Geography - Earthquakes and Volcanoes

constructive/ divergent plate boundary

when 2 plates move apart, allowing magma to rise and create new land/ crust (mid oceanic ridge), often resulting in volcanic activity and earthquakes.

destructive/ convergent plate boundary

when oceanic and continental plates collide. oceanic heavier/ denser so it is forced beneath continental, forming subduction zone.

friction and pressure built up can cause earthquakes, volcanic activity, and the formation of mountain ranges.

oceanic plate melts, leading to magma formation that can result in volcanic eruptions.

collision/ convergent plate boundary

when two continental plates collide, since neitehr can be destroyed, they are forced up against eachother forming mountain ranges.

conservative/ transform

when 2 plates slide past eachotherhorizontally, causing friction that can lead to earthquakes. This boundary type does not create or destroy crust.

why do people live near earthquake prone areas?

• poverty and overpopulation - forced to live on marginal land

• tourism

• cheaper land - housing

• economic opportunities - jobs in industries such as agriculture (coastal areas offer easy access to the sea) and tourism

• infrequent timings of earthquakes - presume that wont occur in their lifetime

• generational residence and cultural ties

hypocentre/ focus

exact location of where earthquake occurs beneath the surface

epicentre

location on the surface that is directly above the focus

secondary hazards caused by earthquakes

• tsunamis

• dam failure

• natural disasters

• landslides

• fire/ wildfires

• disease outbreak

• liquefaction of land

factors that affect earthquake

• duration

• depth of hypocentre

• location

• magnitude

• readiness of people

• time

• geology

• population density of surrounding area

• building conditions - whether they are built strong enough to withstand quake

magma

melted rock in mantle/ under crust

lava

molten rock ejected onto earths surface

vent

long tube/ pipe/ channel inside volcano that transports magma

active volcano

a volcano that has recently erupted

dormat volcano

a volcano that has not recently erupted by is expected to in the near future

extinct volcano

a volcano that is not expected to erupt again

volcanic hazards

• lava flow

• pyrocrastic flow

• lava bombs

• ash clouds

• acid rain

• lahar/ mudflow

why do people live near volcanoes?

• geothermal energy

• rich in minerals - mining jobs

• fertile land - agriculture jobs

• unlikely that volcano will erupt during lifetime

• tourism

what are some ways to minimize the impact of volcanic eruptions?

• lava diversion channels

• mudflow barriers

• stronger infastructure/ buildings to prevent collapse from ash volume

• education

• monitor rise in ground temperatures using heat seeking cameras

• install warning systems

• satellite global positioning systems

• tiltmeters

• train emergency services

• observe volcanic activty such as an increase in gas and steam emissons

• evacuation route - plan

• hazard mapping

• lava cooling - dump water

what are some ways to minimize the impact of earthquakes?

• train emergency services

• epicentre and focus mapping - observe for any patterns in location or time

• install seismometers/ devices that can measure an increase in earth tremors, pressure and release of radon gas

• earthquake drills

• warning and information systems on tv and radio

• educate public

• construct buildings strong enough to withstand

ritcher scale

measures magnitude via seismometer and uses a logarithmic scale

mercalli scale

measures intensity via observation of effects and impacts

hotspots

small areas inwhich magma rises through a plate that glides above

characteristics of a shield volcano

• wide base

• gentler slope

• low height to width ratio

• less violent eruptions

• frequent eruptions

• runny and thin lava

characteristics of a cone/ stratovolcano

• steeper slope

• more violent eruptions

• formed out of layers of lava and ash

• sticky lava consistency - builds up around vent, hence steeper sides

• hazardous - Due to their explosive nature, stratovolcanoes can produce pyroclastic flows, ash clouds, lahars (mudflows), and

causes of japan 2011 earthquake

• eurasian (continental) and pacific (oceanic) plate

• destructive plate boundary

• pacific pushed under eurasian, forming subduction zone

• pressure and friction builds - causing megathrust earthquake

why are volcanoes formed at destructive boundaries?

• At a destructive (convergent) boundary, the tectonic plates are moving towards each other:

  • The heavier, denser oceanic plate subducts under the lighter continental plate

  • In the subduction zone, the two plates come together, causing friction

  • Friction causes heat and the plate material melts, forming magma

  • The magma rises to the surface through cracks in the crust

  • The cooling lava and ash build up, forming a volcano

impacts/ effect of 2011 jp earthquake

• 26,000 injured

• 16,000 dead

• 23,000 displaced

• largescale blackout - 4.4 million households lost electricity

• large amounts of infrastructure destoryed/ damaged

• tsunami

• us $235 billion lost

• nuclear reactor power station meltdown

responses to 2011 jp earthquake

• rescue teams

• financial support from global organsations

• The U.S. provided a significant amount of aid, including search and rescue teams, military assets, humanitarian supplies, and financial assistance.

• medical assitance

• Many countries offered humanitarian aid in the form of medical supplies, food, water, and other essential supplies to support those affected by the disaster.

causes of the 2010 e15 eruption

• constructive plate boundary

• north alantic and eurasian plate

• several magma chambers combined to make a heavy amount of magma below surface

impacts of the e15 eruption

• substanial ash cloud

• infastructure damaged

• airline suspended services due to ash cloud

• crops destoryed

• billions lost in revenue due to flight delays

• cancelled sporting events

• floods

• water supply contaminate

• airline shares plummeted in price

• food imports pauses which impacted industries

responses to e15 eruption

• rescue teams sent

• food provision

• mass evacuation

• physcological support

explain why it is necessary to provide clean water and sanitation after an earthquake

People need clean water supply/water to drink/to live/survive/prevent dehydration [1]

Water/sewage pipes/water treatment stations will be cut off/damaged/broken [1]

No running water [1]

People cannot wash/bath/shower [1]

No flush toilets [1] sewage will spill out/contaminate (water supplies/area) [1]

Disease/germs from dirty/polluted water or people sick from dirty [1] water/waterborne

diseases/examples of such as cholera [1]