Volcanoes Notes PDF

VOLCANOES OBJECTIVES Describe a volcano. Discuss the different parts and features of a volcano. Differentiate active and inactive volcanoes. Discuss the different types of volcano. How Volcanoes Form The movement of faults at plate boundaries can provide a convenient pathway for magm...

VOLCANOES OBJECTIVES Describe a volcano. Discuss the different parts and features of a volcano. Differentiate active and inactive volcanoes. Discuss the different types of volcano. How Volcanoes Form The movement of faults at plate boundaries can provide a convenient pathway for magma to reach the surface. constructive boundaries (divergent): where plates are moving away from each other as new crust is created between the two plates destructive boundaries (convergent): where plates are moving towards each other and old crust is either dragged down into the mantle at a subduction zone or pushed upwards to form mountain ranges How Volcanoes Form Volcanoes can also form above a column of superheated magma called a mantle plume. This may happen in areas that are distant from plate boundaries. It is also referred to as hot spot or intraplate volcanism. Heat from the mantle plume causes melting and thinning of the crust, which leads to volcanic activity at the surface. The Hawai’ian Islands are a chain of volcanoes in the middle of the Pacific Plate, which have formed due to the presence of a hot spot. Over millions of years, the Pacific Plate has moved over the hot spot, creating a chain of volcanic islands. The distribution of volcanoes around the world mostly lie on plate boundaries, in particular a region a called the Pacific Ring of Fire around the edge of the Pacific Plate. What are the parts of a volcano? Magma - Molten rock beneath Earth's surface. Parasitic Cone - A small cone-shaped volcano formed by an accumulation of volcanic debris. Sill - A flat piece of rock formed when magma hardens in a crack in a volcano. Vent - An opening in Earth's surface through which volcanic materials escape. Flank - The side of a volcano. Lava - Molten rock that erupts from a volcano that solidifies as it cools. Crater - Mouth of a volcano - surrounds a volcanic vent. Conduit - An underground passage magma travels through. Summit - Highest point; apex Throat - Entrance of a volcano. The part of the conduit that ejects lava and volcanic ash. Ash - Fragments of lava or rock smaller than 2 mm in size that is blasted into the air by volcanic explosions. Ash Cloud - A cloud of ash formed by volcanic explosions. Craters and Calderas Many volcanoes contain a depression. Small depressions (i.e. less than 1 km across) are called craters whereas those over 1 km across are called calderas. Most craters result from the explosive activity by which the volcanic vent is cleared. However, most calderas result from subsidence produced by the removal of large volumes of the underlying magma. Many present-day craters and calderas are filled with water, and are know as crater lakes. The Philippine Institute of Volcanology and Seismology (PHIVOLCS) classifies volcanoes according to their eruptive history. Active Volcanoes-erupted within historical times (within the last 600 years), accounts of these eruptions were documented by man erupted within the last 10,000 years based on the analyses of material from young volcanic deposits. Inactive Volcanoes-no recorded eruptions, physical form has been intensively weathered and eroded, bearing deep and long gullies. Inactive Volcanoes Inactive volcanoes can be further classified as dormant and extinct. Dormant volcanoes have not erupted for a very long time but may erupt at a future time. Extinct volcanoes are not expected to erupt in the future. What causes volcanoes to erupt? When enough magma builds up in the magma chamber, it forces its way up to the surface and erupts, often causing volcanic eruptions. In the ocean, volcanoes erupt along cracks that are opened in the ocean floor by the spreading of two plates called a mid-ocean ridge. Name of Volcano Province Babuyan Claro Babuyan Island Group, Cagayan in Luzon Boundaries of Laguna and Quezon in Banahaw Luzon Biliran (Anas) Leyte in Visayas Bud Dajo Sulu in Mindanao Bulusan Sorsogon, Bicol Region in Luzon Cabalian Southern Leyte in Visayas Cagua Cagayan in Luzon Camiguin