Science Reviewer: Volcanoes PDF

Introduction to Volcanoes: A volcano is described as an opening in the Earth's crust, allowing magma, ash, and gasses to escape. The term "volcano" is rooted in Latin (from “vulcan”) They thought it was an entrance to the fiery underworld Formation of Volcanoes Magma, located 50-...

Introduction to Volcanoes: A volcano is described as an opening in the Earth's crust, allowing magma, ash, and gasses to escape. The term "volcano" is rooted in Latin (from “vulcan”) They thought it was an entrance to the fiery underworld Formation of Volcanoes Magma, located 50-100 miles below the Earth’s surface, begins to rise due to its lower density compared to surrounding rocks. As magma rises, it melts gaps in the surrounding rock, forming pathways. A large magma reservoir or chamber forms 2 miles below the Earth's surface. Pressure from the surrounding rock causes the magma to forcefully melt or blast a conduit (channel) through which it reaches the surface. Magma erupts through a vent on the Earth’s surface, after which it is referred to as lava. The accumulation of lava at the vent eventually builds up, forming a volcano. Anatomy of a Volcano Crater: A bowl-shaped depression formed by volcanic activity, an explosion, or the impact of a meteorite. Cone: The external structure built from the accumulation of lava and/or tephra. Caldera: A large crater formed when a volcano’s cone collapses into the emptied magma chamber. Conduit: The channel that magma travels through from the magma chamber to the surface. Magma Chamber: The underground reservoir where magma collects before an eruption. Lava: Molten rock that emerges onto the surface during an eruption.  Parasitic Cone: A secondary, smaller cone that forms on the side of the main volcano, sharing the same magma conduit. Fumarole: A secondary vent that emits only gasses, without lava. Fissure: A long crack through which lava flows to the surface. Vent: The opening at the surface through which volcanic materials like lava, ash, and gasses are expelled. The Ring of Fire The Ring of Fire contains 90% of the world’s volcanoes, both active and dormant. It circles the Pacific Ocean, encompassing parts of South America, North America, Asia, and Australasia. Types of Volcanoes Shield Volcanoes ○ Shield volcanoes are broad, dome-shaped formations built from hardened lava flows. ○ They are named after their shape, which resembles a warrior's shield. ○ These volcanoes have a large base with gentle slopes and can grow several miles high. ○ Their lava is hot, thin, and very fluid, often basaltic in nature. ○ Examples: The Hawaiian Islands and Iceland. On Mars, Olympus Mons is the largest shield volcano. ○ Trivia: Mauna Loa in Hawaii is the largest volcano on Earth and exemplifies the broad, expansive nature of shield volcanoes. Cinder Cone Volcanoes ○ Cinder cone volcanoes are smaller, cone-shaped volcanoes built from hardened magma and gravel-sized lava rock fragments called cinders. ○ They have a small base, are steep-sided, and can grow up to 1,000 feet tall.  ○ They typically have a short lifespan of a few years and are known for violent eruptions. ○ Lava from cinder cone volcanoes tends to stick rather than flow, creating steep cones. ○ Examples: Smith Volcano on Babuyan Island and Taal Volcano in the Philippines. Composite Volcanoes (Stratovolcanoes) ○ Composite volcanoes are formed by alternating layers of lava and tephra (airborne volcanic material). ○ These volcanoes are often snow-capped and can remain dormant for long periods, giving the impression of extinction. ○ They are typically found in subduction zones and have violent eruptions. ○ The eruptions alternate between tephra and lava, which builds up both the height and base of the volcano. ○ Examples: Mt. Rainier, Mt. Fuji, and Mt. Kilimanjaro. Other Types of Volcanoes Supervolcano ○ A supervolcano is characterized by an enormous caldera and can produce catastrophic eruptions on a continental scale. ○ Eruptions from supervolcanoes are capable of cooling global temperatures for years due to the massive amounts of sulfur and ash released. ○ They are considered the most dangerous type of volcano due to the scale of their potential impact. Submarine Volcano ○ These volcanoes are found on the ocean floor, and some are active. ○ In shallow water, submarine volcanoes can blast steam and rocky debris above the surface of the sea. ○ They can be detected using hydrophones and sometimes cause discoloration of the water due to volcanic gasses.  