Seismic Hazard - 3.1.5.4 Flashcards
(38 cards)
Earthquake
A sudden release of energy in the earth’s crust is caused by the build-up of pressure.
Focus
Where the earthquake started underneath the surface.
Epicentre
The point on the ground is directly above the focus. The earthquake is the most destructive here.
Seismometer
An instrument which measures shock waves of an earthquake.
Benioff Zone
When earthquakes get progressively deeper with distance from the subduction zone.
Richter Scale
A logarithmic scale is used to determine the strength (magnitude) of an earthquake.
Mercalli Scale
A descriptive scale used to measure the intensity of earthquakes
Primary effect
Something caused directly by the hazard and happens immediately.
Secondary effect
Something caused indirectly by the hazard (due to the primary effects) and happens after the event.
Secondary hazard
A hazard is caused by the primary hazard and happens after the event i.e… a tsunami is created by an earthquake.
Fukushima
The name of the power station which overheated exploded and released radiation.
Tsunami
A seismic sea wave is caused by the displacement of a large volume of water above or below the surface.
Liquefaction
When soil or loose sediment loses its strength and stiffness by the shaking caused by earthquakes.
Geology
The science of the rocks - which can have massive implications on the impacts of earthquakes.
Landslide
The movement of a mass of rock, debris, or earth down a slope.
Cholera
An infectious disease carried in contaminated drinking water. It causes diarrhoea and was responsible for 7,000 deaths in Haiti.
Retrofitting
To add reinforcement to buildings and infrastructure which it did not have when it was made
Building regulations
Structures must meet strict guidelines set by the government to be declared earthquake-proof.
Foreshocks
The movement plates make before a big earthquake. Can be used as a warning sign.
Seismic Gap Theory
A way of calculating the probability of an earthquake is by measuring the recurrence period (times between big earthquakes).
Radon Gas
A gas which escapes from the crust before an earthquake. Can be used as a warning sign.
Earthquake Early Warning System
A device which detects an earthquake’s primary waves (fastest seismic wave) and alerts people that the more powerful and destructive secondary waves are on their way (60% slower).
Tsunami Alarm
A device which alerts people by the coast that a tsunami is on its way.
Earthquake-proof buildings.
Name of buildings in Japan which have met strict building regulations (i.e. deep foundations, reinforced steel and counterweights).
