Volcanoes

• Volcano generally described as mountains that emit volcanic products (lava, rocks, gases) from the interior of the earth from its vents.
• lava and magma are different
• Magma chamber: where molten rock or magma is found
• vent: an opening through which an eruption takes place
• crater: the basin-like depression over a vent at the summit of a cone
• Different types of volcano according to shape

  • shield volcano
  • cinder cone
  • composite/stratovolcano
• more viscous, more dangerous
• viscous - ability of the fluid to flow
• Shield volcano

  • they are formed from fast flowing lava that flows easily over the surface
  • fluid lava(less viscous)
  • quiescent eruptions (less violent)
  • low slope (less 10 degrees)
• Shield volcanoes

  ex.

  1. Mt. Mauna Loa - hawaii

  • historically been considered the largest volcano on earth
  • 4, 170 m elevation

  2. Mt. Kanloan

  • highest mountain in the island of Negros
• Boundaries can form mountains and volcanoes.
• Cinder cone

  • they are formed from loose rock fragments ejected from a central vent
  • viscous lava
  • explosive eruptions
  • the ejecta (ejected particles) land near the vent, forming a cone with a slope of approximately 33 degrees
  • symmetrical, small diameter and height
• Cinder cones

  ex.

  smith volcano or Mt. Babuyan: an active volcano in Babuyan Island
• Composite volcanoes

  • they are formed from alternating layers of pyroclastics and lava
  • they have a viscous lava resulting to more explosive and more dangerous explosions
  • nearly symmetrical structure
• Composite volcanoes

  ex.

  Mayon volcano

  • the most famous active volcano of the Philippines
  • a perfect stratovolcano rising to 2, 462 m in the province of Albay in Bicol

  Mt. Fuji

  • in Japan
• Different types of Volcanoes according to activity

  • active volcano
  • inactive volcano
• Active volcano

  • one that has erupted since the last ice age (i.e, in the past - 10,000 years) - Global Volcanism Program
  • is in the violent phase with continuos or periodic eruption
  • can cause the ground to shake, ashfall
  • one that shows signs of unrest in the form of earthquakes swarms, inflation, abundant degassing of carbon dioxide and/or sulfur dioxide
• RING OF FIRE/PACIFIC RING OF FIRE

  • it is where volcanoes & earthquakes occur and formed
  • horseshoe arc of about 40, 000 kilometers hugging the edge of the Pacific Ocean
  • frequent earthquakes and volcanic eruptions due to the motion of tectonic plates
• Active volcano

  Ex.

  Mt. Etna

  • located in Sicily, Italy
  • one of the most famous active volcanoes
  • largest active volcano in Europe
  • first eruptions occurred 500,000 years ago
• Active volcano

  ex

  Stromboli

  • smaller than mount etna
  • located in Sicily, Italy
  • small explosions throw out glowing lava from several vents inside its summit crater
  • this activity has been going on for at least 2, 000 years ago
• Active volcanoes in the Philippines

  • Mayon volcano
  • Mt. Pinatubo
  • Taal Volcano
  • Mt. Hibok-Hibok
  • Mt. Bulusan
  • Mt. Kanloan
• Inactive volcano

  • dead volcano
  • one that is not usually expected to erupt in the future and have not erupted recently
  • one that has not erupted in the past 10, 000 years
• Dormant

  • sleeping volcano
• Examples of Inactive volcano

  Vulcan

  • named after the Roman god of fire
  • an inactive volcano on Albuquerque, New Mexico's West Mesa
• Ex. of inactive volcanoes in the Philippines

  Mt. Arayat

  • an inactive volcano in Pampanga, Philippines
  • rising to a height of 1, 033 m (3, 389 ft)
• Types of volcanic eruption

  • Phreatic
  • Vulcanian
  • Strombolian
  • Phreatomagmatic
  • Pelean
  • Plinian
• PHIVOLCS - Philippines Institute of Volcanology and Seismology
• Volcanic eruption

  • when lava and gas are released from a volcano
  • sometimes explosively
• Phreatic - water

  • also known as "steam-blast" eruption or ultravulcanian eruption
  • happens usually at vulcanian volcanoes
  • occurs when steam is produced from the contact of cold groundwater with hot rock or maga
  • during phreatic eruptions, no new magma is produced. Only fragments of preexisting solid rock in the volcano are expelled.
  • generally weak - USGS
• Vulcanian

  • named after Vulcano Island in Italy
  • characterized by an ash-filled gas explosion from the volcano's crater that shoots up above the peak to form a dense cloud near the upper level of the cone
  • the cloud formed can be gray or black
  • rock fragments and particles from a Vulcanian eruption are more widely spread, but not necessarily more in quantity
• Strombolian

  • named after the stromboli volcano in Italy
  • this type of eruption blasts fragments of solidified lava and rocks to altitudes of tens to hundreds of feet
  • form luminous arcs through the sky, produced from bursts of huge clots of molten lava from the volcano's summit crater - USGS
  • higher viscosity for lava and magma flows
  • activity can last up to a few years
• Phreatomagmatic

  • water and magma collision
  • a type of explosive eruption that results from magma erupting through water
  • the second phase of the Eyjafjallajokull eruption in 2010 - a result of magma erupting under ice
  • it can happen under water and not under
  • can form new lands
  • some submarine volcanoes are phreatomagmatic if the magma is gas-rich, for example- Surtsey in iceland
  • this eruption can formed a new island
• Pelean

  • also known as pyroclastic flows
  • named after Mt. Pelee in France's overseas region of Martinique
  • flows from the sides and the downs of the volcano
  • forms domes and glowing avalanches of hot ash that flows down the sides of a volcano
  • large quantities of gas, dust, ash, and lava fragments are also produced from the volcano's central crater
  • tephra - rock particle deposits, less widespread than those from plinian eruptions(generally)
  • one of the most dangerous kind of eruptions
  • can be devastating especially if it takes place in populated areas
• Plinian

  • one of the most dangerous type of eruption
  • known as the most powerful type of eruption
  • characterized by continuous gas blasts and explosive ejection of viscous lava, gas-rich magma and large volumes of volcanic rock known as pumice
  • can last less than a day to several months
• pinatubo 1991 explosion in Zambales s the second largest erupton of the 20th century
• Geothermal Energy

  • the internal heat of the earth
  • from the Greek word "geo," meaning Earth and "therme" meaning heat
  • the Philippines now rank as the 3rd largest power producer of geothermal energy next to United States of America and Indonesia
• Geothermal plants in the Philippines are located in:

  • Laguna
  • Sorsogon
  • Albay
  • Batangas
  • Negros Occidental
  • Leyte
  • North Cotabato
• Source of Geothermal Energy

  • Hydrothermal Reservoirs/Hot Springs
  • Geopressurized Resource
  • Hot Dry Rock Reservoir
• Hydrothermal Reservoirs/Hot springs

  • most common source of geothermal energy production worldwide
  • contains hot water and/ or steam trapped in fractured or porous rock formations
• Geopressurized Resource

  • from formations where moderately high temperature brines(water saturated or strongly impregnated with common salt) are trapped in a permeable layer of rock under high pressure