Karteikarten
Geography - Earthquakes
Karten in diesem Stapel (38)
- 1What is a earthquake?Plate movement cause by friction and pressure building up then suddenly releasing. This causes seismic waves that travel through the plate to the surface
- 2What is the Focus?The point where the pressure is released. The ground ruptures at this spot, then seismic waves radiate outward in all directions.
- 3What is the epicenter?The point on the earth's surface vertically above the focus of an earthquake.
- 4Shallow earthquake?0-70km deep
These cause the most damage - 5Deep earthquake?300-700km deep
- 6Describe the Mexico City earthquake?Shallow Earthquake
1985
10,000 people died
50,000 injured
35% city destroyed - 7Describe the Iran earthquake?Shallow Earthquake
1990
35,000 died
100,000 injured
400,000 homeless - 8Describe the Tangshan earthquake?NOT associated with plate boundaries
1976
240,000 people killed
7.8 M initial quake, 7.1 M aftershock - 9Describe the Killari earthquake?Potentially caused by the building of a reservoir putting pressure on a fault
India, Killari
1993
10,000 people died - 10What are the Primary Hazards of earthquakes?Seismic waves - Magnitude and Frequency
Aftershocks - 11What is a seismic wave?a wave of energy that is generated by an earthquake that travels within the earth or along its surface causing buildings to collapse which kills
- 12What is the aftershock?a small earthquake or tremor that follows a major earthquake which causes further damage to already weakened buildings
- 13Secondary Hazards of an earthquake?Tsunamis
Landslides
Liquefaction
Flooding - sometimes caused by burst water pipes
Fire - caused by damaged gas+electrics - 14What is a Tsunami?Large sea waves generated by disturbance of the sea floor caused by earthquakes or submarine landslides.
eg. Indonesia, Dec 2004 - 15What is Liquefaction?Violent disruption of the ground causes it to become liquid-like due to increased pore water pressure which weakens the ground. Groundwater mixes with soil and comes through the newly formed cracks
eg. 1989 San Francisco - 16What are landslides and avalanches?When slope failure occurs due to ground shking
- 17What are the 3 types of seismic shock waves?P-waves
S-waves
Surface waves -> Love waves and Rayleigh waves - 18Whats a P-wave?Can travel through solids and liquids (mantle and core). The waves push and pull the earth in the same direction the earth is travelling. Fastest type of wave. High frequency.
- 19Whats a S-wave?Can travel through solids only (mantle only). The waves move the earth at 90* to the direction of travel. These waves cause a lot of damage because of their shearing effect.
- 20Whats a love wave?Can only travel through solids. They move the surface from side to side causing a lot of damage due to their shearing effect. Slowest waves.
- 21Whats a Rayleigh wave?Can travel through liquids and solids. They move the surface in a low frequency rolling motion radiating from the epicenter
- 22Define magnitude?Is the amount of energy released by the event and is usually measured on the Richter scale.
- 23Physical factors effecting an earthquake?Distance from epicenter
Depth of focus
Time of Day
Duration of shaking
Magnitude of earthquake
Geology of land - 24Human factors effecting an earthquake?Community preparedness
Emergency relief services
Economic + social structure of country
Building design
Gas and electricity supply
Land use planning - 25How do you prepare for an earthquake?Modify the event -> Controlling physical variables and hazard resistant design
Modify the vulnerability -> Prediction and Warning and community preparedness
Modify the loss - 26How do you modify the event -> Controlling physical variables?Geophysical event - it can NOT be stopped
Human induced earthquakes (eg. dam construction) could be prevented by consideration of the seismic hazard when siting the structure. - 27How do you modify the event -> Hazard-Resistant design?Aseismic designs
Not possible to rebuild whole cities
Economically developed nations and put in strict planning/building regulations - poor can't
Aseismic designs expensive to replace and repair after a quake - 28What are some aseismic designs?Concrete counterweight - moves in the opposite direction to quake, power failure means it cant move
Rubber shock absorbers - allows building to move with quake
Cross bracing - allows the tower to twist easier - 29Define modify the vulnerability?The aim is to lessen the impacts of the earthquake by prediction and warning, community preparedness and land use planning
- 30How do you modify the vulnerability -> Prediction and warning?Regional - use previous recorded data to pinpoint areas at risk (where)
'Gap theory' - predicts when a quake will happen based on how long the plates have been 'locked'
short term - changing water levels and released radon gas - 31How do you modify the vulnerability -> community preparedness?General public - must have supplies, move under protective furniture, await rescue, first-aid training valuable as 'self help only' period crucial
Emergency services - well organised, know where to deploy people in the area with disrupted transport routes and communication - 32Describe Tangshen earthquake?1976
250,000 people died + 160,000 injured
16% above due to trying to escape
25% above due to heat, thirst + hunger
Further 250,000 tried rescuing others
Most survivors were under heavy furniture - 33Whats a tsunami?Giant waves caused by earthquakes under the sea. Out in the depths of the ocean, tsunami waves do not dramatically increase in height. But as the waves travel inland, they build up to higher and higher heights as the depth of the ocean decreases.
- 34Describe a tsunami wave in open ocean?Very deep water
High speed - 700km/h
long wavelength - 200km
small amplitude - 1m - 35Describe a tsunami wave closer to land?Shallower water
Waves compress = energy more concentrated
slower - 80km/h
wavelength decreases - 20km
amplitude increases - many meters - 36Hydrostatic effect?Debris in the water that kills being moved by the water
- 37Hydrodynaimc effect?power in the wave destroying buildings and infastructure
- 38Describe the Indonesian tsunami?9.1 magnitude quake
Sunda trench off SW coast Indonesia
Australia plate subducted under Burma plate
20m slip along 1600km faultline
epicenter 160kn offshore - focus 30km down
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- A Level Geography Karteikarten am Geography - Earthquakes, erstellt von Sydney Routley am 04/04/2015.
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