Chapter 3

• Nature of earthquakes: Duration of shaking:

  • Length of time influences extent of damage
  • Structures more likely to collapse after long periods of stress
  • People more likely to be trapped in collapsed infrastructure

  Example: 2011 Tohoko Japan earthquake:

  • lasted 6 mins and caused massive damage to buildings
• Nature of earthquakes: time of shaking:

  • Time influences what people might be doing during time of disaster
  • If it occurs at night, people are less alert and cannot respond quickly
  • If it occurs during day time, people are more alert and are able to respond quickly

  Example: Kobe Japan earthquake 1955:

  • Happened in early morning
  • Less people awake, more got trapped in homes leading to >6000 deaths
• Vulnerability (earthquake):

  • The poorer the quality of buildings, the more vulnerable it is to collapsing, causing more people to be trapped and killed
  • Buildings are vulnerable when they are made of poor quality materials, do not follow building codes or lack earthquake resistant features

  Example: 2010 Haiti earthquake

  • buildings were made of poor quality materials and was poorly reinforced
  • 90% of the buildings near epicenter was destroyed causing > 220 000 lives to be lost
• Vulnerability (earthquakes): soil and rock properties:

  • Loose soil makes it more likely for soil liquefaction to occur
  • Buildings more likely to collapse when on top of liquefied soil causing more people to be trapped
  • Loose soil allows seismic waves to be amplified causing there to be more shaking

  Example: 2010 Haiti earthquake

  • Port-au-Prince was on relatively soft soil
  • This caused the seismic waves to be amplified causing the collapse of many buildings and the death of 220 000 people
• Exposure ( earthquakes): population density:

  • Higher the population density, greater the number of buildings and people exposed to disaster
  • More people trapped when buildings collapse

  Example: 1955 Kobe Japan earthquake

  • killed 6000 people
  • Population density is around 3000/km^3
• Exposure(earthquake): distance from epicenter:

  • Nearer to epicenter, less energy is absorbed before seismic waves reach city
  • Seismic waves stronger and causes more buildings to collapse, trapping more people

  Example: 2010 Haiti earthquake:

  • Port-au-Prince was only 25km away from the epicenter
  • Resulted in 220 000 people dead
• Nature of disaster (volcanoes): Low silica magma:

  • Dissolved gases can escape easily resulting in a more gentle and effusive eruption
  • Lava flows a longer distance before cooling and solidifying, increasing the extent of damage as it travels further from vent
  • Rarely kill as people can easily avoid lava

  Example: 2018 Kilauea eruption in Hawaii:

  • 24 injured
  • 600 homes destroyed
  • 800 USD in property damage
• Nature of disaster (volcanoes): High silica magma:

  • Dissolved gases cannot escape easily resulting in a explosive eruption
  • May form destructive pyroclastic flow causing wide spread damage
  • Explosive volcanic matter (volcanic bombs, ashes) might strike people and injure/kill them

  Example: Mount Merapi eruption in 2010, Indonesia:

  • Pyroclastic flow travelled 3km
  • Volcanic bombs spread over 10km
  • 350 000 people evacuated and 350 killed
• Vulnerability (volcano): availability of ground water:

  • More groundwater available, more likely lahars will form
  • Lahars can bury and destroy property, increasing likelihood of injuries and loss of life
  • Water comes in the form of melted ice and snow, groundwater released through cracks and fractures during volcanic eruptions and existing water bodies

  Example: Mount Pinatubo eruption 1991, Philippines:

  • Lahars triggered by heavy rainfall
  • Destroyed 100 000 homes
• Vulnerability (volcanoes): Wind conditions:

  • Distribution of ash and tephra can be carried to human settlements via the wind
  • Heavy particles remain near volcano while finer ash particles can travel further
  • Ash causes people to develop respiratory problems and can damage buildings when weight of ash causes roof to collapse
  • Farmland and crops are destroyed when they get buried with ash

  Example: Mount Pinatubo eruption 1991:

  • wind speed >20km
  • >90 000 hectares of farmland destroyed
• Exposure (volcano): Presence of human settlements