Mud Volcano ○ Mud volcanoes are formed by geo-excreted liquids and gasses. ○ They can vary in size, with the largest structures reaching up to 700 meters high and spanning 10 kilometers in diameter. ○ Examples: El Totumo in Colombia and mud volcanoes in Buzău, Romania. Classification of Volcanoes by Activity Active (Awake) Volcanoes ○ Active volcanoes have erupted recently and have the potential to erupt again at any time. ○ Examples of active volcanoes in the Philippines: Mayon: Has erupted 47 times since 1616. Taal: Erupted more than 30 times since the 16th century. Kanlaon: Erupted 30 times since 1819. Bulusan: Erupted 15 times since 1885. Hibok-Hibok: Erupted five times in modern history. Pinatubo: Erupted in 1991 after 600 years of dormancy. Dormant (Sleeping) Volcanoes ○ Dormant volcanoes have not erupted in recent times but have records of past eruptions. ○ They can become active again after a period of dormancy. ○ Example: The lake in the caldera of a dormant volcano at Krafla in Iceland. Extinct Volcanoes ○ Extinct volcanoes have no recorded history of eruption and are not expected to erupt again. ○ Examples: Mount Mazama (Crater Lake) and Huascarán in Peru, Mount Buninyong in Australia. Pre-Eruption Activities Increased earthquake activity beneath the volcanic cone. Rise in temperature around the cone. Melting of ice or snow in the crater. Swelling of the cone. Steam eruptions and minor ash emissions. Types of Eruptions Explosive Eruptions: These occur when trapped gasses in thick, granitic magma violently explode due to high pressure. This type of eruption is highly destructive. Quiet Eruptions: These eruptions involve low-pressure gasses and more fluid, basaltic magma. Lava flows are typical of quiet eruptions, which are less violent but still hazardous. Types of Magma Basaltic Magma: Contains 45-53% silica, is rich in iron, magnesium, and calcium, and has a temperature range of 1000-1200°C. It is associated with fluid lava flows. Andesitic Magma: Contains moderate amounts of minerals, with a temperature range of 800-1000°C, commonly associated with stratovolcanoes. Granitic (Rhyolitic) Magma: Contains 20% more silica, rich in quartz and potassium, and has a temperature range of 650-800°C. This type of magma is thick and leads to explosive eruptions. Types of Volcanic Eruptions Magmatic Eruptions: Driven by gas decompression within magma, leading to various eruption styles: ○ Hawaiian: Gentle basaltic lava flows in jets. ○ Strombolian: Mildly explosive, with bursts of lava and rocks. ○ Vulcanian: Explosive eruptions due to thick magma plugs. ○ Plinian: Violent gas blasts that eject ash and pumice into the stratosphere. ○ Pelean: Known for pyroclastic flows of incandescent material. Phreatomagmatic Eruptions: Caused by interactions between magma and water: ○ Surtseyan: Shallow-water eruptions. ○ Submarine: Underwater eruptions that form seamounts and islands. ○ Subglacial: Eruptions beneath glaciers, where lava interacts with ice. Phreatic Eruptions: Steam-driven explosions caused by the heating of groundwater without direct magma involvement. Volcanic Processes Intrusion: Magma rises inside a volcano without reaching the surface, forming underground features. Extrusion: Magma rises and causes the volcano to erupt. The section also discusses intrusive volcanic features: Volcanic Necks: Hardened magma within the vent of an extinct volcano. Sills: Magma sheets that are parallel to surrounding rock layers. Dikes: Vertical magma sheets that cut through rock layers, serving as channels for magma. Volcanic Materials Lava: Molten rock that solidifies upon cooling. Three types of lava are highlighted: ○ Pahoehoe Lava: Hot, thin, and fast-flowing with a smooth surface. ○ Aa Lava: Cooler, thicker, and slow-moving with a rough surface. ○ Pillow Lava: Forms