Tectonic Hazards

• (Composite) Stratovolcano is made up of layers of lava and ash which build up over time to form steep sided cones.
• Shield Volcano has a gentle slope with many fissure vents that erupt fluid basaltic magma. They have low viscosity so they flow easily.
• Hotspot is an area where molten rock rises through the crust
• Composite volcanoes are also known as stratovolcanoes, these are tall mountains built from alternating layers of hardened lava, pumice, rock fragments and ash. The layers can be seen on the sides of the mountain
• Plume is a stream of hot material rising from deep within the mantle
• The Hawaiian Islands are formed by a plume under the Pacific Plate, as it moves across the plume new islands are created on top of older ones.
• The Hawaiian islands were formed by hotspots beneath the Pacific Plate
• Volcanic explosivity index (VEI) measures how powerful a volcanic eruption was based on the amount of ejected material
• Pyroclastic Flow is a fast moving cloud of superheated gas and rock fragments that moves down the side of a volcano at speeds of more than 700km/h
• Volcanic Ash is fine particles of pulverised rock ejected into the air during explosive eruptions
• Tsunamis are large waves generated by earthquakes or volcanic activity
• Ashfall can be dangerous because it contains toxic gases such as sulfur dioxide and hydrogen chloride
• Shield volcano has a broad base with gentle slopes, formed by repeated eruptions of fluid basaltic magma
• There are four types of plate boundaries which are constructive, destructive-collision, destructive-subduction and conservative
• Destructive Plate Boundaries occur when two plates collide head on
• Constructive Plate Boundaries occur where two plates move away from one another
• Composite Volcanoes have steep sides and a central crater, formed from frequent violent eruptions of viscous andesitic lava
• Conservative Plate Boundaries occur when two plates slide past each other
• Constructive Plate Boundaries occur where new crust forms at mid-ocean ridges
• Collision occurs when two continental plates or an oceanic and continental plate meet
• The Ring of Fire is the area around the Pacific Ocean that experiences most earthquakes and volcanic activity due to subduction zones.
• Earthquakes occur due to the movement of tectonic plates, which are large pieces of the Earth's crust
• Tectonic plates are the broken down pieces of the Earth's crust which move slowly in different directions
• Plates can be either oceanic (made up of denser basalt) or continental (made up of less dense granite)
• Plates move due to convection currents inside of the mantle which pull the lithosphere along
• Convection currents form as hot rock rises from the core-mantle boundary and cooler rock sinks back into it
• Magnitude measures how much energy was released during an earthquake on the Richter scale
• Seismographs measure ground vibrations caused by seismic waves generated during earthquakes
• The epicentre is the point on the earth's surface directly above the focus of the earthquake
• Deep focus earthquakes start 70-700km below the surface and occur when an oceanic plate is subducted beneath a continental plate. They only occur at destructive plate boundaries.
• Shallow focus earthquakes are less than 70km deep and can happen anywhere, but most commonly occur at conservative and in the upper part of destructive or collision plate boundaries. They are more common, and cause widespread damage when felt.
• The Mercalli scale is a measure of the intensity of an earthquake.
• Intensity is measured based on observations made about the effects of the earthquake on people and buildings.
• The parts of an earthquake are the focus, epicentre, and the seismic waves

  A) Fault

  B) Focus

  C) Epicentre

  D) Seismic waves

  E) Pressure builds up
• Iceland has many active volcanoes due to its location above a hotspot (plume). The plume melts rock as it rises through the mantle causing magma to form which then erupts from fissures in the crust.
• Volcanic eruptions release gases such as sulfur dioxide into the atmosphere that react with water vapour to produce acid rain. This causes damage to crops and vegetation leading to loss of income for farmers.
• Acid rain also damages buildings and statues by dissolving limestone and marble.
• Eyjafjallajokull (E-15) volcano erupted on the 14th of April 2010 in South Iceland
• The ash from the E-15 volcano affected people in Europe as it stalled all flights and other modes of transport
• The E-15 eruption badly affected the freight industry - Kenya alone was said to be losing £2.4 million a day due to the E-15 eruption as their produce was being left to rot, 'premium' whiskey was not being transported and neither were medical drugs.