  • More human settlements = more people and buildings exposed to hazards
  • However some may choose to live near volcano due to the rich soil, geothermal energy or valuable materials it provides

  Example: Mount Sinaburg:

  • Has fertile soil for farming
  • People still live and work 3km away from volcano despite eruptions in 2010
• Land use planning to reduce exposure to hazards:

  • Controls and minimizes damage in high risk areas
  • Uses hazard maps to determine levels of risk and likely extent of hazard to implement strict building codes
  • Decreases potential loss of lives and damage to properties

  Example: Touni-hongo village, Japan:

  • Residential areas shifted to higher grounds after 1933 tsunami
  • When tsunami caused by 2011 Tohoku earthquake struct, houses on higher ground was not destroyed
• Hazard-resistance building designs to reduce vulnerability:

  • Using shock absorbers can help absorb vibrations
  • Reinforcing buildings with diagonal cross braces helps to retain building shape during earthquakes
  • This make it less likely for people to be trapped under collapsed buildings

  Example: Taipei 101 building, Taiwan

  • Has weighted damper near the top of the building to prevent it from swaying during earthquakes, making it less likely to collapse
• Reducing vulnerability: Disaster monitoring and warning system

  • They help to detect seismic waves and ground deformation to warn and make predictions on potential hazards
  • Earthquake early warning systems detect seismic waves and sent alerts to smart devices, allowing for people to evacuate
  • Can also identify rise areas

  Example: 2011 Tohoku Japan earthquake:

  • Warning systems detected tremors and signals were sent to stop bullet trains, saving countless of lives
• Increasing preparedness: Education

  • Allows people to understand how to deal with hazards such as to seek shelter from volcanic ash and to seal windows and doors
  • First aid training allows for people to administer basic medical care to injured to allow them to remain mobile and be able to evacuate
  • Also includes development plans that help the community recover such as having makeshift shelters for survivors
• Increasing preparedness: Drills

  • allows people to be aware of evacuation procedures and routes, reducing chance of them being trapped
  • Drills for volcanic eruptions teaches people to avoid downwind of volcano to avoid volcanic ash while tsunami drills teaches people to head to tsunami inundation zones

  Example: Tohoku Japan earthquake 2011

  • Schools in Kamashi city had evacuation drills that helped students evacuate quickly to higher ground to avoid the tsunami
• Challenges in building community resilience: Lack of resources

  • Lack of resources makes it difficult to reduce vulnerability as reinforcing buildings and land use planning requires money
  • Developing countries often lack resources and their governments may use the resources they have to develop the economy instead of disaster prevention

  Example: Bangladesh

  • 30% of the population live below poverty line
  • Resources are put into economic development
  • 21% of the buildings in the capital are unreinforced and 77% of buildings that are reinforced is not designed to resist earthquakes
• Challenges in building community resilience: Inability of community to organize themselves

  • Limits community's ability to respond
  • Limited by the lack of effort to educate and train community, political instability or corruption

  Example: Haiti earthquake 2010

  • Community unable to organize themselves as they did not know what to do
  • Lacked healthcare workers that limited availability of medicine
  • Poor law enforcement led to looting cases, chaos and unrest
• Strategies to respond to disasters: Search and rescue efforts:

  • Immediate life saving response that involves finding and saving trapped survivors
  • Having skilled rescuers and advance equipment makes process much faster
  • Without such efforts, survivors may die from being trapped due to injuries, lack of food and water and crush syndrome

  Example: 2020 Aegean Sea Turkey earthquake

  • >8000 search and rescue teams deployed, rescuing 106 people
• Strategies to respond: Timely evacuations (for earthquakes)

  • Buildings may collapse during earthquakes and need to be evacuated to open space
  • After shocks may also cause weakened buildings to collapse
  • Basic services may be disrupted thus needing temporary shelters to be built
  • Tsunamis cause by earthquakes requires people to be evacuated to high grounds

  Example: 2011 Tohoku Japan earthquake

  • Students in Kamashi city evacuated to high grounds, saving 3000 student's lives
• Responding to hazards: Timely evacuation (for volcanoes)

  • People evacuated from danger zones around volcano to avoid hazards such as volcanic ash, tephra, lahars, volcanic bombs and pyroclastic flows

