volcanoes

• the magma chamber is the place where molten rock collects
• Stratovolcanoes, also known as composite volcanoes, are tall conical volcanoes built up by layer upon layer of lava flows and volcanic ash erupted during intermittent explosions.
• Shield volcanoes are broad and gently sloping, with fluid lava flows and non-explosive eruptions.
• Cinder cones are small, steep-sided volcanic mountains composed almost entirely of loose pyroclastic fragments such as cinders, ash, and small lava fragments.
• Lava domes are rounded volcanic masses formed by highly viscous lava that piles up onto the summit of a volcano.
• when magma rises to the surface it becomes lava
• Both Cinder and shield volcano have lava type of basalt
• Stratovolcano has a high viscous andestic lava type
• A volcano is generally a rupture from the earth's crust or an elevated landform with an opening called a crater that releases molten rock
• Magma Chamber


  underground compartment where magma is stored
• Conduit


  Passageway through which magma travels to reach Earth's surface
• Vent


  opening through which volcanic materials are released
• Crater

  Bowl-shaped depression at the top of the volcano where the vent is located
• When stratovocanoes explode, an area of the volcano may collapse, forming a larger crater and depression called caldera.
• Composite volcanoes are formed from multiple eruptions over thousands of years
• Unloading is when a rock’s weight decreases dramatically geological processes such as earthquakes, avalanches, or landslides can remove materials such as rocks or ice. This process lowers the lithostatic pressure and expands the materials. The expansion makes the surface crack upward causing an eruption to happen.
• Hydrothermal alteration is a process that happens when the heat, fluids, and gases inside the magma are too strong for the rock to hold it back. They eat away at the rock, and can slowly cause hard rock to transform into clay. This process essentially lowers or decreases the strength of the rock layer.
• Ocean to ocean/continent boundaries have subduction zones. Subduction zones allow for water to get into the mantle, and that creates partial melting. The partial melting creates pressure and gases that cause eruptions.
• The delicate balance of lithostatic and magmastatic pressure, along with the strength of the Earth's crust, determines whether magma stays underground or erupts as a volcano.
• An increase in magmastatic pressure can cause explosive volcanic eruptions due to the formation of high-pressure gas bubbles.
• Shield volcanoes have a very large, steep-walled caldera at the summit
• A shield volcano is formed by loose and fluid lava over layers of solidified lava from previous eruptions
• A cinder cone is formed when pressure builds up in the magma chamber, ejecting fluid lava high into the air
• When a volcano erupt there will be:

  1. Lahar or lava flow
  2. Fires
  3. Loss of property
  4. Casualties
  5. Water and air pollution
  6. Disturbance in weather/climate patterns
• Lava dome volcanoes form when extremely viscous lava rises and then hardens into a dome shape. These emerge in a one active period.
• Collisions between tectonic plates deform rocks and trigger a buildup of temperature that causes the rocks to melt, creating magma
• Ash pume is the cloud of ash that comes out of the crater
• The different types of volcanic eruption are hawaiian, strombolian, vulcanian, and plinian
• A hawaiian eruption is the least violent type, with highly fluid or runny lava flowing out of the volcanoes vents. Hawaiian eruptions lead to the formation of shield volcanoes
• A strombolian eruption if violent, marked by continuous ejection of magma and gas, resulting in the formation of volcanic ombs and cinder cones
• In a vulcanian eruption, viscous lava flows are produced
• A plinian eruption is the most violent and explosive type of eruption caused b build up of viscous magma and dissolved gas