Hazards - definitions Flashcards
What is acid rain?
Acidic precipitation that has negative impacts on natural ecosystems and is associated with air pollution.
What is coastal flooding?
Dry and low-lying land is submerged by seawater.
What are convection currents?
The circular motions of upper mantle layers responsible for sea floor spreading and driven by upwelling mantle material.
What is gravitational sliding?
The movement of tectonic plates as a result of gravity.
What is an island arc?
A linear chain of volcanic islands associated with an ocean trench where subduction is taking place.
What is a lava flow?
Molten rock flowing on the surface. Acidic lava tends to be more viscous and solidifies nearer to source than basaltic lava which generally flows over greater distance before solidifying.
What is liquefaction?
Loosely packed, water-logged sediments at or near the ground surface lose cohesion and behave as a liquid rather than a solid because of shaking during an earthquake.
What is the lithosphere?
The crust and upper mantle that form the outermost solid layers of the Earth.
What is a magma plume?
A rising column of hot rock in the mantle.
What is magnitude?
The overall strength or ‘size’ of a hazard.
What is a mudflow (lahar)?
A mix of volcanic ash and rainwater or meltwater that travels downslope.
What is a multi-hazardous environment?
An environment prone to experiencing combinations of seismic, volcanic, atmospheric or wildfire hazard.
What are nuées ardentes (pyroclastic flows)?
Dense, fast-moving flows of hot gas (over 800 °C) and rocks that move rapidly downslope at speeds over 700 km/hr.
What is pyroclastic and ash fallout?
Airborne particles of varying sizes that have been ejected from volcanic vents into the atmosphere before falling to the surface.
What is ridge push?
A driving force for the movement of tectonic plates that occurs at mid-ocean ridges as a result of gravitational forces causing downward movement away from the ridge.
What is a rift valley?
A steep sided valley formed by the downward displacement of crust due to separation of tectonic plates.
What is sea-floor spreading?
The formation of a new oceanic crust which occurs through the upwelling of magma at mid-ocean ridges and its outward movement from such ridges.
What is seismicity?
The processes associated with earthquakes in a given area. The frequency and intensity of such processes.
What is a shockwave?
A wave of energy spreading outward from the focus of an earthquake.
What is slab pull?
A driving force for the movement of tectonic plates occurring at subduction zones as a result of sinking of the crust there.
What is a storm surge?
A temporary, localised rise in sea level as a result of atmospheric pressure changes and storm wind direction.
What is tephra?
Rock fragments and particles, eg pyroclastic material, ejected during a volcanic eruption and subsequently deposited on the earth’s surface.
What is a tsunami?
One or more high magnitude sea waves caused by an earthquake or other offshore underwater disturbance such as slippage of submarine slopes.
What is vulcanicity?
The processes associated with active volcanoes in a given area. The frequency and intensity of such processes.
What is a wildfire?
An uncontrolled fire occurring in open country or wilderness regions.
