Tectonic Hazards Flashcards
What are the x4 processes that drive tectonic plate movement?
- Mantle Convection
- Sea floor spreading
- Slab pull
- Subduction
What are the causes of Intra-plate earthquakes?
Ancient fault lines being re-activated by tectonic stresses
Process of convection currents?
As tectonic plates move pressure builds. Hot magma produced from radioactive decay pushes up from the mantle to the earth’s crust which erupts. Lava then cools and forms rock.
What hazard occurs and what direction happens at divergent plate boundaries?
Divergent plates move away from each other which causes shield volcanoes
What plate boundary has the most explosive volcanoes?
Convergent has more silica which makes it more viscous (sticky)
What is the Benioff Zone?
Where the Oceanic plate subducts under the continental plate
What are volcanic hotspots?
An area on the Earth that exists over an isolated magma plume (concentrated heat in an area) in the upper mantle
What are intraplate earthquakes?
Occur in the middle of plates , far from the margins
X3 different types of seismic wave?
Love - L
Primary - P
Secondary - S
Characteristics of P waves?
Body waves. Fastest and first to reach surface, shakes in a backward and forward motion. Least damaging.
Characteristics of L waves?
Surface wave. Slowest, shakes ground side to side. Most damaging
Characteristics of S waves?
Body waves. Slower, shakes at the direction of travel. (sideways) More damaging than P waves.
Are earthquakes or volcanic eruptions easier to predict and why?
Volcanic eruptions. Lot more warning signs. E.g ground tremors and gas emissions (sulphur dioxide)
What is Slab pull?
Newly formed oceanic crust at mid-ocean ridges, becomes denser and thicker as it cools. Sinks into the mantle under it’s own weight.
What is subduction?
The Earth isn’t expanding because new crust is being created in once place and being destroyed in another
