tectonic hazards

• What are tectonic plates?

  Tectonic plates are huge floating slabs of the Earth's crust that are constantly moving on the semi-molten rock of the mantle.
• How is the Earth's surface separated?

  The Earth's surface is separated into tectonic plates.
• What are the two types of crust that make up tectonic plates?

  The two types of crust are continental crust, which is thicker (30-50 km) and less dense, and oceanic crust, which is thinner (5-10 km) and denser.
• What causes the movement of tectonic plates?

  Plates are moved by convection currents in the mantle.
• What are the places where tectonic plates meet called?

  The places where tectonic plates meet are called plate margins or boundaries.
• What are the three types of plate margins?

  The three types of plate margins are destructive margins, constructive margins, and conservative margins.
• What happens at destructive margins?

  At destructive margins, two plates are moving towards each other. An oceanic plate is forced under a continental plate, leading to the creation of ocean trenches and volcanic activity. When two continental plates meet, they form fold mountains.
• Provide an example of a destructive margin.

  An example of a destructive margin is along the west coast of South America, where the oceanic Nazca plate is subducted beneath the continental South American plate, creating the Atacama Trench.
• What happens at constructive margins?

  At constructive margins, two plates move away from each other. Magma rises from the mantle to fill the gap, creating new crust.
• Provide an example of a constructive margin.

  An example of a constructive margin is the movement of the Eurasian plate and the North American plate away from each other, forming the Mid-Atlantic Ridge.
• What happens at conservative margins?

  At conservative margins, two plates move sideways past each other or move in the same direction at different speeds. The crust is neither created nor destroyed.
• Provide an example of a conservative margin.

  An example of a conservative margin is the San Andreas Fault, where the Pacific plate is moving in the same direction as the North American plate but at a faster rate.
• What causes earthquakes at constructive margins?

  Tension builds along cracks in the plates as they move away from each other, causing an earthquake.
• What happens when an earthquake occurs?

  The plates jerk past each other, sending out shock waves. These vibrations are the earthquake.
• Where do volcanoes commonly occur?

  At destructive and constructive plate margins and sometimes over hotspots in the mantle, e.g. Hawaii.
• How do volcanoes form at destructive margins?

  The dense oceanic plate moves down into the mantle, melts, and forms a pool of magma. This magma rises through vents in the crust and erupts as lava, forming a volcano.
• How do volcanoes form at constructive margins?

  Magma rises up into the gap created by the plates moving apart, forming a volcano.
• What is a hotspot and how does it relate to volcanic activity?

  A hotspot is a part of the mantle that is extremely hot, causing magma to rise and form volcanoes.
• What is released during a volcanic eruption?

  When a volcano erupts it emits lava and gases. Some volcanoes also emit ash, which can cover land, block out the sun and form pyroclastic flows ( super heated currents of gas, ash and rock).
• Where do earthquakes occur?

  At all three types of plate margins.
• What causes earthquakes at destructive margins?

  Tension builds when one plate gets stuck as it moves past the other.
• What causes earthquakes at conservative margins?

  Tension builds up when plates that are grinding past each other get stuck, resulting in an earthquake.
• What is the focus of an earthquake?

  The focus is the point in the Earth where the earthquake starts, and the shock waves spread out from this point.
• What is the epicentre of an earthquake?

  The point on the Earth's surface directly above the focus.
• How are earthquakes measured?

  Using the moment magnitude scale which measured the amount of energy released.
• What is the nature of the moment magnitude scale?

  It is logarithmic, meaning a magnitude 7 earthquake causes ten times as much ground shaking as a magnitude 6 earthquake.
• What are the effects of different magnitudes of earthquakes?

  Earthquakes of magnitude 6 and below usually cause slight damage, while earthquakes of magnitude 7 and above can cause major damage and deaths.
• Can earthquakes occur away from plate margins?

  Yes, most earthquakes happen at plate margins, but a few can occur in the middle of tectonic plates.
• What magnitude was the New Zealand earthquake in 2016?

  7.8
• What were the primary effects of the New Zealand 2016 earthquake?

  • 2 people died and over 50 people were injured

  • Tens of thousands of homes were damaged and some were destroyed

  • 60 people needed emergency housing

  • Total cost of damage was around 8.5 billion dollars

  • Over 200 km of road and over 190 km of rail line was destroyed

  • Communications, water, sewage and power supplies were cut off
• What were the secondary effects of the New Zealand 2016 earthquake?

  • The earthquake triggered up to 100,000 landslides, which blocked major road and rail routes

  • A major landslide blocked the Clarence River, leading to flooding and the evacuation of 10 farms

  • The earthquake generated a tsunami with waves of around 5 m, leaving debris further inland.
• What was the magnitude of the Nepal earthquake in 2015?

  7.8
• What were the primary effects of the Nepal 2015 earthquake?

  • 9,000 people died and more than 22,000 were injured

  • 800,000 buildings were damaged or destroyed

  • 4 million people were left homeless

  • Cost of damage was over 5 billion dollars

  • Roads and bridges were destroyed

  • Water tanks and pipes were destroyed, leaving 2 million people without access to clean water and sanitation
• What were the secondary effects of the Nepal 2015 earthquake?

  • Triggered avalanches on Mount Everest which killed 18 people

  • Many mountain roads were blocked by landslides, preventing emergency aid from reaching remote areas

  • Lack of clean water caused outbreaks of typhus which killed 13 people