Volcanoes

• What is geomorphology?


  The study of the relief features of the Earth's crust.

  Geo - Earth

  morph - form

  ology - study of
• What are the three primary geologic forces?

  Diastrophism, erosion, and volcanism.
• Diastrophism - Caused by internal pressures of the vertical and horizontal movement of a portion of Earth's crust

  that results in mountains.
• Erosion - The physical removal of rock or the wearing down of landmasses by geomorphic agents. Caused by exogenous forces (forces outside the Earth's crust)
• Vulcanism - Also known as Volcanicity, refers to a variety of processes associated with the surface discharge of magma or hot water and steams, such as volcanoes, hot springs, geysers, and fumaroles.
• Geyser - The groundwater beneath the shallow surface is heated and it explodes into boiling water and scene.
• Fumarole - geothermic vent that emits volcanic gases like steam, carbon dioxide, nitrogen gas, carbon monoxide, ad hydrogen sulfide.
• Hot spring - Also called a thermal springa source of geothermically heated water rising to the surface of Earth's crust.
• What is an example of extrusive volcanism?

  Volcano
• Volcano - typically cone-shaped and formed through years of the extrusion of lava.
• Circle of Fire/Ring of Fire - belt of volcanoes that ring the Pacific Ocean. more than 75% of the 859 volcanoes are located here.
• Volcano is my named after the Roman God in Sicily. Vulcan.
• Formation of a Volcano

  They are built through the accumulation of their own eruptive products like the lava, ash flows, magma, etc.
• There are no active volcanoes in Australia
• Active volcano - currently erupting or shows sign of unrest such as significant amount of gas emissions or frequent seismic activities.
• Fumarolic stage - After emitting the materials, this is categorized by the emission of acid gases and vapor.
• Inactive/dormant Volcano - If it has not erupted in 2000 years. The volcano will progressively reduce in size overtime.
• Extinct volcanos - period of dormancy for over 10 000 years. Volcanos are cut off from their lava suppkly.
• How are volcanos categorized?


  Based on shape, the materials they are made of, and the way they erput,
• Cinder Cones


  Also called scoria cones. Sharp conical hill that is largely of made basalt. Seldom exceeding 250 m height and 500m diameter eh.
• Composite Volcanoes


  Also known as stratovolcano. Constructed by multiple explosions that is made out off pyroclastic elements and hardened lava flow.
• Shield Volcanoes


  Broad, gentle sloping landform by many layers of low-viscous lava flow
• Volcanic Domes


  A lava dome. Formed from viscous magma being erupted effusively.
• Supervolcanoes - A volcano has reached a magnitude of 8 on the Volcanic Explosivity Index (VEI). Produce the largest eruptions on Earth.
• Submarine volcanoes


  when magma erupts in the underwater fissures of the Earth. Majority are found near ocean ridges.
• Subglacial Volcanoes 


  Also called a glaciovolcano. Is created beneath the surface of a glacier or sheets which are then melted into a lake.
• Classifications of Volcanic Eruptions

  Explosive eruptions - gas-driven explosion that propels magma and teprha
• Classifications of Volcanic Eruptions

  Effusive explosions - outpouring of lava without significant explosive eruption.
• Magmatic Eruptions


  Hawaiian - Calmest eruption type. Named after Kilauea volcano which is know for producing beautiful fire fountains. Effusive emission of highly fluid basalt lava with little gas concentration.
• Magmatic Eruptions


  Strombolian - Driven by bursting od gas bubbles within magma. Short-lived but explosive.
• Magmatic Eruptions


  Vulcanian - Named after the Italian Island Vulcano which is believed to be the home of Hephaestus. When the pressure of entrapped gases in relatively viscous magma becomes efficient to blow off the overlying crust of solidified lava.
• Magmatic Eruptions


  Pelean - Also called nuee ardente. Occurs when a large quantity of gas, dust, ash, amd lava fragments are blown out of a volcano's central crater. One of the most dangerous volcanic activities because of the landslides they cause.
• Magmatic Eruptions


  Plinian/Visuvian - The most explosive and most powerful of all eruptions. An eruption with a magnitude of 8 according to the VEI is an ultra plinian eruption that happened at Lake Toba 74 000 years ago.
• Phreatomagmatic Eruptions


  Surtseysan - Named after the island of Surtsey off the coast of Iceland. A kind of hydromagmatic eruption. When an undersea volcano has finally matured enough to break the surface of the water.
• Phreatomagmatic Eruptions


  Submarine - Takes place beneath the surface of the water. About 100k deepwater volcanoes in the world. The final stage is the capping of a seamount in alkalic flows.
• Phreatomagmatic Eruptions


  Subglacial eruption - Also called glaciovolcanism, features interactin between lava and ice often under a glacier. Occurs in areas of high altitude and latitude.
• Phreatic Eruptions


  Called steam-blast eruptions. Driven by explosive expanding steam resulting from cold ground or surface water coming into contact with magma.