EQ1: 1.3 Flashcards by Isabelle Butcher

Describe P waves

Fastest so they’re the most destructive, arrive first, have a short wavelength, little wave motion
Compression wave

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Describe S waves

Arrive seconds layer, longer wavelength

Up & down motion

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Describe love waves

side to side movements

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What is the Mercalli Intensity scale?

Concerned with damage done on people & environmemt

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What plate boundary have the highest magnitude?

Convergent plate boundary

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What plate boundary has the second highest magnitude?

Conservative plate boundary

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Just because an earthquake has a high magnitude doesn’t mean it has a high death toll because…

Depends on how developed the country is

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What are the primary effects of earthquakes?

Ground shaking

Crustal fracturing

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What are the secondary effects?

Soil liquefaction
Landslides
Tsunamis

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Crustal fracturing process

Changes earth’s surface caused by tectonic forces - cracks in crust

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Soil liquefaction process

saturated soil loses strength in response to stress - soil behaves like a liquid

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Landslides process

Mass movement - triggered when particles weaken due to shaking during earthquakes

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Tsunamis process

Shaking - water column displacement - water above to rise - only ocean plate

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What is a tsunami?

series of larger than normal waves - caused by volcanic eruptions or underwater earthquakes

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What is the formation of a Tsunami?

Plate shifts abruptly - causing earthquake - triggers wave
Waves move in all directions - as fast as 600mph
Waves hit shallower water - compress - speed slows - builds height
Wave height increases & currents intensify - becoming a threat

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We wouldn’t see a tsunami if…

The seabed didn’t get higher but it does

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Explain Water Column Displacement

Body of water at subduction zone has been displaced & is on the move

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Name primary impacts of an earthquake

Deaths

Homes destroyed

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Name secondary impacts of an earthquake

People missing

Financial cirsis

Short term impacts of an earthquake

Deaths
Buildings destroyed
Property gone

Long term impacts of an earthquake

People missing
Financial crisis
Loss of jobs

Name tsunami impacts

Reliance on aid - relying on another country
Debry in water - many die
Lack of aid - inadequate healthcare
Lack of warning - no one had time to prepare
Missing people put on notice board - not social media
Holidays - many tourists - language barriers

What are the primary impacts of volcanoes?

pyroclastic flows, tephra, lava flows, volcanic gases

What are the secondary impacts of volcanoes?

lahars, jokulhlaups

What is Pyroclastic flow?

Dense fast-moving flow of solidified lava pieces, volcanic ash, and hot gases

What is Pyroclastic flow caused by?

Column of lava, ash & gases - loses its momentum

Give an example of this

eruption of mount Pelee on the island of Martinique May 8th 1902

What is a tephra?

Anything on surface of volcano and goes up in air then comes back down, these are glassy particles - cooling of droplets of magma, they're cool cos they're from a cool place like a mountain or Antartica

What is a tephras origins

explosive volcanic eruptions

What are a tephras harmful effects?

causes physical damage on vegetation - altering capacity to exchange gas, water and heat with atmosphere of a chemical effect e.g. nutrient input or acidification on sensitive soils

Give an example of this

Brow Bluff, Antartica (2016) Ice cloud - Atlantic eruptions

What are lava flows?

magma cooling fast to turn into solid - can cause slab pull

What are lava flows origins?

streams of molten rock that pour or ooze from an erupting vent

What are its harmful effects?

hot - cause severe burns & burn down vegetation & structures and has enormous amounts of pressure - crush or burn anything whatever survives being burnt

Give an example of this

Red Hot basaltic lava flow - Hawaii

What are volcanic gases?

given off by active or dormant volcanoes and gases trapped in cavities in volcanic rocks, dissolved gases in magma & lava - from volcanic craters or vents

What are the origins of volcanic gases?

primordial & recycled constituents from the earth's mantle

What are their harmful effects?

breathing air with more than 3% of CO2 - headaches, dizziness, increased heart rate & difficulty breathing and 15% of CO2 causes death

Give an example of this

volcanic rocks

What are lahars?

like wet concrete - flow down the slopes of volcanoes or down river valleys at rapid speeds - similar to fast-moving streams of water

What are lahars origins?

Javanese origin

What are its harmful effects?

cause serious economic & environmental damage to river valleys & flood plains. they crush, abrade, bury (buildings, valuable land) or carry anything away

Give an example of this

1991 eruption of Mt.Panatubo, Philippines

What are Jokulhlaups?

large landscape impact, flood volume & peak discharge, can erode gorges & spillways, dry waterfalls, streamlined obstacles, scour marks & longitudinal grooves

What are its origins?

glacial outburst floods that occur frequently at many locations in Iceland

What are its harmful effects?

melting creates glacial lakes - violently burst - resulting floods devastate downstream communities, many live in shadows of glacier

Give an example of this

Himilayas, the Andes & Swiss Alps, Iceland