Chapter 1 - Locations At Risk From Tectonic Hazards Flashcards
Seismic hazards
Generated when rocks in the earths surface come under stress so they break and become displaced
Volcanic hazards
Associated with eruption events
Intra-plate earthquakes
These occur in the middle or interior of tectonic plates, rarer than boundary earthquakes
Volcano
Landform that develops around a weakness in the earths crust from which molten magma, volcanic rock and gases are ejected or extruded
Divergent boundary
- constructive
- mid-ocean ridges
- large numbers of shallow focus and low magnitude earthquakes
- most are submarine
Convergent boundary
- plates are moving together
- actively deforming collision locations
- plate material melts in the mantle
- frequent earthquakes & volcanoes.
Lithosphere
- surface layer of the earth, rigid outer layer composed of the crust and upper mantle.
- very thick
- always moving, but very slowly, fuelled by rising heat from mantle, creates convection currents
- broken into huge sections which is tectonic plates
Plate tectonics
Theory developed to explain large scale movements of the lithosphere.
Volcanic hotspot
Area in the mantle from which heat rises as a hot thermal plume from deep in the earth.
Paleomagnetism
Results from the zone of magma locking in or striking the Earth’s magnetic polarity when it cools. Can be used to create a geo timeline
Benioff zone
An area of seismicity corresponding with the slab being thrust downwards in a subduction zone
Locked fault
A fault that is not slipping because the frictional resistance on the fault is greater than the shear stress across the fault, so it’s stuck
Hypocentre
The focus point within the ground where the strain energy of the earthquake stored in the rock is first released.
Soil liquefaction
The process by which water-saturated material can temporarily lose normal strength and behave like a liquid under the pressure of strong shaking
Intensity
A measure of the ground shaking. Ground shaking is what causes building damage and deaths.