de Babuyanes Babuyan Island Group, Cagayan in Luzon Didicas Babuyan Island Group, Cagayan in Luzon Hibok-hibok Camiguin in Mindanao Name of Volcano Province Iraya Batan Island, Batanes in Luzon Iriga Camarines Sur in Luzon Isarog Camarines Sur in Luzon Kanlaon Negros Oriental Leonard Kniaseff Davao del Norte Makaturing Lanao del Sur Matutum Cotobato in Mindanao Mayon Albay, Bicol Region in Luzon Musuan (Calayo) Bukidnon in Mindanao Name of Volcano Province Parker South Cotobato/General Santos Boundaries of Pampanga, Tarlac and Pinatubo Zambales in Luzon Lanao del Sur and Cotobato in Ragang Mindanao Babuyan Island Group, Cagayan in Smith Luzon Taal Batangas in Luzon OBJECTIVES Discuss the different types of a volcano. Explain how volcanoes erupt. Provide some signs of an impending volcanic eruption. Discuss the factors affecting the explosiveness of volcanoes. Describe each type of volcanic eruption. Lava domes are formed by viscous magma being erupted effusively onto the surface and then piling up around the vent. USGS picture of the growing Mount St. Helens Lava dome. This lava dome started developing shortly after the iconic May, 18th 1980 eruption and dome growth continued until 1986. Photo credit: USGS. 1984 Mt. Amorong in Pangasinan Lava Dome Volcano Shield Volcano Cinder Cone Volcano Mayon Volcano in Albay Composite Volcano Why do volcanoes erupt? 1. When enough magma builds up in the magma chamber, it forces its way up to the surface and erupts. 2. In the ocean, volcanoes erupt along cracks that are opened in the ocean floor by the spreading of two plates called a mid-ocean ridge. SIGNS OF AN IMPENDING VOLCANIC ERUPTIONS SIGNS OF AN IMPENDING VOLCANIC ERUPTIONS SIGNS OF AN IMPENDING VOLCANIC ERUPTIONS What are the importance of observing the various signs of an impending volcanic eruption? OBJECTIVES Discuss the different types of a volcano. Explain how volcanoes erupt. Provide some signs of an impending volcanic eruption. Discuss the factors affecting the explosiveness of volcanoes. Describe each type of volcanic eruption.  OBJECTIVES Identify various tools and technologies used in monitoring volcanoes. Explain how data from these parameters and tools help predict volcanic eruptions and mitigate volcanic hazards. Identify and describe different types of volcanic hazards. Different Parameters Assessed in a Volcano’s Status Electronic Distance Meter (EDM) Different Parameters Assessed in a Volcano’s Status Global Positioning System (GPS) Different Parameters Assessed in a Volcano’s Status Different Parameters Assessed in a Volcano’s Status Different Parameters Assessed in a Volcano’s Status Seismometer Volcanic Hazards LAVA FLOW Lava flows are rivers of incandescent of molten rock or lava moving downslope or away from an eruption vent. Lava flows composed of low silica magma have low viscosities and tend to flow at high speeds (kilometers per hour) Volcanic Hazards TEPHRA (ASHFALL) Tephra (fragmented volcanic particles) or ash (fragmented volcanic particles less than 2 mm in diameter) propelled through the atmosphere in an eruption plume or an eruption column eventually fall or gravitationally settle over areas downwind of an erupting volcano, forming blankets of tephra fall or ashfall.  Volcanic Hazards PYROCLASTIC DENSITY CURRENTS or PDCs PDCs are mixtures of fragmented volcanic particles (pyroclastic), hot gases and ash that rush down the volcanic slopes or rapidly outward from a source vent at high speeds.  Volcanic Hazards LATERAL BLASTS Lateral blasts are laterally-directed thrusts of hot gas and ash that can be generated from an exploding dome on the summit vent or inside the edifice when sudden mass failure of the volcanic flanks occur.  Volcanic Hazards VOLCANIC GAS Volcanic gases form a dissolved component of magma that is released to the atmosphere in large quantities during eruptions. The principal volcanic gases are water vapor, hydrogen sulfide, sulfur dioxide, carbon dioxide, carbon monoxide, hydrogen chloride and hydrogen fluoride.  