Tectonic Processes & Hazards Flashcards
What is a Divergent Plate boundary
Two plates moving away from each other. They are mostly in the sea & around mid-ocean ridges.
What is a Convergent Plate boundary
Where two plates move against each other. These actively form collision locations with plate material subducting into the mantle.
What is a Conservative Plate boundary
Where one plates slides against another. Movement is horizontal and lithosphere is neither created nor subducted.
What is the Lithosphere
Surface layer of Earth composed of the crust and upper mantle (100km deep on average). The lithosphere is broken into huge sections (tectonic plates)
Zone of Friction
As plates slide or move against each other this ‘zone of friction’ is created.
Passive continental margins
Where there if no collision or subduction taking place, and therefore tectonic activity is minimal here.
Characteristics of an Active Subduction zone
high magmatic activity, a narrow continental shelf with active seismicity.
What will happen between an oceanic plate and continental plate converging towards each other?
The oceanic plate will subduct underneath the oceanic plate creating a ‘subduction zone’ as its denser.
How may surface volcanism form at destructive plate boundaries?
volcanoes might appear at the ocean floor of Earth’s surface, typically appearing above the magma that forms directly above down-thrust plates.
What will happen between two continental plates converging towards each other?
Both plates move upwards creating ‘fold mountains’ such as the Himalayas.
What is a rift volcano
Created by two plates diverging from each other at the site of a mic-ocean ridge commonly. They tend to be less explosive and more effusive especially when in deep ocean.
What is a hotspot volcano
found away from boundaries of volcanoes but are fed by underlying mantle plumes that are unusually hot comparing with the surrounding mantle. (e.g. Hawaii).
Define the aesthenosphere
the upper layer of the earth’s mantle, below the lithosphere, in which there is relatively low resistance to plastic flow and convection is thought to occur.
What type of rocks generally make up oceanic and continental crusts?
continental crusts commonly are made up of granite, and oceanic crusts are primarily compose basalt.
What from the Earth’s core drives the creation of convection currents?
Radioactive decay in the core.
Seafloor spreading
The continuous input of magma at divergent plate boundaries, creating new crust. This commonly happens in mid-ocean ridges.
