Tectonics :) Flashcards
What is the lithosphere
the rigid outer part of the earth, consisting of the crust and upper mantle.
What is the asthenosphere
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 are convection currents
Convection currents describe the rising, spreading, and sinking of gas, liquid, or molten material caused by the application of heat. They move the tectonic plates
Describe the structure of the earths layers
The earth is made up of three different layers: the crust, the mantle and the outer and inner core
Describe the different crusts
- Oceanic crust
(5-10km thick, dense) - Continental crust
(20-70km thick, less dense)
Describe what the mantle is
the region of the earth’s interior between the crust and the core, believed to consist of hot, dense silicate rocks
Describe what the inner and outer cores are like.
The inner core is under intense pressure, which keeps it solid despite high temperatures. Outer Core. The outer core, which is liquid, is about 1300 miles (2092 km) thick.
What are the three different types of plate boundary?
- Destructive
(plates moving into each other) (volcano) - Conservative
(slipping past each other) (faults) - Divergent
(moving away from each other) (rift valleys)
Explain what a rift valley is
A rift valley is a lowland region that forms where Earth’s tectonic plates move apart
What is a subduction zone
a region in which a portion of a tectonic plate sinks beneath another plate into the Earth’s interior. oceanic under continental
what is slab pull
the force due to the weight of the cold, dense sinking tectonic plate. helps pull down the oceanic plate under the continental plate
What is ridge push
magma rises as the plates move apart. The magma cools to form new plate material. As it cools It becomes denser and slides down away from the ridge. This causes other plates to move away from each other.
what is palaeomagnetism
Palaeomagnetism is the study of the Earth’s magnetic field preserved in rocks. The discovery that some minerals, at the time of their formation, can become magnetised parallel to the Earth’s magnetic field
What is the evidence for plate tectonics
- South America and Africa would fit nicely together
-Fossils of animals on one continent found on another continent (mesosaurus) - Coal found in Antarctica and UK (can only be made in tropical conditions)
describe the distribution of earthquakes and volcanos
tend to follow patterns around the plate boundaries apart from hotspots like Hawaii.
How do we measure earthquakes
with seismograph and with the richter scale (1-10)
how do we measure volcanos
with the volcanic explosivity index (VEI)
What are the primary effects of earthquakes
Primary effects of an earthquake can include the ground shaking, buildings collapsing, and the ground splitting
What are the secondary effects of an earthquake
ground settlement, lateral ground displacement, liquefaction, landslides and rock falls, tsunamis, floods, fires and falling debris.
describe liquefaction
Liquefaction takes place when loosely packed, water-logged sediments at or near the ground surface lose their strength in response to strong ground shaking. The buildings tend to sink/collapse
What are the different types of volcano
- composite
(The lava of a composite volcano is acidic and is of high viscosity, calmer) - shield
(The basaltic lava of a shield volcano is runny and is of low viscosity, violent) - cinder cones
(violent lava) - lava domes
(viscous lava calmer)
Primary effects of volcanic eruptions
Pyroclastic Flows, Lava Flows, Volcanic Bombs and Tephra, Lahars
secondary effect of volcanic eruptions
Widespread ash-fall or gas impact (acid rain) may lead to agricultural hardships including crop failure, loss of livestock and contamination of water supplies which, in turn, may trigger famine and related diseases.
what is a lahar
A lahar is a destructive mudflow or debris flow composed of a mixture of volcanic ash, rocks, and water.
