Earthquakes

Question 1

Extent : Magnitude

Answer 1

Magnitude : the greater the magnitude, the more damage done to a place
Magnitude refers to the amount of energy released from an earthquake
It is measured using the Richter scale.
The energy released causes the ground to shake, and that causes buildings and infrastructure to be damaged and collapse.

Question 2

Extent : Magnitude - example

Answer 2

Example:
The 2004 Indian Ocean earthquake had a magnitude of 9.0 and killed over 200 000 people and caused countless buildings to be damaged and destroyed.

Question 3

Extent : Population Density

Answer 3

Population density : the greater the population density, the more damage there will be
Areas with a high population density will tend to suffer more casualties than areas with fewer people because more people are exposed to the dangers from the earthquake.

Question 4

Extent : Population Density - example

Answer 4

Example:
The 2004 Indian Ocean earthquake hit densely-populated areas, and even popular tourist destinations and killed over 200 000 people.

Question 5

Extent : Distance From Epicenter

Answer 5

Distance from epicenter : the smaller the distance from epicenter, the more damage done
Distance from the epicenter determines how strong the seismic waves are when they reach an area.
Places further away from the epicenter would experience less shaking because energy is lost as it travels through the ground. Thus, less damage is done.
On the other hand, places nearer the epicenter would experience more shaking because there is still a lot of energy released from the earthquake, leading to greater shaking.

Question 6

Extent : Distance from epicenter - example

Answer 6

Example:
The 2010 Haiti Earthquake (magnitude 7) had an epicenter that was near (16km) from the capital.
As a result the capital was almost completely destroyed with over 200 000 dead.

Question 7

Extent : Time of occurrence

Answer 7

Time of occurrence : when earthquake occurs at a time when people are not alert/awake, the more damage (more deaths) there will be
The time of day when an earthquake happens determines where people are and what they are doing. This affects their chances of survival during an earthquake.
More deaths occur when people are not alert or awake to react and get to safety during an earthquake

Question 8

Extent : Time of occurrence - example

Answer 8

Example:

The 1995 Kobe earthquake hit at 5.46 am. Many people were still asleep and caused a death toll of 6400.

Question 9

Extent : Preparedness of People

Answer 9

Preparedness of people : the less prepared people are for an earthquake, the more damage (deaths) there will be.
More deaths occur when people are not prepared for an earthquake
People would not know what to do or where to go during an earthquake
If they panic, they may endanger themselves and others even more with irrational behaviour

Question 10

Extent : Preparedness of People - example

Answer 10

Example:
The 2010 Haiti earthquake had a death toll of about 300 000. Haiti has not been hit by an earthquake since the 18th century and many people did not know what to do.

Question 11

Extent : Type of soil

Answer 11

Type of soil : places with loose, unconsolidated soil will experience more damage
Buildings built on soft (loose and unconsolidated) soil tend to suffer more damages than buildings built on solid rock during an earthquake because soft soil is naturally less stable than solid rock.
As a result, the ground will shake more from the earthquake vibrations, amplifying the energy.
During an earthquake, loose and unconsolidated soil may undergo soil liquefaction, causing structures to topple, fall and sink, causing more damage.

Question 12

Extent : Type of Soil - example

Answer 12

Example:
Although the epicenter was not very close, the 2010 Christchurch earthquake caused massive damages to the city of Christchurch because of soil liquefaction.

Question 13

Risks : Tsunami

Answer 13

Tsunami : tsunamis are dangerous because they sweep, engulf, wash, swallow EVERYTHING in its path
An underwater earthquake occurs
Seismic energy from the earthquake displaces and forces out a mass of seawater
Out at sea, tsunami waves are small. They may pass undetected.
On reaching shallow water, greater friction slows down the waves and forces them to increase in height
Large tsunami waves of up to 15m in height crash onto shore destroying and flooding everything in its path.

Question 14

RIsks : Tsunami - example

Answer 14

Example:
The 2004 Indian Ocean earthquake resulted in a large tsunami that hit many countries that killed over 200 000 people and caused countless buildings to be damaged and destroyed.

Question 15

Risks : Landslides

Answer 15

Landslides : landslides are dangerous because the land collapses, bringing down everything on it
The shaking of the ground can weaken the slopes of hills and mountains.
The unstable slopes can result in rapid downslope movement of soil, rock and vegetation debris, forming a landslide

Question 16

Risks : Landslides - example

Answer 16

Example:
For example, an earthquake off the coast of Peru in 1970 destabilized the slopes of Mount Huascaran and triggered a massive landslide that killed 18 000 people in the town of Ranrahirca

Question 17

Risks : DIsruption of Services

Answer 17

The shaking of the ground can cause power lines and telecommunication lines to break
This can cause further problems because people are not able to communicate and get help
Breakage of power lines can cause short circuits and fires
The shaking of the ground can also cause water and sewage pipes to break
This can cause other problems like fires and contamination of drinking water.

Question 18

Risks : Disruption of services - example

Answer 18

Example:
Fire broke out during the 1995 Kobe Earthquake due to the damaged power lines. To make things worse there was no water pressure to put out the fire due to water pipes bursting too.

