Earthquakes and Volcanoes Flashcards
What is a destructive plate boundary?
- Happens when two plates, usually volcanic and continental plates, move towards each other.
- A subduction zone is reated as the oceanic plate is thrusted underneath the continental plate
- Plates melt due to friction created and newly formed magma rises to the surface creating a volcano
- E.g. - Pacific and Australian plates
What is a construcive plate boundary?
- Occurs when tw plates move apart from each other and the space is filled with crus material from olten magma.
- Undersea volcanoes can form at these divergent boundaries.
- E.g. Mis Atlantic Ridge, Red Sea Rift and Gabbel Ridge
What is a collision plate boundary?
- Occurs when two continental plates meet head on
- No subduction zone as both plates are equal in density and strength
- Sedment between the plates is forced up and results in the formation of Fold Mountains
- E.g. - Indiand Eurasian plates causing the Himalays
What is a conservative plate boundary?
- Occurs when two plates slide past each other
- These plates have been sliding past each other for millions of years
- The build up of friction and pressure is realised in the form of an earthquake
- E.g. - Pacific and North American plate int he San Andreas fault
What is the focus?
- The center of the earthquake beneath the ground
What is the epicentre?
- The point on the surface directly above the foucus
What is the cause of an earthquake?
- Constant movement of the earth’s surfaces
- Some places ther eis strain between differnt point where the rcok cannot withstand any mroe bending
- Rock therefore breaks the two sides move
- Elastic rebound describes the movement of the build up of forces causing a snap eventually
How is magma formed?
- When the pressure decreases within parts of the upper mantle within a subduction zone
- Lower pressure above the submerged plate and below the top plate allows the rock to melt
What is magma made out of?
- Mixture of rocks, solids and gases
When does magma rise?
- When the pressure within the magma chamber is greater than the strength of the crust as it begins to break though
What is the Richter Scale?
- Measures the earthquake’s strength according to the amount of energy released.
What is the Mercalli Scale?
- A scale based on what people experience and the amunt of damage done during an earthquake
What factors will vary the amount of damage caused by an earthquake?
- Depth of focus
- Type of rock
What can shock waves do during an earthquake?
- Liquefy soft rocks so they become like liquid
- Causes the foundation of buldings to collapse
What do volcanoes consist of?
- Magma chamber, pipes and vent that expel magam, gas and steam
What effect do lava flows have?
- Destroy farmland, buildings and line of transport
What does ash do?
- Gets carried in the wind and can affect large areas
- Blankets everything
- roofs of buildings can collapse if the there is a large amount of ash deposited
What gass are emitted by volcanoes?
- CO2, sulphur, cynaide
What is the social short term impact of earthquakes?
- Transport and communication links may be disrupted
- Water pipes may burst and water supplies may become contaminated
- Shops and businesses may be destroyed
- Prisons may become damaged leading ot he escape of crimals and therefore increases rate of crime in the future
What are the environmental short term impacts of earthquakes?
- Landscape may be destroyed
- Fires can spread due to gas pipe explosions
- Landslides may occur
- Tsunamis may cause coastal flooding
- Rubble rom fallen buildings may block roads and pathways
- Hindering rescue and reliefworkers to acess the area
- Lack of suitable areas to set up aid camps
What are the social long term impacts of earthquakes?
- Disease may spread
- People have to be re-housed
- Some people have to migrate
- Decline of industries
- Government projects postponed
- Cost of rebuilding in settlement is high
What are the enviornmental long term impacts of earthquakes?
- Poeple could be pushed into unsuitable areas to live in, e.g. floodplains
- Important natural and human landmarks may be lost
What are the social short term impacts of volcanoes?
- Power supllies could be cut
- Roads and bridges could be unusable
- Water supply could become contaminated
What are the environmental short term impacts of volcanoes?
- Smell of sulphuric gas in the air
- Raised sea temperatures caused by pyroclastic flow entering the water
- Food chains will be altered and unbalanced
- Ash can cover areas and collapse houses
- Landslides
What are the social long term impacts of volcanoes?
- Long term exposure to volcanic fumes casue respiratory problems
- Migration due to their homes being destroyed
What are the enviormental long term impacts of volcanoes?
- Lahars will occur everytime it rains
- Ash and lava make the soil infertile for along time
- Silting in rivers and lakes
- Volcanic pollution can affect the atmosphere
- Reduces solar energy reaching the earth by 5-10%
What is the background to Haiti earthquake?
- Occured 13th January 2010
- Magitude 7.0 on Richter Scale
- Focus was 10km below the surface
- At least 52 aftershocks by 24th January
- HDI level of 0.404 (145th)
What problems caused Haiti to have poor preparation to the earthquake?
- Poltical, economic, social conditions made it dificult to establish an early warning system
- No earthquakes drills were in place
- No educational programmes
- Haiti had a small budget
What mitigation was there during the Haiti earthquake?
- No help from government
- Haiti’s airports were blocked with debris and ports blocked too
- Inadequate emergency services and supplies
- Many people lived in slums
What short term mitigation was there after the Haiti earthquake?
- Total aid gived was $10 billion
- Health camps set up
- 4% of $5.4 billion aid was spent by 2011
- No emergency plan in immediate aftermath
- No help from government
- Lack of co-ordination by NGOs
What long term mitigation was in place after the Haiti earthquake?
- Haiti’s Action Plan for National Recovery and Developement established.
- Too dependant on NGOS
- Plan was to create jobs with the government working alongside small businesses in the next 10 years
- Boost economy through agriculture
What was the background to Hurricane Sandy?
- New York on 29th october 2012
- Category 2
- GNI per capita - $48,586
What mitigation was put in place before Hurricane Sandy?
- Mayor adressed city
- Evacuation zones set up
- Evacuation aided by the police
- Text sent to inhabtants warning to evacuate
- FEMA displayed etailed information about hurricane and what to do whent he hurricane strikes
- Warning centres and water distrubutors set up
- UGS set up more than 150 storm surges snsors at key locations to give detailed developement of the coast
What mitigation was put in place during the Hurricane Sandy?
- AT&T provided phone pods and chargers in evacuation camos
- FEMA, US Aid and Red Cross aided in evacuation efforts
- 400 National Guard member delivered food and water in Coney Island
- Sand bangs placed around buidings in New York Stock Exchange.
What short term mitigation was put into place after Hurricane Sandy?
- FEMA opened 19 Disaster Recovery Centres and 27 shetlers
- FEMA and American Red Cross delivered thosuands of meals and blankets
What long term mitigation was put into place after Hurricane Sandy?
- Appraisal regarding rebuilding of communites as they would just get flooded in future hazards
- Flood barriers to be erected in coastal areas
- Artificial wetlands planned in suitable areas to obsturct storm surges