Volcanic Hazards LAHAR Lahars (an Indonesian term), sometimes called volcanic mudflows or debris flows, are slurries of volcanic sediment, debris and water that cascade down a volcano’s slopes through rivers and channels. Volcanic Hazards DEBRIS AVALANCHE (SECTOR COLLAPSE) Debris avalanche or sector collapse is the mass failure of the flanks of a volcano edifice due to magma intrusion, a strong earthquake or the movements of faults beneath the edifice. Volcanic Hazards GROUND SUBSIDENCE and FISSURING Ascending magma can cause the ground to break up into fissures, typically along weaknesses in the rock such as fractures or faults. After magma has been erupted, its removal from the subsurface can cause the ground to sink and subside and further fissuring to occur. Ground subsidence and fissuring are typically accompanied by earthquakes. https://coloradogeologicalsurvey.org/hazards/ground- subsidence/ Volcanic Hazards SECONDARY EXPLOSIONS, PDCs and ASHFALL Secondary explosions can be generated in still hot volcanic deposits such as those of PDCs and lava flow when these come into contact with water by erosion, rising groundwater or rainfall. These can cause remobilization of volcanic material to generate small-scale PDCs and minor ashfall. https://australian.museum/learn/minerals/shaping-earth/how-are- volcanoes-and-earthquakes-interrelated/ What factors affect volcanic eruption? 1. Viscosity – the measure of fluid’s resistance to flow 2. Gas content 3. Magma composition – silica content Types of Volcanic Eruption Icelandic- volcanic eruptions that flood the surface of the Earth with massive amounts of very hot, very thin, runny lava. Hawaiian eruptions are similar to Icelandic eruptions. The main difference lies in the fact that most Hawaiian eruptions have the greatest quantity of lava pouring out of the main vent at the volcano's summit, not along side fissures. Strombolian eruptions are short lived explosive eruptions that shoot very thick and pasty lava into the air along with bursts of steam and gas. Vulcanian eruptions are more violent and explosive than strombolian eruptions. Vulcanian eruptions contain high dark clouds of steam, ash, and gas. Pelean and Plinian eruptions are the most dangerous and explosive of the eruption types. Pelean eruption is associated with explosive outbursts that generate pyroclastic flows, dense mixtures of hot volcanic fragments and gas A Plinian eruption is the most explosive of the eruption types. Objective: Make precautionary measures before, during, and after a volcanic eruption. How to prepare Develop an evacuation plan and a sheltering plan for yourself, your family, and others in your household. Review the plans and make sure that everyone understands them. Prepare the necessary things. What to prepare Flashlight and extra batteries First aid kit and manual Emergency food and water Manual (nonelectric) can opener Essential medicines Sturdy shoes Respiratory (breathing) protection Eye protection (goggles) Battery-powered radio Preparing to evacuate Follow authorities’ instructions if they tell you to leave the area. Tune in to the radio or television for volcano updates. Listen for disaster sirens and warning signals. Review your emergency plan and gather your emergency supplies. Be sure to pack at least a 1-week supply of prescription medications. Prepare an emergency kit for your vehicle with food, flares, booster cables, maps, tools, a first aid kit, a fire extinguisher, sleeping bags, a flashlight, batteries, etc. Fill your vehicle’s gas tank. Preparing to evacuate If no vehicle is available, make arrangements with friends Place vehicles under cover, if at all possible. Put livestock in an enclosed area. Plan ahead to take pets with you. Fill your clean water containers. Fill sinks and bathtubs with water as an extra supply for washing. Adjust the thermostat on refrigerators and freezers to the coolest possible temperature. If the power goes out, food will stay cooler longer. During Volcanic Eruption Stay indoors as much as possible. Keep doors and windows closed. Use damp curtains, blankets, or clothing to prevent infiltration of ash into the house. Use dust masks. Wear goggles or eyeglasses to protect eyes from irritation. Listen to the radio announcement. Follow instructions of authorities. After the Eruption Stay away from ashfall areas, if possible. Avoid contact with ash as much as you can. Keep your skin covered to avoid irritation from contact with ash. Wear goggles to protect your eyes from ash. Do not travel unless you have to. Driving will stir up more ash that can clog engines and stall vehicles. Clear roofs of ash. Ash is very heavy and can cause buildings to collapse. Be very cautious when working on a roof. Ash can be slippery and make it easy to fall. Use another source of drinking water, such as purchased bottled water, until your water can be tested. What are the positive effects of volcanoes and volcanic eruptions? 