when lava is rapidly cooled by water, creating sack-like segments. Tephra: Also known as pyroclastic material, tephra consists of fragments ejected during an eruption, ranging in size from volcanic ash to large volcanic bombs. Gasses: Volcanic eruptions release various gasses, including water vapor (H2O), carbon dioxide (CO2), nitrogen (N2), sulfur dioxide (SO2), hydrogen sulfide (H2S), and others. Lahars (Mudflows): Mixtures of volcanic ash, water, and eroded land, which can be highly destructive as they flow down river valleys at high speeds. Volcanic Eruption Benefits Mineral Deposits: Volcanic activity brings valuable minerals to the surface. Soil Fertilization: Volcanic ash enriches the soil, promoting plant growth. Geothermal Energy: Heat from volcanic areas can be harnessed to generate electricity and heat buildings. Land Formation: Lava flows can create new landmasses, such as islands. Characteristics of Stars Definition: Stars are massive celestial bodies primarily composed of hydrogen and helium. They produce light and heat through nuclear fusion occurring in their cores. Distance: Stars, apart from the Sun, are located light-years away from Earth. Differences Between Stars and Planets Stars Planets Undergo nuclear reactions that burn Do not undergo nuclear reactions. hydrogen. Generally more massive. Typically less massive. Formed from gas clouds in nebulae Formed from materials condensing collapsing under gravity. around a star. Twinkle due to atmospheric disturbances. Do not twinkle; appear larger and closer. Can be found anywhere in the sky. Always located along the ecliptic plane. Appear static, but actually move over time. Move slowly against the background stars. Spectral Types of Stars Stars are categorized into spectral types based on their surface temperature and color. The types are ordered from hottest to coolest: O-type Stars: ○ Color: Blue ○ Temperature: 25,000–50,000 K ○ Characteristics: Extremely luminous, with lines of ionized helium in their spectra. B-type Stars: ○ Color: Blue-white ○ Temperature: 10,000–25,000 K ○ Characteristics: Moderately luminous, showing neutral helium lines. A-type Stars: ○ Color: White ○ Temperature: 7,400–10,000 K ○ Characteristics: Prominent hydrogen lines. F-type Stars: ○ Color: Yellow-white ○ Temperature: 6,000–7,400 K ○ Characteristics: Exhibits spectral lines caused by metals.  G-type Stars: ○ Color: Yellow ○ Temperature: 5,000–6,000 K ○ Characteristics: Includes our Sun; converts hydrogen to helium. K-type Stars: ○ Color: Orange ○ Temperature: 3,500–5,000 K ○ Characteristics: Cooler, with a range of spectral lines. M-type Stars: ○ Color: Orange-red ○ Temperature: ~3,000 K ○ Characteristics: Prominent titanium oxide lines. Supergiant Stars Supergiants are among the largest stars in the universe, formed when a star exhausts its hydrogen and begins burning helium. They have a short lifespan, often ending in supernova explosions, which can create black holes or neutron stars. Types of Supergiants Blue Supergiants: Very hot and luminous, ending in supernovae. Red Supergiants: Large, cool, and luminous; an example is Betelgeuse. Brown Dwarfs Brown dwarfs are substellar objects that are too massive to be planets but not massive enough to sustain hydrogen fusion, thus lying between the category of stars and planets. Life Cycle of a Star Constellations Constellations are patterns of stars perceived as distinct shapes in the sky. They appear to move due to the Earth's rotation. Types of Constellations North Circumpolar Constellations: Always visible and move in a circular path around the North Star. Equatorial Constellations: Positioned near the celestial equator. Zodiacal Constellations and Star Signs Aries (The Ram) Taurus (The Bull) Gemini (The Twins) Cancer (The Crab) Leo (The Lion) Virgo (The Virgin) Libra (The Scales) Scorpio (The Scorpion) Sagittarius (The Archer) Capricorn (The Goat) Aquarius (The Water Bearer) Pisces (The Fish) Climate and Weather Key Definitions: Climate: The average weather conditions in a region over a long period. Weather: The short-term state of the atmosphere, such as temperature and precipitation, in a specific place. Climate