Plate Tectonics Flashcards
Evidence of the plate tectonic theory…
Geology (mountain ranges match Europe and North America)
Fossil Records (Mesosauraus found in South African and Brazil)
Climatology (coal deposits found in North America and Europe, glacial deposits found in Africa, India, Australia..)
Living Species (Earthworms found in New Zealand, Asia and North America)
Palaeomagnetism
Lithosphere
The crust and upper mantle. (100 km thick)
The zone where tectonic plates are formed.
Athenosphere
A layer of soft, almost plastic like rock. (150 km thick)
Moves very slowly carrying the lithosphere on top.
Inner core
Solid ball containing lots of iron and nickel.
Outer core
Semi-molten and also contains lots of iron and nickel.
Continental crust
30-70 km thick
less dense
Oceanic crust
6-10 km thick
more dense
Who thought either side of the Atlantic ‘fitted together’?
Francis Bacon
Who proposed the theory of continental drift?
Alfred Wegener
What year was continental drift proposed?
1912
Name of the once supercontinent?
Pangea
Land forms at a constructive plate margin
Mid-ocean ridge
Rift valley
Land forms at destructive plate margin
Oceanic-Continental: ocean trench, volcanic arc, fold mountains
Oceanic-Oceanic: ocean trench, island arcs, volcanoes
Continental-Continental: fold mountains (no volcanoes)
Land forms at conservative plate margin
Low ridges and shallow focus earthquakes
Example of a hot spot
Hawaiian Islands
Types of volcanoes
Dome volcano, Shield volcano, Composite cone and Caldera
Balsatic lava
Along mid-ocean ridges
Over hotspots
Alongside rift valleys
CONSTRUCTIVE
Adesitic lava
Island arcs
DESTRUCTIVE
Rhyolitic lava
DESTRUCTIVE
Primary effects of eruption
Volcanic gases
Lava flows
Tephra (rock fragments and particles ejected by a volcanic eruption)
Pyroclastic flows
Secondary effects of eruption
Climate change Flooding Lahars (a destructive mudflow on the slopes of a volcano) Tsunamis Volcanic landslides
Minor forms of extrusive activity
Geysers
Fumaroles
Hot springs/ boiling mud
Intrusive land forms
Dykes
Sills
Laccoliths
Batholiths
Other possible causes of earthquakes
Reactivation of old fault lines
Subsidence as a result of deep mining
Pressure on surface rocks from water in large reservoirs
Focus
the point within the crust where the pressure release occurs
Epicentre
is directly above the focus on the surface of the ground
Seismic waves that travel through the interior of the Earth
P (primary) waves
S (secondary waves
The two types of surface waves
Love waves
Rayleigh waves
Primary waves
fastest wave
moves through solid rock and fluids
5000 meters per second through granite
Secondary waves
only moves through solid rock
half as fast
Love waves
travel on Earth's surface most destructive slowest wave travel globally only travels through solids
Rayleigh waves
rolls over the ground like waves does over ocean
most shaking is due to this wave
travels through liquids and solids
Richter scale
measure magnitude
it is logarithmic- each value is 10 times greater than previous value
1-9+
Mercalli scale
measures the impact
using observations
1-12
Characteristics of a tsunami
Wave height is low (under 1 m) Reaching shore it rises (over 25 m) Wavelength is very long (100-1000km) Travel very quickly (640- 960 kmph) Series of waves Wave period is long (10- 60 minutes)
Predicting when and where of an earthquake
currently impossible to predict when but strange animal behaviour and small tremors, cracks can suggest
Earthquake warning system can detect P waves
Possible to predict where future earthquakes may happen using data from past earthquakes
Protecting people from earthquakes
Buildings can be designed to withstand earthquakes e.g. reinforce concrete
Construction laws have become stricter
Planning for an earthquake
Educating people about what to do and how to evacuate
Training emergency services
Predicting when and where a volcano eruption
Possible to predict as change in shape and small tremors can mean eruption is likely
Can not predict exact date
Protecting people in volcanic eruption
Buildings can be strengthened so less likely to collapse due to weight of ash
Divert the lava flow using a barrier
Planning people for a volcanic eruption
Future developments can be planned to avoid areas at most risk
Predicting where and when a tsunami hits
Tsunami warning systems rely on earthquake detection systems
Tsunami warning centres around the world
Protecting people from tsunamis
Buildings designed with raised and open foundations and made strong
Tsunami walls
Planning for a tsunami
Training emergency services
Governments plan evacuation routes
Educating people on what to do and how to evacuate
Factors that increase the severity of the impacts of a volcano…
Development of a country
Population
Timing
Deaths in L’Aquila earthquake
300
Deaths in Port au Prince earthquake
Between 230,000 and 250,000
How many homeless in L’Aquila
70,000
How many homeless in Haiti
1.5 million
Responses in L’Aquila
12,000 rescue and support workers
Mortgage payments and gas and electricity bills suspended
Bye end of 3009, 4500 new buildings built
Date of L’Aquila
6th April, 2009
Date of Haiti
12th January, 2010
Responses to Haiti
810,000 placed in aid camps
16,000 UN troops to restore law and order
$100 million by USA
Magnitude of L’Aquila
6.3
Magnitude of Haiti
7
Number of countries affected by Indonesia
14
Number of deaths of Indonesia
230,000
Number of deaths for Japan
25,000
Height of Indonesia
39m
Height of Japan
24m
Damage to which Japan nuclear plant
Fukushima
Date of Montserrat
25th June,1997
Date of mt St. Helens
18th may, 1980
Number of deaths of Montserrat
19
Number of deaths at mt St. Helens
56
Cost of damage at Montserrat
£1 b
Cost of damage at mt St. Helens
$1.1 b
Reptile form in Africa and South America
Mesosaurus
Fossil plant found in all continents
Glossopteris
Name of Rift Valley
East African Rift Valley
Date wegener published his theory
1912
