12. EQ: factors affecting damage of EQ

Question 1

distance from EQ

Answer 1

• closer to epicenter –> more damage
• energy from seismic waves strongest @ epicenter, reduce intensity away from epicenter
• e.g. 2011 EQ in Christchurch NZ, epicenter in town few km away from city center, city center suffered greatest damage

Question 2

time of occurrence

Answer 2

• time affects locations + current activity
• sleeping –> higher chance of trapped in house –> more deaths
• e.g. more than 2400 people died in EQ occurring couple hours after midnight in Sun Moon Lake Region in Taiwan 1999

Question 3

magnitude of EQ

Answer 3

• higher magnitude on richter scale –> more damage caused
• impact of EQ 10x greater than previous one on scale
• e.g. 2011 Tohoku EQ had magnitude of 9.0 –> death toll of 28 000 people`

Question 4

population density

Answer 4

• more density build up –> worsen devastation –> more casualties & damage than EQ at less dense areas

Question 5

soil type

Answer 5

• sediments loose & unconsolidated –> seismic waves amplified –> greater damage when EQ occurs
• structures built on saturated & unconsolidated sediments affected by liquefaction
• e.g. Christchurch in NZ, many houses & buildings abandoned because of liquefaction after EQ in 2011

Question 6

level of preparedness

Answer 6

• preparations: evacuation plans, trained rescue workers, range of action plans
• damage more manageable when people are planned