1.Geothermal power plants - the heat from deep inside the Earth is used to produce steam to generate electricity 2. Geothermal heat pumps- use the heat coming from close to the Earth’s surface to heat water or provide heat for buildings  232.5-MW Malitbog (Leyte) 180-MW Mahanagdong (Leyte) 125-MW Upper Mahiao (Leyte) 123.0-MW Tongonan (Leyte) GEOTHERMAL 50.9-MW Optimization (Leyte) POWER 120-MW Bacman I (Bicol) PLANTS IN THE 20-MW Bacman II (Bicol) 112.5-MW Palinpinon I (Negros Island) PHILIPPINES 60-MW Palinpinon II (Negros Island) 49.4-MW Nasulo (Negros Island) 52-MW Mindanao I (North Cotabato) 54-MW Mindanao II (North Cotabato) Tongonon Leyte Geothermal Power Plant The following steps are followed to generate electricity in a geothermal power plant. 1. Wells are drilled deep into the earth to pump steam or hot water to the surface. 2. When the water reaches the surface, the drop in pressure causes the water to turn into steam. 3. The steam spins a turbine, which is connected to a generator that produces electricity. 4. Cooling tower cools the steam which condenses back into water. 5. The cooled water is pumped back into the earth to begin the process again. Other positive effects: a. It can create spectacular scenery. b. It can produce rich soil for farming. c. It can cause a decrease in the Earth’s surface temperature. e. People became creative by making earthenware out of the ashfall. Negative effects: a. Cause loss of lives. b. Damage properties. c. Cause air pollution d. Cause water pollution OBJECTIVES Identify the different volcanic alert levels and their corresponding meanings. Explain how monitoring data is used to determine the alert level of a volcano. Discuss the role of volcano alert systems in risk management and disaster preparedness.  TAAL VOLCANO ALERT LEVEL SCHEME As of June 2021 The PHIVOLCS Volcano Alert Level Scheme is a reference guide to understanding the state of an active volcano, the current level of threat it poses and the steps that are needed to be taken to ensure public safety. ALERT LEVEL represents the overall condition of the volcano, with Alert Levels 1 to 5 corresponding to increasing severity of unrest. MONITORING CRITERIA are parameters from instrumental, visual and other sensory observations of the volcano that are primarily acquired by on-site Volcano Observatories and scientific surveys. INTERPRETATION explains the probable processes taking place within the volcano based on monitoring criteria and the potential dangers that may arise from these processes. RECOMMENDATIONS are response measures that must be followed by the public and implemented by local and national government units to ensure that populations are kept out of harm’s way. STEP-DOWN CRITERIA are conditions that need to be met before the Alert Level is brought down to the next level.  TAAL VOLCANO ALERT LEVEL SCHEME As of June 2021 Alert Level Monitoring Step-down Alert Level (Step-up) Criteria Interpretation Recommendations Criteria (Step-down) Background Quiescence; no Permanent habitation 0 parameters: major eruption in on Taal Volcano Island NORMAL Volcanic foreseeable future, (TVI) must not be earthquakes but steam-driven allowed. typically 1,000 explosions can to Alert Level 0. LOW-LEVEL tonnes/day, slight occur without UNREST increases in fumarole warning. and/or Main Crater Lake temperatures and acidity; Slight and/or localized inflationary ground deformation changes in TVI.  