Zones: Polar Climate: Short spring, summer, and fall seasons. Temperate Climate: Mild temperatures, seasonal changes, and varied precipitation. Good for growing crops. Tropical Climate: Warm climate with little seasonal variation. Factors Affecting Climate: Latitude: Distance from the equator affects temperature (closer = warmer, farther = cooler). Air Pressure: ○ Low pressure: Warm, moist air rises, forming clouds. ○ High pressure: Cold, dry air sinks, leading to clear skies. Mountain Barriers: The Rain Shadow Effect occurs when mountains block rain, leading to deserts on the leeward side. ○ Windward side: Receives moist air and has a cold, wet climate. ○ Leeward side: Has little precipitation and a dry climate. Elevation: Higher elevations are cooler due to lower air density.  ○ Temperature drops 3.6°F per 1000 feet increase in altitude. Continental Location: Proximity to water stabilizes temperatures (land heats and cools faster than water). Coastal areas have more stable temperatures. Ocean Currents: Warm currents bring heat, cold currents cool nearby lands. Wind Belts: ○ Trade Winds, Westerlies, and Polar Winds are caused by air moving from high to low pressure zones. Storms: Occur when air masses with different temperatures meet. ○ Thunderstorms: An electrical storm characterized by lightning and thunder. ○ Tornadoes: A rotating column of air in contact with both the earth and a cumulonimbus cloud. ○ Hurricanes: A tropical cyclone with a low-pressure center, strong winds, and heavy rainfall. Weather Elements: Temperature: Measured in °C, °F, or Kelvin (K).  Wind: Air movement from high to low pressure. Day: Sea breeze; Night: Land breeze. Coriolis Effect: Earth's rotation causes winds to deflect from their path. Air Pressure: The weight of air above an area; measured in millibars (mb). ○ High pressure = fair weather ○ Low pressure = stormy weather Humidity: Amount of water vapor in the air. Types: ○ Absolute: Water content in the air. ○ Relative: Current humidity relative to maximum for that temperature. ○ Specific: Ratio of water vapor to air content. Clouds: Formed by water vapor condensing on tiny particles. Types: ○ Cumulonimbus: Thunderstorm clouds ○ Cirrus: High, thin, and wispy clouds ○ Nimbostratus: Rain clouds Precipitation: Types: Rain, snow, sleet, hail, etc. Hydrologic Cycle: Water movement through the atmosphere and Earth. Includes processes like: ○ Condensation: Water vapor in the air turns into liquid, forming clouds. ○ Deposition: Water vapor changes directly into ice without becoming liquid. ○ Percolation: Water flows through soil and rocks under gravity. ○ Evaporation: Water changing from liquid to gas. ○ Precipitation: Condensed water falling to Earth. ○ Sublimation: Solid to gas without passing through liquid. ○ Transpiration: Water vapor released from plants. Natural and Human-Driven Climate Change: Acid Rain: Forms when sulfur dioxide (SO2) and nitrogen oxides (NO) mix with water vapor. Effects include: ○ Harm to marine life ○ Tree and plant death ○ Structural corrosion ○ Health problems Global Warming: Causes: Emissions of greenhouse gases (GHG) like carbon dioxide (CO2), methane (CH4), and water vapor. Effects: Rising temperatures, stronger storms, melting polar ice, species extinction, and wildfires. Vital Signs of the Planet: Increasing CO2 levels (416 ppm in 2019). Global temperature has risen by 2.1°F since 1880. Declining Arctic ice and rising sea levels. Greenhouse Gasses (GHG): Water Vapor (H2O): Most abundant in the atmosphere. Carbon Dioxide (CO2): Significant contributor to warming. Methane (CH4), Nitrous Oxide (N2O), Ozone (O3), and CFCs also play key roles. Acronyms: UNEP: United Nations Environment Programme ITCZ: Intertropical Convergence Zone IPCC: Intergovernmental Panel on Climate Change WMO: World Meteorological Organization PAGASA: Philippine Atmospheric, Geophysical and Astronomical Services Administration DOST: Department of Science and Technology Weather Instruments: 1. Anemometer: Measures wind speed. 2. Wind Vane: Indicates wind direction. 3. Barometer: Measures atmospheric pressure. 4. Hygrometer: Measures humidity. 5. Rain Gauge: Measures rainfall.