Earthquakes Flashcards
Where are the main earthquake zones
Clustered along plate boundaries
What does e/q mean
EARTHQUAKE
Which plate boundaries are associated with e/q
Conservative and destructive boundaries — but can occur at all boundaries
Why might an earthquake occur within the plates (intra-plate)
Due to ancient faults which solid crust cracks over millions of years
How are earthquakes created within the destructive plate boundaries
any plate boundary stress and strain can build up along the joint, due to friction created by masses of rock trying to move past each other.
This is greatest along the wadati-benioff zone within destructive plate boundaries
conservative boundary earthquake characteristic
sliding
no volcanoes
earthquakes are violent
no crust is made or destroyed
Stress is also great along transform (conservative) boundaries
what is a focus of an earthquake
the point of which the strain is released this sends earthquake (seismic)
what is the epicentre of an earthquake
waves in all directions being the strongest at the point on the earth’s surface directly above the focus
What are the 4 earthquake waves
P waves - primary waves
S waves - secondary waves
Love waves
Rayleigh waves
What is a P wave
primary wave
Body wave (go through the earth)
They are the fastest and first to reach the surface
Travel through both solid and liquids
Only damaging in the most powerful earthquakes
What is a S wave + its characteristics
secondary wave
slower than a P wave (by 60%)
Only travel through solid
they do more damage than P wave
what is a L wave
Love wave
the slowest (last to arrive)
cause the most shaking (from side to side)
they are larger and focus all their energy on the surface
cause the most damage
TRUE OR FALSE:
is Rayleigh wave a surface wave
TRUE
what two characteristics do scientists use to measure earthquakes
magnitude and intensity
what does magnitude measure
the amount of energy released at the epicentre.
what does intensity measure
An earthquakes effect on people, infrastructure and the natural environment
what scale is used to measure magnitude
MMS (moment magnitude scale)
one to infinite - generally stops at 10
logarithmic scale
e.g 9.5 in chile 1960
what scale is used to measure intensity of e/q
the modified Mercalli intensity scale
scale of 1 (hardly noticeable) to X (catastrophic)
What does MMS use to calculate rating
Size of seismic waves
Amount of slippage or rock movement
Area of the faults surface broken by the e/q
Resistance of the affected rocks
The physical effects of an earthquake
Magnitude
Depth
Distance from the epicenter
The human effects of an earthquake
-Countries level of development
-Population
-Level of preparedness
-Effectiveness of emergency responses
-Impact of indirect hazards (fire and landslides
Define a primary effect for e/q
those that happen as a direct result of an earthquake
Define secondary effect for e/q
those that happen after the initial shaking
What is a primary effect of an earthquake
Ground shaking – which causes building, bridges roads and infrastructure to collapse – killing and injuring those nearby
Crustal fracturing – when the energy released during the earthquake causes the Earth’s crust to crack
What is a secondary effects of an earthquake
-Liquefaction
-Landslides and avalanches
-Tsunami
What is liquefaction
The violent shaking causes surface rocks to lose strength and become more liquid than solid.
How can liquefaction effect
It can make rescue efforts more difficult and also disrupt underground power and gas lines (leading to fires)
when do landslides occur
when e/q’s loosen loose rocks and unconsolidated material on steep slopes causing material to move downwards, influenced by gravity
what can landslides lead to in regards to people
landslides may hit small settlements within its topography and…
-block or destroy roads and railways
-making it difficult to rescue people or supply emergency aid and rebuilding materials
example of landslides
Nepal 2015, Kashmir 2005
