Reducing the Impact of Earthquakes & Volcanoes (Cambridge (CIE) O Level Geography)

Reducing the Impacts of Earthquakes & Volcanoes

• The responses to earthquakes and volcanic eruptions can be short term or long term

  • Short term responses are those which happen straight after an event and include aid and disaster relief

  • Long term responses aim to reduce the impact of future hazard events and include risk assessments and hazard mapping

Earthquakes - long term responses

• Accurate prediction of earthquakes is not currently possible, but monitoring is

• Many different methods of monitoring are being used to help research possible prediction methods:

  • Tiltmeters - which monitors ground changes

  • Clusters of small earthquakes

  • Changes in radon gas emissions

  • Changes in animal behaviour

  • Remote sensing of ground movement using satellites

• In developed countries building design and engineering is commonly used to reduce the impact of earthquakes

• Building regulations and codes require new buildings to include earthquake resistant features:

  • Shutters on windows prevent falling glass

  • Cross-bracing or diagonal bracing of steel frames

  • Flexible building materials

  • Foundations sunk deep into the bedrock

  • Frames which sway with the earthquake tremors

  • Rubber shock absorbers to reduce tremors moving through the building

  • Reinforce walls/pillars with concrete

  • Shatter proof/reinforced glass

  • Fire resistant materials

  • Automatic cut off for gas/electricity

• In many countries earthquake drills are regularly carried out

• The drills help people to prepare for what to do in an earthquake to protect themselves

• Education about how to prepare homes means that people are less likely to be injured by falling objects and furniture

Volcanoes and earthquakes - long term responses

• There are some examples of planning which are used in both areas vulnerable to earthquakes and those vulnerable to volcanic eruptions

• In vulnerable areas:

  • Remote sensing of the Earth's surface by satellites such as Sentinel 1 provides data about changes in ground movement

  • Geographic Information Systems (GIS) provides layers of data such as:

    • vulnerable areas

    • land use

    • infrastructure such as roads

  • GIS data is then used to assist with land use planning

  • Land Use Planning

    • Mapping of areas most at risk from earthquakes

    • Planning can ensure that valuable services such as the fire service and hospitals are not built in high risk areas

    • Densely populated housing can be located away from high-risk areas

Case Study: Nepal

• Nepal is one of the poorest countries in the world with a Gross Domestic Product (GDP) per capita of under $1000 

• Located between China and India, Nepal is a landlocked country

• In 2015 80% of the population lived in rural, often remote, communities

• In April 2015 at 11.26 am Nepal was struck by an earthquake, magnitude 7.8

• The epicentre was 80 km northwest of Kathmandu in the Gorka district

• The focus was shallow at only 15 km beneath the surface

• Over 300 aftershocks followed the main earthquake

Location of Nepal Earthquake

Cause 

• Nepal is located on a collision boundary between the Indian and Eurasian plates

Effects

• Approximately 9000 deaths 

• Over 20,000 people injured

• Electricity and water supplies cut

• 7000 schools and 1000 health facilities were damaged or destroyed

• Almost 3.5 million people were made homeless

• Offices, shops and factories were destroyed meaning people were unable to make a living

• UNESCO world heritage sites destroyed as well as many temples

• Loss of tourist income which Nepal is reliant on

• Avalanches on Mount Everest and in the Langtang Valley

• Landslides which blocked roads and rivers

• Damages estimated at between $7 and $10 billion about 35% of the GDP

Immediate responses

• Donations of money and aid from around the world totally $3 billion including $3.3 million from China and $51 million from the UK 

• Many countries sent aid in the form of:

  • Temporary shelters

  • Medicines

  • Food

  • Water

  • Clothing

  • Search and rescue teams

  • Medical staff

• 90% of the Nepalese army were mobilised 

• Tent cities were set up in Kathmandu for those made homeless

• GIS crisis mapping tool was used to co-ordinate the response

• $3 million grant was provided by the Asian Development Bank for emergency relief

Long term response

• Landslides were cleared and roads repaired to restore access to remote rural communities

• Schools were rebuilt

• Earthquake drills were introduced to provide people with education about what to do in the event of an earthquake

• Stricter building codes with more enforcement

• $200 million was provided by the Asian Development Bank for rebuilding

• A new government task force was set up to plan for future earthquake events 

Case Study: La Palma

• Part of the Canary Islands, La Palma is located in the Atlantic Ocean off the coast of North Africa

• The Canary Islands are an [popover id="RAr2r~3MbVY7biGB" label=''autonomous region"] of Spain

• There are 33 volcanoes across the Canary Islands, 10 of which are in La Palma

• La Palma has a population of 85,000

• The Cumbre Viejo volcano on La Palma began to erupt on the 19th September 2021 and the eruption lasted for almost three months

• The eruption was VEI 2 to VEI 3

Location of Cumbre Vieja Volcano

Cause

• La Palma and the other Canary Islands are located on the African plate

• The islands are an archipelago which has formed as the result of a hot spot

• This means that they are not located on a plate boundary but over a magma plume

Signs of eruption

• Deformation of the mountain indicated rising magma about a week before the eruption

• Between 10-19th September there were over 25,000 earthquakes - an 'earthquake swarm' 

Effects

• Over 7,000 people had to be evacuated from their homes

• Almost 1,500 houses were destroyed by the lava flow

• Over 1,500 other buildings such as churches, shops, schools were destroyed

• The lava flow cut across the coastal highway

• Water supply was cut off for almost 3,000 people

• 400 hectares of banana farms were destroyed

• Almost 1,300 hectares of land was effected

• 1 death

• About 20,000 people were exposed to the eruption and its effects

• Air traffic disruption

• €1 billion damages

Immediate response

• A warning was issued of an eruption on 13th September and 40 people and livestock were evacuated

• A further 1000 people were evacuated after the eruption began on the 19th September

• 5600 more people were evacuated over the next few weeks

• Alert level was raised to red

• Air traffic was briefly suspended

• Constant monitoring of lava flow and gas emissions to ensure the safety of the population

• Food and shelter were provided for those made homeless

• €5.4 million advanced payment donated by the EU

Long term response

• Spain promised €400 million to La Palma for rebuilding

• Prefabricated housing was built for those made homeless but six months on many people were still living in hotels and with family/friends

• Constant monitoring of the volcano and others on La Palma

• Improved crisis management processes now in place for future eruptions