found? - 60% of all active volcanoes occur at the boundaries between tectonic plates. - Most volcanoes are found along a belt "Ring of Fire" that encircles the Pacific Ocean. - **Philippines:** There are more or less 53 volcanoes in the Philippines. Five of these volcanoes are found in North of Luzon. - Iraya - Babuyan Claro - Didicas - Camiguin de Babuyanes - And unnamed volcano - **Luzon Island:** There are 25 in the Luzon Island. - **Central Philippines:** There are 8 volcanoes are found in Central Philippines. - **Mindanao:** There are 13 volcanoes found in Mindanao. ## Before, During, and After a Volcanic Eruption: - It is the task of the CS - Philippine Institute of Volcanology and Seismology to advise us on the possible dangers of volcanic eruption. **Before a Volcanic Eruption:** 1. Prepare a disaster supply kit, which includes the following: flashlight, battery-operated radio, food, water, goggles, and disposable breathing masks. 2. Stay away from active volcano sites. 3. If you live near a known volcano, active or dormant, learn about your community warning systems and emergency plans and be ready to evacuate when told to do so. 4. Have an emergency disaster plan for you and your family. 5. Be prepared for the hazards that can accompany volcanic eruptions such as mudflows and flashfloods, landslides and rockfalls, earthquakes, ashfalls, acid rain, and tsunamis. **During a Volcanic Eruption:** 1. Listen to radio or television for the latest emergency information. 2. Follow the evacuation order issued by authorities. 3. Avoid the areas and river valleys downstream of the volcano. 4. If caught indoors: - Close all windows and doors. - Bring animals and livestock into closed shelters. 5. If trapped outdoors, seek shelter indoors. 6. If caught in a rockfall, roll into a ball to protect your head. 7. If caught near a steam, be aware of mudflows, and move up to higher grounds especially if you hear the roar of a mudflow. 8. To protect yourself during ashfall: - Wear long-sleeved shirts and long pants. - Use goggles to protect your eyes. - Use a dust mask or hold a damp cloth over your face to help breathing. - Keep truck or engines off. 9. Most importantly, stay out of the area defined as a restricted zone by the government officials. **After a Volcanic Eruption** 1. If possible, stay away from volcanic ashfall areas. 2. When outside: - Cover your mouth and nose. Volcanic ash can irritate your respiratory system. - Wear goggles to protect your eyes. - Keep skin covered to avoid irritation from contact with ash. 3. Clear roofs of ashfall. Ashfall is very heavy and can cause buildings to collapse. Be careful when working on a roof. 4. Avoid driving in heavy ashfall. This can stir up more ash and can clog engines. 5. If you have a respiratory ailment, avoid contact with any amount of ash. Stay indoors until health officials declare it is safe to go outside. 6. Remember to help your neighbors who may require special assistance - infants, elderly, and people with disabilities.