EARTHQUAKE Term 3 Flashcards
What is a earthquake
Shaking of the surface of Earth because of sudden release of energy
What does an earthquake create
Seismic waves
What can an earthquake range in
Range in size
What is a hypocentre
Point of initial rupture called its focus or hypocentre
What is a epicentre
Point on ground level, directly above hypocentre
What can earthquakes cause (3)
* In ocean causes tunami
* landslides
* volcanoes
Most earthquakes happen in a certain … (3)
* sequence
* location and
* time
What are earthquake clusters
Small tremors that does no or little damage
What is an aftershock (4)
* earthquake that happen after previous earthquake/main shock
* same region as main shock but smaller scale
* plates settle after main shock and causes aftershock
How many earthquakes per year and how many can be felt
500 000 and only 100 000 can be felt
Why do seismic stations register more E-quakes?
bc of improve instrumentation
Where does most E-quakes take place (3)
40 000 km long horseshoe shape zone = pacific ring of fire
What are the effects of an E-quake?
* shaking and ground rupture
* landslide/avalanches
* fire
* tsunamis
* floods
Explain shaking and ground rupture (4)
Main effect of E-quake = damage of building/infastructure Damage depens on:
* Magnatude
* Distance of Epicentre
* Topography of land
Explain Landslides and Avalanches with E-quakes
Landslides are when Slope instability happens whenE-quakesServere stormsVolcanosBig wavesWild Fires
Why do emergency personnel face problems during landslides and avalanches
Because trying to rescue people is dangerous because instability of the area.
Discuss fire caused by E-quakes
Fires start because E-quakes damage electrical and gas lines
Stopping fires are difficult as water lines are damaged
In which E-quake did more people die of fire than the E-quake?
1906 San Fransisco E-quake
Discuss Tsunamis during E-quakes
* Tsunamis are long waves created by sudden movement of large volumes of water
* Travel at 600 - 800 km p hour
* Distance between wave crest 100 km
* This wave period vary from 5 min to 1 hour
Why does Tsunamis happen
Because e-Quake happens in crust below ocean
Why is Tsunamis so dangerous
It destroys every thing in its path, harbours, coastal cities buildings farms ect.
What is a flood
When a dam or river overflows because the water is more than what the dam of river can hold.
Water now flows where the land used to be dry
What can cause floods
E-quakes that break dam walls
E-quake that change direction of a river