  Example: Before Mount Merapi eruption in 2010

  • Indonesian authorities held massive evacuation efforts that moved people to 700 evacuation centers, saving >10 000 lives
• Responding to disasters: Provision of basic needs (food and water):

  • Lack of water due to damaged pipes and contaminated water source
  • Need clean water to prevent dehydration and spread of water borne diseases
  • Lack of food due to closure of shops and available food being unsafe for consumption
  • Need food to prevent starvation

  Examples:

  2010 Haiti Earthquake:

  • International committee of red cross provided water for 12 000 people

  2017 Mount Agung eruption, Indonesia:

  • Government and NGOs provided food for 75 000 evacuees
• Responding to disasters: providing medical care

  • Lack of healthcare due to destroyed hospitals
  • Many require medical attention after a disaster and its important as it helps prevent spread of diseases and save lives
  • Many also require counseling to deal with loses and trauma

  Examples:

  2018 Fuego eruption in Guatemala:

  • World vision donated medical supplies and hygiene kits to survivors

  2018 Palu Indonesia earthquake:

  • Volunteer groups help to provide counselling to children to help them deal with losing family and homes
• Recovering from disasters:

  • Construct hazard resistant buildings and infrastructure
  • Retrofit existing structures with hazard resistant features
  • Provide housing assistance by providing housing that can better withstand hazards

  Example 2011 Tohoku Japan earthquakes

  • Majority of the 500 000 people displaced by earthquake received housing with enhanced Tsunami resistant features
  • Ground level for housing raised and sea walls were built
• Challenges in disaster management: lack of resources

  • Lack of financial or technological resources hamper response efforts

  Example: 2010 Haiti earthquake

  • Lacked ambulances to transport injured and heavy machinery to remove rubble, leading rescue team to manually remove rubble
• Challenges in disaster management: lack of cooperation

  • Disagreements between stakeholders on disaster management strategies due to lack of knowledge
  • High cost of implementing disaster risk management strategies
  • Communities reluctant to purchase insurance and insurance companies reluctant to provide insurance due to high cost

  Example:

  Nepal earthquake 2015:

  • Government and opposition parties created National Reconstruction authority but due to political disagreements, repair works only started 9 months later
  • Only 10-20% of property are insured against earthquakes due to high insurance cost
• Disaster risk management: Prevent disaster risk before occurrence of tectonic hazard

  • Design hazard resistant buildings that can withstand hazard and do not collapse easily

  Example: Taipei 101

  • Has weighted damper that balances out ground shaking, reducing the sway of building during earthquakes
• Disaster risk management: Reduce risk as disaster occurs

  • Early monitoring and warning systems for tsunamis and earthquakes that enables timely evacuation
• Disaster risk management: Manage risk after occurrence

  • Having insurance coverage that offer financial payouts for people to rebuild after disaster
  • Brings about quicker recovery from impact of hazard
• Environmental consequences of hazards:

  • Loss of biodiversity when ecosystems are destroyed when forest and wetlands are buried by landslides
  • Debris from landslide pollute rivers, killing aquatic life
  • Debris also block rivers, causing floods that can damage nearby ecosystem
• Social consequences of hazards:

  • Hazards like tsunamis causes loss of live when people drown in waves
  • Houses are destroyed causing people to become homeless, lowering standard of living
  • Seawater from tsunami can contaminate sources of drinking water, causing water pollution and spread of waterborne diseases
  • People might suffer from psychological trauma from loss of home and family, affecting their metal well-being
• Economic consequences of hazards:

  • Destruction of homes and property causes people financial damage due to money needed for repairs
  • Businesses lose income due to damage to property
  • Government need to spend money to repair and rebuild after disaster
• Case study: Impact of 2004 Indian Ocean Tsunami

  • Many people in Aceh lost their homes, jobs and source of income, affecting Aceh’s development
  • Population of people living below the poverty line increased from 30% to 50%
• Importance of reducing disaster risk:

  • Consequences can be very severe and hinders development
  • Reducing risk is cost effective investment and the cost is often smaller than cost incurred in the disaster