Effects of Earthquake Activity

Question 1

Ground Deformation

Answer 1

CAUSE: Ground surface above earthquake is distorted and displaced, moving vertically/horizontally. Confined closely to epicentre usually but could occur several kilometres along fault.

IMPACT: Alaska 1964 lifted land surface by an average of 2m

Question 2

Seismic shaking

Answer 2

CAUSE: Seismic energy released by an eathquake radiates out from focal point. Shake the crust as they pass through via lateral shear motion.

IMPACT: 1989 San Franciso earthquake, 1km of Nimitz Highway collapses. dozens of cars crushed and 50 lives lost.

Question 3

Landslides

Answer 3

CAUSE: Earthquake acts as trigger mechanism starting movement of material down steep slopes

IMPACT: Central China 1976 landslide 250,000 people in epicentre, itself in a mountainous region

Question 4

Liquefaction

Answer 4

.CAUSE: Soft or unconsolidated sediments amplify shaking. Most prominent in areas of significant water content. Shaking sediment acts as a liquid causing building foundations to subside.

IMPACT: Kobe 1995 7.5 quake causes liquifaction that destroys the world’s largest container port in 20 seconds

Question 5

Fire

Answer 5

CAUSE: Seismic shaking may break gas lines and sever electricity cables, causing fires.

IMPACT: 1906 San Francisco 500 city blocks burnt down

Question 6

Flood

Answer 6

CAUSE: Water pipelines, collapsed dams and damaged river levees may all cause flooding.

IMPACTS: Tajikistan’s Usoi Dam was created by an earthquake; another earthquake could destroy it and kill 5 million people by floods.

Question 7

Tsunami

Answer 7

CAUSE: Seismic waves underwater.

IMPACTS: 2004 Boxing Day Tsunami 30m high kills 250,000 people in 14 countries and displaces 1m