1. LOCATIONS AT RISK FROM TECTONIC HAZARDS Flashcards
what do tectonic hazards include? (3 marks)
-earthquakes
-volcanic eruptions
-tsunamis
tectonic hazards can be classified as either…
-seismic
-volcanic
what is a seismic hazard?
-generated when rocks within 700km of the earth’s surface come under stress so they buckle and become displaced
what is a volcanic hazard?
-associated with eruption events
where are scattered earthquakes usually found?
-found in continental interiors
-around olf fault lines
what is a volcano?
-Land form that develops around the weakness in earths crust from which molten magma, volcanic rock and gases are ejected.
how many active volcanoes are there in the world?
500
where are volcanoes found? (3 marks)
-divergent plate margins
-convergent plate margins
-hotpots
what is volcano violence determined by?
-amount of dissolved gases in magma
what is the oceanic fracture zone?
-belt of activity through oceans along mid-ocean ridges
What’s the continental fracture zone?
-follows the mountain ranges from Spain
where do tsunamis occur?
90% occur within the Pacific basin
what is a plate margin?
-areas adjacent to plate boundaries
divergent (4 marks)
-plates move apart
-mostly displayed at mid-ocean ridges
-large numbers of shallow focus
-low-magnitude earthquakes
convergent (3 marks)
-plates move towards each other
-cause frequent earthquakes and volcanoes
-plate material melts in the mantle
conservative (2 marks)
-plates slide past each other
-horizontal movement, classified as sinistral (left) or dextral (right).
what is the lithosphere?
-rigid outer part of the earth, consisting of the crust and upper mantle
order of risk of divergent, conservative and convergent plates…
- convergent
- conservative
- divergent
what is a tectonic hazard?
-a threat to humans and infrastructure as a result of tectonic plate processes and movement
where are most earthquakes found?
-on plate boundaries
where are most powerful earthquakes found?
-conservative margins
what does intra-plate mean?
-earthquakes that occur inside the plate boundaries due to stress occurring in the crust