Question 19

Risks : Destruction of Infrastructure

Answer 19

Destruction of infrastructure : intense shaking causes infrastructure to be damaged and destroyed
The shaking of the ground can crucial infrastructure like roads and bridges to collapse
This can cause problems because people are not able to escape and help is unable to reach the needy
It is also difficult for people to return to normal life or daily commute after the earthquake

Question 20

Risks : Destruction of infrastructure - example

Answer 20

Example:

During the 1995 Kobe Earthquake, many roads and bridges collapsed, and railways were also damaged.

Question 21

Risks : Destruction of Properties

Answer 21

Destruction of properties : intense shaking causes homes to be damaged and destroyed
When buildings collapse, people are trapped under the rubble or killed when they are hit by falling debris

Question 22

Preparation : Land use regulation

Answer 22

Refers to restrictions of development in certain areas to minimize damage, in the event of an earthquake or a tsunami

Question 23

Preparation : Land Use Regulation - success

Answer 23

Successes:
In California, USA, all new building developments are not built across fault lines and areas at risk of liquefaction.
New buildings are prohibited from being built on low-lying land that is vulnerable to tsunamis.
This is common along the coasts of Japan and North America, where the Pacific Ring of Fire is located.

Question 24

Preparation : Land Use Regulation - Limitation

Answer 24

Limitations:
It is difficult to implement this in areas that have already been built-up or privately owned.
Private owners may also be reluctant to move even if the government offers compensation, which is already a very costly move

Question 25

Preparation : Enhancing Infrastructure

Answer 25

Refers to the use of advanced engineering to reduce the risk of building collapsing, and reducing damage caused during earthquakes.

Question 26

Preparation : Enhancing Infrastructure - Success

Answer 26

Successes:
Taipei 101 in Taiwan, is made up of steel and reinforced concrete, which is better able to withstand earthquakes.
It also has a foundation reinforced by heavy metal bars, and has a damping device that acts as a counterweight and prevents the building from shaking, minimizing damage done.

Question 27

Preparation : Enhancing Infrastructure - Limitation

Answer 27

Limitations:
Earthquake resistant buildings are expensive and add to the cost of construction and maintenance of buildings. LDCs may not be able to afford such buildings.
LDC’s may not be able to afford such buildings - e.g. thousands of sch children were killed in 2008 Sichuan Earthquakes, as 70 000 poorly built schools collapsed.

Question 28

Preparation : Emergency Drills

Answer 28

Emergency drills help to create awareness amongst the population, and reduce panic during the event, as people would know what they are supposed to do and how to get to safety.

Question 29

Preparation : Emergency Drills - example

Answer 29

Since 1960, Japan has conducted emergency drills on 1st September of every year to commemorate Disaster Preparation Day.
Main roads are blocked to simulate possible road conditions in the event of an earthquake and emergency vehicles would have to seek alternative pathways to reach affected areas.
In LDCs, countries are unable to afford expensive technology to minimize effects of earthquakes, thus they rely on drills to save lives. 40 000 people in New Delhi, India, participated in a simulated magnitude 7.2 Earthquake in 2012.

Question 30

Preparation : Earthquake monitoring systems

Answer 30

Provides an estimation of frequency and magnitude of earthquakes at particular fault lines.

Question 31

Preparation : Earthquake monitoring and warning system - example

Answer 31

USA uses seismic risk maps
Earthquake sensors can also help monitor the frequency of vibration and detect possible developments of an earthquake - e.g. earthquake motion data is gathered from hundreds of observation stations installed on the roads and bridges in Japan.

Question 32

Preparation : Earthquake monitoring and warning system - limitation

Answer 32

Earthquake sensors are expensive to obtain, install and use.

They also usually only provides us with a few seconds of head start before the earthquake occurs (not enough time)

Question 33

Preparation : Tsunami monitoring and warning system

Answer 33

Provides people with more time to get to safety, saving more lives

Question 34

Preparation : Tsunami monitoring and warning system - sucess

Answer 34

Successes:
Helps monitor and predict tsunamis and warns people about it
E.g. a network of pressure sensors, seismographs and deep ocean tsunami detectors are located in Hawaii, USA.

Question 35

Preparation : Tsunami monitoring and warning system - limitation

Answer 35

Limitations:
Prone to giving false alarms and causes unnecessary panic
There is little time for evacuation after an approaching tsunami has been detected.

Question 36

Short Term Responses : Search and Rescue teams

Answer 36

100 000 members of the self-defense forces, the police, the coast guard and local disaster response teams were sent to the disaster area.
Sniffer dogs and heat sensors were deployed and successfully rescues many
Survivors could register their names, which helped identify missing people and reunite family and friends

Question 37

Short Term Responses : Emergency food and medical supplies

Answer 37

Rescue centers provided places for survivors to eat, bathe and sleep
People exposed to high levels of radiation were screened and isolated

Question 38

Long Term Responses : Rebuilding of infrastructure

Answer 38

The Bank of Japan prepared to pump an additional US $183 billion into the economy to ensure that there was adequate funding for rebuilding the affected area and to prevent bankruptcies from loss of jobs and destruction of infrastructure.

Question 39

Long Term Responses : Provision of healthcare

Answer 39

Trained personnel provided counselling for post-disaster anxiety and depression, as the disaster left many traumatized