What are the hazards associated with earthquake and volcanic activity? Flashcards
What is a collision boundary?
plate boundary in which two similar plates come together – neither is destroyed but both are folded to form fold mountains, e.g. the Eurasion and Indian plates which collide and form the Himalayas
What is a conservative boundary?
plate boundary in which two similar plates move past each other – neither is destroyed but earthquake activity is common, e.g. San Andreas fault where the North American plate and Pacific plate move in the same direction but at different speeds. Also called transform boundary
What is a constructive boundary?
plate boundary at which new material is being created e.g. Iceland. Also called divergent boundary or spreading ridge
What is a destructive boundary?
plate boundary in which material is destroyed at a subduction zone e.g. off the west coast of South America
The tectonic plates that make up the Earth’s crust move about on….
…. convection currents in the mantle
An earthquake is…
… the shaking and vibration of the Earth’s crust due to movement of the Earth’s plates (plate tectonics). Earthquakes can happen along any type of plate boundary.
Earthquakes occur when…
… tension is released from inside the crust. Plates do not always move smoothly alongside each other and sometimes get stuck. When this happens pressure builds up. When this pressure is eventually released, an earthquake tends to occur.
What is the point inside the crust where the pressure is released called?
The focus
How are earthquakes energy released?
in seismic waves
Where are the waves of earthquakes felt most strongly?
at the epicentre
Primary hazards of earthquakes
- Ground shaking
- Landslides
- Faulting at surface
Secondary hazards of earthquakes
- Liquefaction
- Ground failure
- Rock falls
- Mud flows
- Tsunamis
Primary impacts of earthquakes
- Destruction
- Casualties
- Landslides
- Fires
- Loss of services/utilities and communications
- Shock and traumatic stress
- Violence (looting)
Secondary impacts of earthquakes
- Disease (sewage and water pipes broken)
- Loss of infrastructure
- Housing
- Jobs
- Food and water shortages
- Tsunamis
- Floods
Tertiary impacts of earthquakes
- Cost of recovery
- Loss of crops
- Damage to mines/industries
- Trade
- Long-term depression
- Out-migration
Three responses to earthquakes:
- Emergency aid
- Short term aid
- Long term aid
What does emergency aid consist of?
- Rescue
- Tents
- Medicines
- Food
- Water
- Often involving the military and charities
What does short term aid consist of?
- Rehousing people
- Rebuilding hospitals
- Repairing infrastructure
What does long term aid consist of?
- Moving population
- Improving warning systems
- Emergency planning
When was the Kashmir earthquake?
October 2005
What magnitude was the Kashmir earthquake?
7.7 - one of the worst of the twentieth and twenty-first centuries.
How many aftershocks in 24 hours were there after the Kashmir earthquake?
22
What is an aftershock?
Aftershocks are earthquakes that follow the largest shock of an earthquake sequence. They are smaller than the mainshock and within 1-2 rupture lengths distance from the mainshock. Aftershocks can continue over a period of weeks, months, or years.
What was the cause of the Kashmir earthquake?
- The cause of the earthquake was the Indo-Australian plate moving against the Eurasian plate
What was the death toll from the Kashmir earthquake, October 2005?
more than 73,000
What was the blame for the devastating human impact of the Kashmir earthquake, October 2005?
The countries lack of resources
What was international relief like for the Kashmir earthquake, October 2005?
o International relief was chaotic and underfunded; and hundreds of thousands were at risk as the bitter Himalayan winter approached
What was there a lack of in the Kashmir earthquake?
o There were a shortage of tents suitable to withstand the Kashmiri winter, as well as blankets, sleeping bags, warm clothes, medicine and food
The Kashmir earthquake did not affect people like the Asian tsunami, December 2004, did -
Whatever the reason, the earthquake did not provoke the response from the rest of the world that it desperately needed
When and where was the Earthquake in Los Angeles?
Northridge, 1994
What magnitude was the Northridge earthquake?
6.7
What time was the Kashmir earthquake?
9.20am - schools full
What magnitude was the Northridge earthquake?
6.7
What were the physical causes of devastation in the Kashmir earthquake?
