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Geography Gr 6 > Earthquakes > Flashcards

Flashcards in Earthquakes Deck (23):
1

What is a earthquake 

Shaking of the surface of Earth because of sudden release of energy

2

What does an earthquake create

Seismic waves

3

What can an earthquake range in

Range in size

4

What is a hypocentre

Point of initial rupture called its focus or hypocentre

5

What is a epicentre

Point on ground level, directly above hypocentre

6

What can earthquakes cause (3)

  • In ocean causes tunami
  • landslides  
  • volcanoes

7

Most earthquakes happen in a certain ... (3)

  • sequence
  • location and
  • time

8

What are earthquake clusters

Small tremors that does no or little damage

9

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

10

How many earthquakes per year and how many can be felt

500 000 and only 100 000 can be felt

11

Why do seismic stations register more E-quakes?

bc of improve instrumentation

12

Where does most E-quakes take place (3)

40 000 km long horseshoe shape zone = pacific ring of fire

13

What are the effects of an E-quake?

  • shaking and ground rupture
  • landslide/avalanches
  • fire
  • tsunamis
  • floods

14

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

15

Explain Landslides and Avalanches with E-quakes

Landslides are when Slope instability happens when E-quakes Servere storms Volcanos Big waves Wild Fires

16

Why do emergency personnel face problems during landslides and avalanches

Because trying to rescue people is dangerous because instability of the area.

17

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

18

In which E-quake did more people die of fire than the E-quake?

1906 San Fransisco E-quake

19

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

20

Why does Tsunamis happen

Because e-Quake happens in crust below ocean

21

Why is Tsunamis so dangerous

It destroys every thing in its path, harbours, coastal cities buildings farms ect.

22

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

23

What can cause floods

E-quakes that break dam walls

E-quake that change direction of a river