Conditions that influence the earthquake disaster risks

Question 1

MSLTEP

Magnitude

Answer 1

• The more seismic energy released, the higher the earthquake magnitude on the Richter scale, the more violent the shaking, the higher disaster risks as buildings are more likely to collapse, trapping people and leading to more injuries and loss of lives.

EXAMPLES
The strongest earthquake recorded is the earthquake in Valdivia, Chile in 1960 at a magnitude of 9.5.

Question 2

MSLTEP

Soil and rock properties

Answer 2

Seismic waves travel slower through loose, saturated soil and soft rocks and are amplified, shaking becomes more violent, soil liquefaction causes the ground to become unstable and flows like a liquid, buildings are more vulnerable to collapse.

EXAMPLES
During the 2011 Christchurch earthquake, the area also faced liquefaction as eastern sections of the city were built on a former swamp.

Question 3

MSLTEP

Level of preparedness

Answer 3

The more prepared the people are through evacuation drills and action plans, the lower the disaster risk as people have been trained to act swiftly

EXAMPLES
- Japan has been practicing emergency drills on September 1st to commemorate Disaster Prevention Day. This is done so that people are more mentally and physically prepared for an earthquake.

Question 4

MSLTEP

Time of shaking

Answer 4

• In the day, people are awake, more alert and able to evacuate to safety quickly, and less likely to be trapped, resulting in fewer injuries and deaths.

EXAMPLES
- In 1999 in the Sun Moon Lake region of Taiwan, an earthquake hit a few hours after midnight, causing 2400 deaths.

Question 5

MSLTEP

Distance from epicenter and depth of focus.

Answer 5

FOCUS
- Shallow-focus earthquakes, seismic waves take faster time to reach the surface and less energy would be lost, resulting in greater disaster risk and large damages. Buildings are more likely to collapse, trapping people and leading to more injuries and loss of lives. Vice Versa

EPICENTER
- The nearer an area is to the epicenter, the lesser the energy loss and absorption by rocks, the stronger the seismic waves, causing greater disaster risk and more violent shaking. Buildings are more likely to collapse, trapping people and leading to more injuries and loss of lives. Vice Versa

EXAMPLES
- In 2011, the Christchurch earthquake, the epicenter was just 10 km away with low magnitude caused great damage.

Question 6

MSLTEP

Population Density

Answer 6

The higher the population density, the more people and buildings exposed to earthquake shaking, the greater the disaster risk as more buildings are likely to collapse, trapping more people and leading to more injuries and loss of lives.

EXAMPLE
The 7.0 magnitude earthquake in Haiti in 2010 had a death toll of 300,000. Although much lower in magnitude than the 2011 Tohuku earthquake, the death toll was also significantly higher as the population density of Haiti is much higher.