- Australian plate colliding with Eurasian plate
- Mountainous area
- Remote
- Extreme climate – winter snows
What were the human causes of the Kashmir earthquake?
- Poverty
- Poor-quality buildings
- Disputed area between India and Pakistan
What were the environmental impacts of the Kashmir earthquake?
- Landslides
- Diseases – tetanus, cholera
- Contaminated water
- Cold killed many
What were the social impacts of the Kashmir earthquake?
- 73,000 killed and 69,000 injured
- 3 million left homeless
- Shock and stress
- Young generation wiped out
What were the economic impacts of the Kashmir earthquake?
- US$5 billion of damage
- 1442 schools collapsed
- Bridges and roads destroyed so some areas left isolated for weeks
- Wells destroyed
- Food stores destroyed
- Phone and power lines broken
Why were the responses to the Kashmir earthquake slow?
remote
What were the short term responses to the Kashmir earthquake?
- Search and rescue – slow reaction by army
- Lack of tents, food etc.
What were the long term responses to the Kashmir earthquake?
- Large international efforts (but less than for tsunamis, as little-known area)
- Political unrest at failure of government to act and its corruption
- Rebuilding has been slow
- Still military tension in area
What were the physical causes of the Northridge Los Angeles earthquake in 1994?
- A previously unknown buried thrust fault
- Steep hillsides
What were the human causes of the Northridge Los Angeles earthquake in 1994?
- Building on the fault line
- Many older buildings
- Bridges failed so difficult to get aid in
What were the environmental impacts of the Northridge earthquake?
- Landslides
- Fires
- Disease – respiratory from spores
What were the social impacts of the Northridge earthquake, 1994?
- 66 killed and 9000 injured
- Homes damaged
- Looting in poor areas
- Shock and stress
When abouts was the 1994 earthquake in Northridge Los Angeles?
January
What were the responses like to the Northridge earthquake?
Fast, as prepared
What were the responses like to the Northridge earthquake?
d
What were the long term responses to the Northridge earthquake?
- Reconstruction
- Laws – by January 2005 all hospitals had to have earthquake proof A and E rooms
- California state set up its own low-cost earthquake insurance
- Bridges reinforced
- Vulnerable buildings inspected and reinforced
What were the long term responses to the Northridge earthquake?
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What are the primary hazards of volcanoes?
o Landslides o Fire o Mud flows o Rock bombs o Lava flows o Gas o Heat o Pyroclastic flows
What are the secondary hazards of volcanoes?
o Tsunamis
o Crop failure
o Disease
o Famine
What are the primary impacts of volcanoes?
o Destruction
o Casualties
o Landslides
o Fires
What are the secondary impacts of volcanoes?
o Disease
o Loss of infrastructure
o Housing and jobs
o Food and water shortages
What are the tertiary impacts of volcanoes?
o Cost of recovery
o Loss of crops
o Damage to mines/industries
o Trade
What are the emergency aid responses to volcanoes?
o Rescue o Tents o Medicines o Food o Water o Often involving charities and the military
What are the short term aid responses to volcanoes?
o Rehousing people
o Rebuilding hospitals
o Repairing infrastructure
What are the long term aid responses to volcanoes?
o Moving population
o Improving warning systems
o Emergency planning
What are pyroclastic flows?
Super-heated flows of ash, cinders and pumice capable of travelling at speeds of up to 160km and reaching temperatures in excess of 1000 degrees Celsius
Where is Monsterrat?
small volcanic island in the Caribbean
What does the island of Monsterrat belong to?
- It belongs to the Lesser Antilles island arc: a curved chai of volcanic islands formed by subduction along the margin of two oceanic plates
- In this instance the subduction of the North American plate explains the 19 active volcanoes in the island chain which have erupted 33 times in the past 200 years
What does the Monsterrat island owes its existence to?
the Soufrière Hills stratovolcano
How long has the Montserrat volcano been dormant for?
For over four centuries
When did Montserrat suddenly burst back to life?
July 2005
Between 1995 and 2005 how much magma did the volcano in Montserrat spew out?
nearly 0.5km3 of magma
What were the principal hazards of the Montserrat oufrière Hills stratovolcano?
pyroclastic flows, tephra falls, debris avalanches and occasional lava flows
When did eruptive activity peak in Montserrat? and what happened?
