1.1

• ​Divergent

  Divergent margins (constructive) are most clearly displayed at ocean ridges. 

  At these locations there are large numbers of shallow focus and generally low magnitude earthquake events. Most are submarine. 
• Convergent

  These are actively deforming collisions with plate material melting in the mantle, causing frequent earthquakes and volcanic eruptions.  
• ​Conservative

  Conservative (oblique-slip, sliding or transform) margins, where one plate slides against another. Here the relative movement is horizontal and classified as either sinistral (to the left) or dextral (to the right).

  Lithosphere is neither created nor subducted, and while conservative plate margins do not result in volcanic activity, they are sites of extensive shallow focus earthquakes, occasionally of considerable magnitude. 
• Plate boundary depends upon two factors:

  Motion - whether the plates are moving apart (divergent), colliding (convergent)  or sliding past each other, (conservative or transform).

  Plate type: whether the tectonic plates are oceanic or continental.
• Oceanic plates make up the ocean floor and are high density, basaltic rock, but only 7-10 km thick.
• Continental plates make up the Earth's landmasses and are much thicker at 25-70 km but made of less dense, granitic rock. 
• Intra-Plate Earthquakes

  Earthquakes can occur in mid-plate settings, usually associated with major ancient fault lines being reactivated by tectonic stresses.

  For instance, the New Madrid Seismic Zone on the Mississippi River generates earthquakes up to magnitude 7.5, but is thousands of miles from the nearest plate boundary. 
• Hotspot Volcanoes

  Some volcanic eruptions are 'intra-plate' meaning there are distant from a plate boundary at locations called mid-plate hotspots, such as Hawaii and the Galapagos Islands. 

  At these locations:

  Isolated plumes of convecting heat, called mantle plumes, rise towards the surface, generating basaltic volcanoes that tend to erupt continuously. 

  A mantle plume is stationary, but the tectonic plate above moves slowly over it. 

  Over millennia, this produces a chain of volcanic islands, with extinct ones most distant from the plume's location. 
• Mantle Plumes are concentrated areas of heat convection. At plate boundaries they are sheet-like, whereas at hot spots they are column like. 
• What is a hazard?

  A potential threat to human life or property
• What are the two types of natural hazards?

  Hydro-meteorological and geophysical
• Where do geophysical hazards occur?

  Near plate boundaries
• How do volcanoes distribute geographically?

  They are not evenly distributed or randomly patterned
• Where do volcanoes tend to be located?

  On the edge of continents and middle of oceans
• Which ocean do volcanoes surround?

  The Pacific Ocean
• Name two regions where volcanoes are found.

  Western America and East Africa
• What are earthquakes associated with?

  Plate margins
• Describe the distribution of earthquakes.

  They occur in large narrow belts on edges
• Where can some earthquakes occur?

  In the middle of oceans - mid-Ocean ridges
• Name a region known for earthquakes.

  Southern Europe/Asia
• What is the majority type of plate boundary?

  Divergent margins
• What happens at divergent margins?

  Plates move apart, creating new crust
• What occurs at convergent margins?

  Plates collide, causing earthquakes and eruptions
• Where can convergent margins be found?

  Across the Aleutian Islands and Japan
• What characterizes a continental collision zone?

  Where the African Plate meets the Eurasian Plate
• What is a characteristic of divergent margins?

  They are constructive and create new crust
• What type of earthquakes occur at divergent margins?

  Shallow focus and low magnitude
• What happens at convergent margins?

  Plate material melts in the mantle
• What is the movement at conservative margins?

  Horizontal sliding against each other
• What is the lithosphere's behavior at conservative margins?

  It is neither created nor subducted
• Where can intra-plate earthquakes occur?

  In mid-plate settings
• What is the New Madrid Seismic Zone?

  A zone generating earthquakes far from boundaries
• What is a characteristic of hotspot volcanoes?

  They are intra-plate and distant from boundaries
• What generates basaltic volcanoes at hotspots?

  Isolated plumes of convecting heat
• What is a mantle plume?

  A stationary area of heat rising
• How do mantle plumes affect volcanic islands?

  They create chains of islands over time
• What are the two factors that determine plate boundaries?

  Motion and plate type
• What are oceanic plates made of?

  High density, basaltic rock
• How thick are oceanic plates?

  7-10 km thick
• What are continental plates made of?

  Less dense, granite rock