TAAL VOLCANO ALERT LEVEL SCHEME As of June 2021 Alert Level Recommenda Step-down Alert Level (Step-up) Monitoring Criteria Interpretation tions Criteria (Step-down) Increasing changes in Shallow Entry into TVI Alert Level 2 2 parameters: Elevated level of hydrothermal unrest must not be monitoring DECREASED seismic activity with some felt and/or deep-seated allowed. criteria have UNREST events in TVI and Taal Caldera magmatic intrusion Communities in been in decline (TC); Occurrence of earthquake may be occurring, pre-defined for one (1) swarms and low-frequency bringing higher areas of the month before 2 events; Sustained increases in chances of steam- highest hazard lowering to INCREASING inflationary ground deformation driven, gas or must ready for Alert Level 1. UNREST including ground tilt in TVI; Slight hydrothermal possible positive microgravity changes in explosions. evacuation. TVI and TC; Increasing fumarole temperature and acidity and upwelling in the Main Crater Lake; Significant increases in CO2 emission, instrumental detection of airborne SO2 >500 tonnes/day.  TAAL VOLCANO ALERT LEVEL SCHEME As of June 2021 Alert Level Recommend Step-down Alert Level (Step-up) Monitoring Criteria Interpretation ations Criteria (Step-down) 3 Intensifying changes in Magmatic or TVI, Taal Lake Alert Level 3 3 INTENSIFIED parameters: Sudden increase explosive and pre- monitoring DECREASED UNREST/ or decline in seismic activity; phreatomagmatic defined criteria have TENDENCY MAGMATIC Perceptible earthquakes, eruption is lakeshore been in TOWARDS UNREST occurrence of swarms of imminent; communities decline for at HAZARDOUS volcano-tectonic and/or hybrid precursory of Batangas least two (2) ERUPTION earthquakes; Elevating SO2 eruptive activity facing the weeks before flux; Significant changes in may be taking active vent lowering to Main Crater Lake temperature place and must be Alert Level 2. and/or acidity; Accelerating generating evacuated. increase in ground inflation, ashfall, ballistics rapid increase in ground tilt in and/or short lava TVI; Precursory phreatic or flows. weak phreatomagmatic eruptions commence.  TAAL VOLCANO ALERT LEVEL SCHEME As of June 2021 Alert Level Recommend Step-down Alert Level (Step-up) Monitoring Criteria Interpretation ations Criteria (Step-down) Accelerating changes or abrupt Strong Communities Alert Level 4 4 decline in parameters: Rapidly phreatomagmatic in pre- monitoring DECREASED intensifying volcanic or magmatic determined criteria have TENDENCY earthquakes, continuous eruption is taking worst-case or been in TOWARDS volcanic tremor, frequent felt place, which may scenario- decline for HIGHLY earthquakes; Profuse degassing or may not lead to based volcanic two (2) weeks HAZARDOUS 4 or ash explosions along existing violently explosive hazards zones before ERUPTION HAZARDOUS or new vents and fissures; eruption. must be lowering to ERUPTION Elevated and/or sudden drop in Widespread ashfall evacuated. Alert Level 3. IMMINENT SO2 flux; Accelerating increase and ballistics, lava or reversal of ground flows and minor deformation patterns and pyroclastic density ground fissuring; Explosive currents (PDCs) on eruption or lava effusion with or TVI may be without volcanic lightning generated. commence.  TAAL VOLCANO ALERT LEVEL SCHEME As of June 2021 Alert Level Recommenda Step-down Alert Level (Step-up) Monitoring Criteria Interpretation tions Criteria (Step-down) 5 Violently explosive magmatic Plinian/ Subplinian/ Additional Alert Level 5 5 HIGHLY eruption ongoing: Continuous Violent areas for conditions HIGHLY HAZARDOUS intense seismic activity, including phreatomagmatic evacuation have ceased HAZARDOUS ERUPTION IN explosion-type volcanic eruption is taking should be for at least ERUPTION IN PROGRESS earthquakes and strong felt place. Extreme life- considered 24 hours PROGRESS events; Sustained tall eruption threatening hazards based on before column with expansive umbrella of base surges/PDCs, prevailing lowering to cloud accompanied by loud volcanic tsunami, conditions. Alert Level 4. booming sounds and volcanic thick tephra lightning; Generation of fall/ashfall, fissuring, PDCs/base surges and volcanic lahars and landslides tsunami that transport across Taal could impact Lake and lakeshore towns; Ground communities around fissuring and large-particle tephra the lake and fall impacting lakeside downwind of the communities and ashfall impacting eruption plume. farther areas. Sources https://www.phivolcs.dost.gov.ph/index.php/volcano-hazard/introduction-to-volcanoes https://www.scribd.com/document/412918641/Signs-of-an-Impending-Volcanic-Eruption-1 https://www.bgs.ac.uk/discovering-geology/earth-hazards/volcanoes/how-volcanoes-form-2/ https://www.phivolcs.dost.gov.ph/index.php/volcano-hazard/volcano-alert-level