1st Exam Reviewer

• Earth's surface is composed of major and minor tectonic plates
• These plates overlying the semi-solid, plastic-like asthenosphere are in constant motion.


  It tends to move towards or away from each other, thus, forming mountains or volcanoes.
• The Philippines is in a zone within the Pacific ocean that covers a collection of moving plate edges forming a “ring” of volcanoes that cause earthquakes.
• Pacific Ring of Fire or the Circum-Pacific belt


  a zone within the Pacific ocean that covers a collection of moving plate edges forming a “ring” of volcanoes that cause earthquakes.
• The Pacific Ring of Fire


  is a 40 000-kilometer, a horseshoe-shaped basin that is associated with oceanic trenches, volcanic arcs, and plate movements. Around 75% of the world’s active and dormant volcanoes can be found in this region
• Philippines


  is an archipelago surrounded by subducting plates that provide the ideal condition for volcanic formation resulting to highly active seismicity and volcanism in the country.
• Tectonic Activity in the Philippines


  is one of the most active in the world characterized by a number of earthquakes and active volcanic activities. This is due to the interaction of tectonic plates comprising the archipelago.
• Most active volcanoes in the Philippines are found in volcanic arcs
• Volcanic Arcs


  are chains of volcanoes formed by subducting plates. It is formed through the subduction of an oceanic tectonic plate under another tectonic plate result in the formation of volcanic arcs.
• Oceanic Plate


  is saturated with water and thus affect the melting point of the mantle
• The subduction of the plates goes deeper which increases the pressure acting on it
• Subuction


  The process will form magma ascends to form an arc of volcanoes parallel to the subduction zone.
• There are two forms of the volcanic arc that can be formed
• Oceanic Arc


  When oceanic crust subducts beneath another oceanic crust on an adjacent plate
• Continental Arcs


  formed when oceanic crust subducts beneath continental crust on an adjacent plate, creating an arc-shaped mountain belt and stratovolcanoes.
• There are five distinct volcanic arcs in the Philippines where the volcanically active region can be found

  the Luzon Volcanic Arc, the East-Philippine Volcanic Arc, the Negros-Panay Arc, the Sulu-Zamboanga Arc, and the Cotabato Arc.
• Emission of gases, flowing of lava outside the surface and sudden violent explosive bursts are some of the characteristics that describe a volcanic activity
• Magma


  Buoyant molten rock
• Some of these molten materials may ascend to the Earth’s surface and are extruded as lava during a volcanic eruption.
• Active volcanoes

  are those that erupted within the last 10 000 years.
• Active volcanoes can be indicated by historical reports or radiometric dating
• As of 2008, PHIVOLCS listed 23 active, 26 potentially active and 281 inactive volcanoes
• Out of 23 active volcanoes, 21 had historic eruptions
• Mayon Volcano (Albay)


  is the most active volcano in the country. It is famous because of its almost perfect cone shape
• Mayon Volcano (Albay)


  It is a stratovolcano with an elevation of 2.46 kilometers and a base diameter of 20 kilometers
• Stratovolcano


  is one of the three types of volcano commonly characterized by a conical shape, nearly symmetrical structure with a steep summit and more gradually sloping sides
• Mayon Volcano (Albay)


  Its latest eruption activity was a lava dome growth on January 2018.
• Taal Volcano (Batangas)


  It is a volcanic caldera composed of several active volcanic landforms making it a complex type of volcano.
• Caldera


  is a volcanic landform associated with depression in a circular form and has a diameter exceeding one kilometer.
• Main Crater Lake


  1.9 kilometers in diameter and located 4 meters above sea level.
• It is a popular misconception that the crater that can be seen in Tagaytay is the Taal volcano itself.

  It is the parent volcano of Taal called Binintian Volcano
• Taal Caldera (Batangas)


  is 25 kilometers across and within it is Taal Lake, which has an area of 267 km2 and located 2 meters above sea level.
• Taal Volcano (Batangas)


  There are a total of 47 craters and four maars in Taal Volcano Island. The most recent activity of this volcano was noted last April 2011.
• Kanlaon Volcano (Negros Oriental)

  It is 2.435 kilometers in elevation with a base diameter of 30 kilometers. Its latest activity was on June 18, 2016, according to PHIVOLCS.
• Bulusan Volcano (Sorsogon)


  It is a stratovolcano formed inside a caldera. It has several craters and fractures along with four different hot springs adjacent to it. It is 1.599 kilometers in height and has a base diameter of 15 kilometers. Its latest activity was on March 2, 2017.
• Potentially Active Volcanoes


  do not have any historical record of any eruption but are considered as morphologically young. There are also suspected seismic activity and documented local ground deformation
• Babuyan Claro


  Cagayan
• Banahaw


  Laguna, Quezon
• Biliran


  Biliran Island
• Bud Dajo


  Sulu