SCIENCE Q3

• Volcano is a mountain formed by the accumulation of lava and volcanic ash.
• Volcano is a rapture, vent, or fissure on the crust of a planetary-mass object.
• Origin of the word Volcano:

  Derived from "vulcano" whose name in turn originates from Vulcan from Roman Mythology
• Volcanology - the study of volcanoes
• Volcanologists - scientists/people who study volcanology
• Adiabatic expansion in volcanoes refers to the process where the magma and its associated gases change temperature and pressure without exchanging heat with the surrounding environment. 
• Plate tectonics is a scientific theory that explains how major landforms are created as a result of Earth's subterranean movements.
• A tectonic plate (also called a lithospheric plate) is a massive, irregularly shaped slab of solid rock, generally composed of both continental and oceanic lithosphere.
• Plate tectonics - the movements of place and the geological process of volcano formation
• Crust describes the outermost shell of a terrestrial planet
• Convection Current - the repeated rising and sinking of materials creates convection currents that create horizontal forces on the plate of the Earth, causing plates to move.
• Volcanoes are generallycreated due to plate tectonics.
• TRUE- The continental crust is less dense than the oceanic crust, thus, during the collision of two plates, the continental plate rides over the top of the oceanic crust.
• LITHOSPHERE

  • includes the crust and part of the upper mantle
  • made up of tectonic plates that are in constant motion due to convection currents in the mantle
• Asthenosphere

  • layer of Earth's mantle lying beneath the lithosphere
  • layer of solid rock that has so much pressure and heat the rocks can flow like a liquid
• Core

  • composed mainly of an iron and nickel alloy
  • source of internal heat
  • makes the magma rotate by its heat
• Convergent Plate Boundaries - plate boundary where tectonic plates meet or collide
• Divergent Plate Boundaries- plate boundary where tectonic plates are moving away from one another
• Divergent Plates:

  At the mid-oceanic ridges, two tectonic plates move away from one another as new oceanic crust is formed by the cooling and solidifying of rising hot molten rock.
• Divergent Plate:

  Most divergent plate boundaries are at the bottom of the sea, thus, most volcanic activity is submarine such as the Black Smokers.
• Convergent Plate:

  At the subduction or convergent zones where two plates meet, the oceanic crust subducts under the continental plate.
• Convergent Plate:

  Frictional heating is likely to occur along the boundary between the subducted plate and the overlying mantle wedge.
• Flux Melting - a process on where water is released from the subducting plate and lowers the melting temperature of the overlying mantle wedge that creates magma; magma that reaches the surface and forms the volcano.
• Hotspots - these are the volcanic areas believed to be formed by the mantle plumes or the columns of hot material rising from core-mantle boundary.
• Magma chamber - large underground pool of liquid rock found beneath the earth's crust
• Conduit - channelways that lead from the magma reservoir to the vent
• Vent - weak point in the Earth's crust where hot magma has been able to rise from the magma chamber and reach the surface
• Throat - uppermost section of the main vent

  - area where the lava and volcanic ash are ejected
• Apex - the highest point or the summit of a volcano
• Cone - most striking part a volcano

  - usually composed of mixtures of lava and pyroclastic
• Flank - side of a volcano
• Sills - known as instrusive sheets

  - solidified lava flows that originally forced their way between and parallel to older layers of rocks
• Dikes - tabular or sheet-like bodies of magma that cut through and across the layering of adjacent rocks
• Parasitic Cone - is a secondary cones build up around secondary vents that reach the surface on larger volcanoes. As they deposit lava and ash on the exterior, they form a smaller cone, one that resembles a horn on the main cone.
• Crater - basin-like depression over a vent at the summit of the cone
• Caldera - volcanic depression much larger than the original crater
• Lava - rock or magma expelled from a volcano during eruption

  - temperature upon ejection can reach up to 700*C hence it flows until it cools and harden
• PAHOEHOE - the lava with a ropelike surface texture and has a low viscosity lava.
• AA - a blocky rough lava flow.
• Lava Tube - a tube formed by cooling and solidifying of the lava walls while fluid lava continued to flow inside