DEFINITIONS

• Volcano


  derived from the word “vulcan” which is an island in Italy and/or the God of Fire in the Roman Mythology.
• Volcano


  is an opening in the earth's crust through which molten lava, ash, and gases are ejected. It is generally located in areas where the tectonic plates diverge or converge with each other.
• SHIELD VOLCANO


  type of volcano built entirely or mostly from fluid lava vents. It can measure for about hundreds of miles across and many tens of thousands of feet high.
• CINDER CONE VOLCANO 


  normally small about a miles span and about one thousand feet vertically. This volcanoes consist of mostly loose, grainy cinders and have very little to no lava.
• COMPOSITE VOLCANO


  also called “Strato Volcano.” consist of lava that is mixed with sand or gravel which in turn creates cinders or volcanic ash.
• CALDERA GIANT VOLCANO 


  This volcanoes are circular depressions in the ground over a magma chamber. This type of volcano is easier to notice from space due to the distance and viewpoint.
• FISSURE VOLCANO


  This volcanoes have no main crater, the ground just splits and lava pours out through the cracks. They are also hard to recognize from the ground and sometimes from space.
• Active volcano An active volcano is a volcano that has had at least one eruption during the past 10,000 years. Active volcanoes are the type of volcanoes that in general have been active for a certain period of time.
• Dormant volcanoDormant volcanos are the that are quiet volcanoes, but might possibly erupt again
• Extinct volcano


  Volcanoes are often considered to be extinct if there are no written records of its activity.
• HAWAIIAN ERUPTION


  fluid basaltic lava is thrown into the air in jets from a vent or line of vents (a fissure) at the summit or on the flank of a volcano.
• STROMBOLIAN ERUPTION


  eruptions involve moderate bursts of expanding gases that eject clots of incandescent lava in cyclical or nearly continuous small eruptions.
• VULCANIAN ERUPTION


  a short, violent, relatively small explosion of viscous magma.
• PELEAN ERUPTION


  associated with explosive outbursts that generate pyroclastic flows, dense mixtures of hot volcanic fragments and gas.
• PLINIAN ERUPTION


  They are caused by the fragmentation of gassy magma and are usually associated with very viscous magma.
• ICELANDIC ERUPTION


  from small effusive eruptions where lava flows quietly from fissures and crater rows to significant explosive eruptions in ice-covered central volcanos that produce large ash plumes
• Lava Flows


  are stream-like flows of incandescent molten rock erupted from a crater or fissure. When lava is degassed and/or very viscous, it tends to extrude extremely slowly, forming lava domes.
• Ashfall or Tephra fall 


  are showers of airborne fine- to coarse-grained volcanic particles that fallout from the plumes of a volcanic eruption; ashfall distribution/ dispersal is dependent on prevailing wind direction.
• Pyroclastic flows and surges (Pyroclastic density current)


  are turbulent mass of ejected fragmented volcanic materials (ash and rocks), mixed with hot gases (200°C to 700°C to as hot as 900°C) that flow downslope at very high speeds (>60kph). Surges are the more dilute, more mobile derivatives or pyroclastic flows.
• Lahars 


  are a rapidly flowing thick mixture of volcanic sediments (from the pyroclastic materials) and water, usually triggered by intense rainfall during typhoons, monsoons and thunderstorms. It can occur immediately after an eruption or can become a long-term problem if voluminous pyroclastic materials erupted such as the case of 1991 Pinatubo eruption. It can also occur long after an eruption has taken place such as the lahars at Mayon Volcano after the 1984 eruption.
• Volcanic gases


  gases and aerosols released into the atmosphere, which include water vapor, hydrogen sulfide, sulfur dioxide, carbon monoxide, hydrogen chloride, hydrogen fluoride.
• Debris avalanche or volcanic landslide


  massive collapse of a volcano, usually triggered by an earthquake or volcanic eruption. An example of a recent debris avalanche event occurred during the 1980 eruption of Mt. St Helens. Based on present morphology of volcanoes, Iriga Volcano in Camarines Sur, Banahaw Volcano and Quezon Province and Kanlaon Volcano had pre-historic debris avalanche events.
• Tsunami


  sea waves or wave trains that are generated by sudden displacement of water (could be generated during undersea eruptions or debris avalanches)
• Tsunami


  a term which originated from the Japanese “tsu”, which means harbor, and “name”, which means wave, is a series of waves generated when an oceanic body of water is rapidly disturbed because of an underwater earthquake, volcanic eruption, landslide or underwater explosion, and whose height could be greater than 5 meters
• Local tsunamis


  are confined to coasts within a hundred kilometers of the source usually earthquakes and a landslide or a pyroclastic flow. It can reach the shoreline within 2 to 5 minutes. 
• Far field or distant tsunamis


  can travel from 1 to 24 hours before reaching the coast of the nearby countries.PTWC (Pacific Tsunami Warning Center) and NWPTAC (Northwest Pacific Tsunami Advisory Center) are the responsible agencies that closely monitor Pacific-wide tsunami event and send tsunami warning to the countries around the Pacific Ocean.
• Soil erosion


  is a gradual process that occurs when the impact of water or wind detaches and removes soil particles, causing the soil to deteriorate. Soil deterioration and low water quality due to erosion and surface runoff have become severe problems worldwide.
• landslide


  is a movement of earth, rock, or debris due to gravity. It can be caused by continuous heavy rainfall, strong earthquakes, or human activities.
• Landslide


  massive outward and downward movement of slope-forming materials, it is restricted to movements of rocks and soil masses. These masses may range in size up to entire mountainsides. Their movements may vary in velocity.
• Rotational Slides


  move along a surface of rupture that is curved and concave
• Translational Slides 


  occur when the failure surface is approximately flat or slightly undulated
• Rock Fall


  Free falling detached bodies of bedrock (boulders) from a cliff or steep slope
• Rock Toppling


  occurs when one or more rock units rotate about their base and collapse
• Lateral Spreading


  occurs when the soil mass spreads laterally and this spreading comes with tensional cracks in the soil mass
• Debris Flow


  Down slope movement of collapsed, unconsolidated material typically along a stream channel
• Earthflow 


  Earthflows exhibit an hourglass shape, with slope material liquefying and flowing downhill, forming a depression at the top.
• Creep


  refers to the slow, continuous downhill movement of soil or rock due to shear stress, causing permanent deformation without reaching shear failure.
• Gravity


  works more effectively on steeper slopes
• Geological Factors


  Geology setting that places permeable sands and gravels above impermeable layers of silt and clay or bedrock
• Heavy and Prolonged Rainfall


  slides occur often with intense rain by creating zone of weakness, also water tables rise with heavy rain making some slopes unstable