Earthquakes

Question 1

Shallow vs deep

Answer 1

Shallow
-0-70km deep.
-on all plate boundaries.
-evidence that lithosphere is divided into plates.
-stronger ground shaking at surface concentrates in one areas
-Pakistan 2005, 23km deep, 7.5 magnitude and over 80,000 died.

Deep
-70-700km deep.
-on destructive plate boundaries.
-evidence for subduction.
-focus is deep so less ground shaking, shaking over a wider area due to seismic waves spread out.
-Afghanistan 2015, 212km deep, 7.5 magnitude and 400 deaths.

Question 2

Magnitude and intensity

Answer 2

M- is the energy released
I- is the amount of ground shaking in a specific location, 4 factors:
-magnitude.
-distance from epicentre and focus.
-rock and soil characteristics.
-resistance of buildings/infrastructure to ground shaking.

Question 3

Waves in an earthquake

Answer 3

Primary waves - compression waves move fast through solid liquid and epicentre and start the earthquake.
Secondary waves- also start the earthquake but half the speed and only travel through solids e.g the crust.
Surface waves- in result of an earthquake they can travel vertically or at a tight angle.

Question 4

Scales

Answer 4

Magnitude
Richter scale- uses sister to measure energy released and logarithmics to measure the range in size.
+widely known and understood in the media, measure energy released with no upper limit (adaptable.)
-was designed for San Andreas fault one doesn’t take into account damage.
Moment magnitude- uses diameter and logarithmic again but also uses other parameters to see rock strength.
+takes into other factors such as rock type.
-not as accepted in media so less understood.
Intensity
Mercalli scale- uses 12 point scale and qualitative data to measure ground shaking and damage to buildings.
+info on direct impact on social aspects.
-subjective and bias due to opinion based.

Question 5

Hazards earthquakes generate

Answer 5

Primary - ground shaking- vertical or horizontal and intensity depends on magnitude and distance from epicentre.
Secondary - landslides or mass movement, shaking triggers mass movement e.g Nepal 2015, over 20,000 land slides.
Secondary-flooding- indirectly through triggering tsunamis and destroying dams can create ‘quake lakes.’

Question 6

Impacts of people near earthquakes

Answer 6

Haiti ( LIDC ) - located along boundaries of Caribbean and North American plate and faults. Most effects due to primary ground shaking.
Japan ( AC ) - located on 4 plate boundaries and subduction zones. Most effects from secondary impacts of tsunamis.

Why?
-cheaper to stay than move.
-successful mitigation, only 2 have died from living near sukarjima in Japan.

Haiti
People- 2010 EQ, Magnitude 7 and 300,000 died and 1.5 million displaced.
-UN peacekeepers tried to help with relief efforts however led to cholera outbreak , 10,000 died.
-second quake in 2021, 7.2 magnitude, 2,000 died.
Economy
-$7.8 billion loss.
-housing market affected and small farmers left bankrupt accelerating rural-urban migration.
-relied on US to subsidise and import rice.
Environmental
-infrastructure
-medical wastage from emerging responses.
-severely damaged capital of Haiti.
Political
-law suit filed against UN for cholera outbreak and people still awaiting compensation in 2020.

Japan
People- 2011, 16,000 died.
-young and elderly most affected with every young person ether losing a teacher or parent.
-mass mortality and destroying or crematoria led to mass grave stones.
Economic
-gov injected 200 billion yen into economy.
Environment
-infrastructure.
-4ports closed.
-flooding of farms.