Earthquakes

Question 1

Give an example of tectonic processes that caused an Earthquake?
JAPAN CASE STUDY

Answer 1

TOHOKU Earthquake and Tsunami
Cataclysm (natural disaster) that moved the earth 10 inches off its axis

The unlucky port of Sendai which was only 80 miles from the 8.9 magnitude earthquake was hit badly.
Storm surge went 6 km up into the land around the port- over an 18ft sea wall

Question 2

What are earthquakes?

Answer 2

Movements within the Earth’s crust that can cause stress to build up at points of weakness, causing rocks to become deformed
When stress finally exceeds the strength of the rock, the rock fractures along a fault, often at a zone of existing weakness
Stored energy is suddenly released as an earthquake= INTENSE VIBRATIONS
=MAKE THE GROUND SHAKE

Question 3

How do we measure earthquakes/PREDICT? (experimental)

Answer 3

Foreshocks- increased seismicity before an eruption
Unusual Animal Behaviour- Stanford Research Institute- “Project Earthquake Watch= watching 70 animal species along the San Andreas Fault

Hydro chemical Variation
Temperature Change
Water Level variations
Radon Gas production

Question 4

How do we measure earthquakes (main)?

Answer 4

The Richter Scale-MAGNITUDE

• Logarithmic
• No limit

The Moment Magnitude Scale

• Logarithmic
• No limit
• More accurate than Richter

The Mercalli Scale

• Based on Observations- pictures, videos, reports
• 1-12 -12= mass/ total destruction

Question 5

Differentiate between P and S waves?

Answer 5

P= Primary, Longitudinal, Solid and Liquid

S= Secondary, Transverse, just Liquid= stopped by the earths liquid core

Question 6

What Seismic hazards do earthquakes cause?

Answer 6

TSUNAMI= large waves caused by the displacement of large volumes of water
Can be triggered by underwater earthquakes

LANDSLIDES/ AVALANCHES- ground movements= water can infiltrate = trigger a landslide

SOIL LIQUIDIFICATION- vibrations of the earth can cause it to act like a liquid- soil is easier to DEFROM and SUBSIDE
eg: Alaska Earthquake of 1964- beneath Turnagain Heights Alaska

Question 7

What are Primary Seismic effects?

Answer 7

Ground shaking from foreshocks and the eruption

Ground RUPTURES= visible breaking of the earths surface along a fault

Question 8

What affects the magnitude of an earthquake?

Answer 8

MARGIN TYPE- destructive, subduction zones= harder to mitigate and a greater increase in pressure

RATE OF MOVEMENT- tectonic plates move in relation to each other at different rates (1-15cm per year)

DEPTH OF FOCUS- can be close to/ far from the earths surface
a DEEP FOCUS= increased magnitude but less damage as further from the epicentre

Question 9

EARTHQUAKE CASE STUDY?

Answer 9

Kashmir Earthquake - 8th OCTOBER, 2005

• North Pakistan
• Destructive Plate margin= Indian and Eurasian Plate meet at a subduction zone
• 7.6 on the Moment Magnitude Scale (MMS)
• Caused damage to an area of 30,000 km
• nearly 1000 aftershocks after the event

Question 10

Impacts of the Kashmir Earthquake?

Answer 10

-SOCIAL= 80,000 people died
3 million were made homeless
water pipes and electricity lines were broken

-ECONOMIC= 5billion dollars in damage
thousands of buildings destroyed, an estimated 3.5 million cost of rebuilding

-ENVIRONMENT= landslides and rockfalls occurred through the region
a landslide in Jhelum valley= 2km long

Question 11

Responses of the Kashmir Eruption?

Answer 11

The Pakistani Government set up the Earthquake Reconstruction and Rehabilitation Authority (ERRA) to coordinate activities with institutions
40,000 people relocated to a new town
Government support for those unable to rebuild on their own