sci (quiz 1)

• PHIVOLCS (PHILIPPINE INSTITUTE of

  VOLCANOLOGY and SEISMOLOGY)

  • is a service institute of DOST (Department of Science and Technology) that is mandated to mitigate disasters that may arise from volcanic eruptions, earthquakes, tsunamis and other related geotectonic phenomena.
• VOLCANOES - are mountains with vents and craters that serve as a pathway for lava and molten rocks coming from the magma chamber. There is a rupture in the Earth's crust on which fragments of rocks, hot gases and lava escape from the surface undergrounds.
• (outer part)

  Summit - is the highest peak of the volcano through which either crater or caldera can be seen
• (outer part)

  Slope - is the side of the volcano
• (outer part)

  Base - is the flat surface that holds the entire volcano
• Magma chamber or magma reservoir - is located far beneath the surface of the earth which contains the magma or molten rock.
• 1. Conduit or main vent - is the pipe or vent where volcanic material wells up from beneath the surface. It connects the magma chamber to the opening or mouth of a volcano.
• Crater - is a funnel-shaped or bowl-shaped depression that lies directly above the vent of a volcano from which volcanic materials are ejected during eruption.
• Caldera - is basin-shaped depression formed when the side of a volcano collapsed after a violent eruption.
• Side vents - an opening in the side of a volcano through which volcanic materials erupt.
• Molten rocks ejected beyond the surface of the Earth is called magma. It may contain crystals, minerals, fragments of unmelted rocks and hot gases.
• When the magma flows out of the crater and reaches the surface of the Earth it is then called lava. The solidified lava turns into an igneous rock.
• Active volcanoes - are those that shown eruption for the past 600 years based on the analysis of volcanic deposits. (e.g. Mount Mayon, Taal Volcano, Mount Kanlaon)
• Potentially Active volcanoes are morphologically young looking

  volcanoes but do not have any history of eruptions. (e.g. Mount Arayat)
• Dormant volcanoes - have not erupted for the past 500 years but has the chance to erupt again
• Extinct volcanoes - are those that do not erupt for the past 5000 years and do not have the chance to erupt again. (e.g. Mount Apo in Davao, is a dormant stratovolcano in Mindanao. It is the tallest mountain the Philippine Archipelago.)
• Composite Volcano - also refer as stratovolcano. It is consists of alternate layers of lava and pyroclastic flow. It has steep side and symmetrical cones with huge base developed by lava flows, volcanic ashes, blocks of stones and bombs. It is the tallest among the three cones. (e.g. Mount Mayon)
• Cinder Volcano - has steep slopes and wide crater and considered as the simplest type of volcanic cone. It is constructed from semi-fluid lava ejected from the vent. They are also called ash cone they are formed by pyroclastic rock fragments or cinders which accumulate and gradually build a conical hill and a bowl-shaped crater at the top.
• Shield volcanoes - are flat and vast volcanoes. It has a slope that covers the area. Lava is less viscous and explode at low intensity. It does not explode or erupt violently.
• Effusive eruption - occurs when hot runny basaltic magma reach the surface as dissolved gases and lava escape easily. There is minimal or almost no gas upon eruption.
• Explosive eruption -happens in steep slope volcanoes, with viscous magma and slow moving lava that prevents the release of hot gases, resulting in pressure and violent eruption of the volcano.
• VOLCANIC EXPLOSIVITY

  INDEX (VEI) - is an instrument used to determine the magnitude of an explosive eruption based on the total volume of erupted material called tephra.
• Factors that affect the degree or style of volcanic eruptions

  1. The magma chemistry and content
  2. The magma's temperature
  3. The viscosity of the magma
  4. The volume of how much water and dissolved gases in the magma
• Phreatic - also called as hydrothermal which is a steam driven type of eruption as hot rocks come in contact with water.
• Phreatomagmatic - is a violent eruption due to the interaction between water and magma. If the magma rises very slowly within the conduit or throat of the volcano, gases escape resulting in violent eruption.
• Strombolian - is a type of volcanic eruptions with relatively mild blast having a VEI of 1-3. The eruptions are small to medium in volume and sporadic violence. It is characterized by fountains of lava.
• Vulcanian - characterized by tall eruption columns reaching up to 20 km high with pyroclastic flows and ash fall tephra.
• Plinian - considered the most violent type of eruption exemplified by the fragmentation of highly gas charged and viscous magma. Mixtures of hot ash, gas could reach the stratosphere.
• VOLCANIC HAZARDS - are phenomena arising from volcanic activity that pose potential threat to people or property.
• Pyroclastic Flow - Fast turbulent flow of fragmented volcanic materials (ash and rocks) mixed with hot gases.
• Lava Flow - Flow of molten rock materials.
• 1. Ash/Tephra Fall - Shower of fine-to-course-grained fragmented materials resulting from a volcanic eruption. Ash fall distribution or dispersal is dependent on prevailing wind direction.
• Lahar - Rapidly flowing thick mixture of volcanic materials and water.
• Volcanic Gases - Gases released from volcanoes. Most abundant gas released is water vapor which is harmless.
• crust - mantle - outer core - inner core
• Geothermal Energy - comes from the heat inside the Earth.

  > the word "geothermal" comes from the Greek words geo, which implies "earth," and thermal, means "heat."
• People around the globe use geothermal energy to produce electricity, to heat and cool buildings and to serve human activities.
• People benefit from geothermal energy through:

  1. geothermal power plant
  2. geothermal heat pump
• 1. Hot water is pumped from deep underground through a well under high pressure.
• 2. When the water reaches the surface, the pressure is dropped, which causes the water to turn into steam.