1997, when 19 people were killed and Plymouth, the islands capital, was destroyed by pyroclastic flows, fires and tephra deposits
What was the basic cause of the Montserrat volcano?
Atlantic plate colliding with Caribbean plate
What was the basic cause of the Montserrat volcano?
g
What were the human causes of the Montserrat volcano?
- Developing country with little technology
- Poor country
- Relatively high population density
- Bulk of communications radiated from main volcanic area
- Capital and airport too near volcano
What were the environmental impacts of the Montserrat volcano?
- Volcanic dust caused silicosis and asthma
- Coral reefs buried in ash/dust
- Cloud forest destroyed
- Acute acid rain
- Lakes with pH 1.5 = death of aquatic life
What were the social impacts of the Montserrat volcano?
- 19 deaths (all farmers)
- Southern 60% of island left inhabitable – loss of homes
- 50% of population went to UK or USA
What were the economic impacts of the Montserrat volcano?
- Airport destroyed
- Capital (Plymouth) buried under 12m deep mudflow
- Loss of main roads, homes and other infrastructure
- Loss of main flat fertile farm area with its cash crops
- Loss of once large tourist trade
What were the short term responses to the Monserrat volcano?
- Evacuation to safer north
- Exclusion zone set up (60% of island)
What were the long term responses to the Monserrat volcano?
- 1988: UK granted residency rights in UK to islanders
- UK launched three year $122 million reconstruction programme
- EU gave $12 million relocating capital to Brades estate
- New airport opened in 2005
- Increased monitoring of volcano
- Decline of once prosperous island
- House building and diversification of economy into services
What happened to Monsterrat’s population?
- Montserrat’s population, which stood at 10,728 in 1990, plummeted to just 6409 by 2000
- Out-migration was a social and economic disaster
o It undermined the islanders sense of community and a disproportionate number of better educated islanders (especially young women left)
What happened to Monsterrat’s population?
- Montserrat’s population, which stood at 10,728 in 1990, plummeted to just 6409 by 2000
- Out-migration was a social and economic disaster
o It undermined the islanders sense of community and a disproportionate number of better educated islanders (especially young women left)
What is an example of a volcanic eruption in an MEDC?
Mount St Helens, USA, May 1980
Where is mount St Helens?
Washington State
What was the basic cause of Mount St Helens?
Pacific plate colliding with North American Plate
Physical causes of Mount St Helens
- Level 5 volcano
- Landslide = lateral blast
- Pyroclastic flow
- Vast ash cloud
- Snow melt = lahars
When was Mount St Helens eruption?
May 1980
What were the human causes of Mount St Helens eruption?
- National park so largely ignored
- Wildness meant few roads
- Very low population so often difficult to find
- Bridges vulnerable to flash floods
What were the impacts like from Mount St Helens, May 1980?
- 2 month warning build up and very closely monitored
Knew past historical pattern of eruptions
What were the environmental impacts of Mount St Helens?
- Fish killed in hot, choked rivers
- Wildlife wiped out, e.g. 5000 deer
- Thousands of trees blasted over 600km2
- 540 tonnes of ash fell on 60,000 km2
What were the social impacts of Mount St Helens?
- 57 killed
- 200 homes lost
- Little stress/shock recorded
What were the economic impacts of Mount St Helens?
- US $3 billion damage
- Ash made roads slippery
- Lahars blocked roads
- Crops destroyed, as ash chocked pores in leaves of plants
- Closed navigation on Columbia river
- 47 bridges destroyed
- 300km of roads blocked
- Visibility poor for 2 weeks, forcing airports to shut
- Ash caused power cuts and black outs
Were the responses to Mount St Helens eruption effective?
Effective, as hazard was known and expected
What were the short term responses to Mount St Helens eruption, May 1980?
Search and rescue but area already evacuated
What were the long term responses to Mount St Helens eruption, May 1980?
- Clean-up cost of $63 million
- Increased tourism – as now nationally known
- Increased employment during clean up
- US forest service took over area as a National Volcanic Monument
- Long-term monitoring and research
