Tectonic Science Summary
Tec
Created by Stephen Harden-Wilson
02/01/22 Volcanoes haz
Prim
The types of volcano… eve
Plate Boundaries Shield volcanoes: high temperatures, basaltic magma, low explosivity Sec
There are 3 plate boundaries that each have a different movement, resulting in different associated hazards. Stratovolcanoes: lower temps, andesitic or rhyolite magma, very explosive res
Their according types of magma…. Features of a Volcano… Primary
TYPE IMAGE HAZARDS Gases: water vapour, carb
dioxide – these can accum
Divergent Shallow focus low magnitude earthquakes Tephra: fragments of rock
Shield volcanoes w/ low explosivity atmosphere
Pyroclastic Flows: Hot ga
Convergent Large violent earthquakes ejected from the vent at 1
Secondary
Stratovolcanoes of high explosivity Jokulhaups: rapid glacial
Collision zone (2 continental plates) forms heat that causes muddy fl
mountain ranges and plateau w/ wide shallow EQ Lahars: volcanic mudflow
zone from the volcano that can
Volcanoes have an activity status which runs from Active -> Dormant -> Extinct. This
Conservative Because one plate moves faster than the other,
upon after careful scientific analysis.
rocks can be ripped which causes earthquakes
Benefits of Volcanism?
Plate Theory 1. Geothermal springs can be harnessed for energy
2. Old lava holds materials that can be used for industry
1. Mid-Ocean Ridges
3. Basaltic soils are very fertile due to potassium and phosphorous content
At divergent plate boundaries, the ocean floor swells due to rising convection currents in
4. They create dramatic landscapes that boost tourism
the mantle. The magma it brings fills gaps between the two plates, creating a mid ocean
Predicting Volcanoes
ridge.
They emit precursor activity which can be detected by various instruments. This mean
2. Palaeomagnetism
be detected before it happens, allowing for time to implement emergency response p
This proves that mid ocean ridges spread over time. The new magma cools and “saves” a
Bulging of volcano – tiltmeters, Gas release – aircraft monitoring, Heat increase – th
record of the Earth’s polarity at its time. As Earths polarity switches every 300,000 years,
3.
this record was found to be symmetrical either side of a mid-ocean ridge.
The Layers of the Earth 4. Driving forces behind plate movement
Earthquakes the release of energy from the slow build up of stress in rocks, sent out as rad
Types of seismic waves… The depth of EQs are classed as…
Convection currents are what drive the movement of Shallow: 0-70km
the plates. Currents in the transfer heat from the core The 1st wave, moving
Intermediate: 70-300km
fast in rock and liquid -
to the mantle – liquid rock rises and the cools and falls. > push, pull movement Deep: 300-700km
This creates a convection cycle. (see bottom left!) What happens during an EQ?
5. Intra-Plate Activity Slower than the P Plate movement causes a build-up of tectonic strain (s
Sometimes tectonic activity occurs within a plate, far wave, and has an When this pressure exceeds the strength, the rock frac
opposite up, down releases energy. This is radiated as seismic waves.
from boundaries – this is explained by… movement EQs are measured on the moment magnitude scale/MM
a. Post glacial rebound – land rises after under glacier
more powerful than the previous.
b. Plate compression – large stresses Only moves through
The Wadati-Benoiff Zone is the area of a subduction zo
c. Ancient fault lines – sometimes activate the crust, rolling
motion in the ground Earthquakes are frequent.
d. Mid-ocean ridges – can trigger seismic waves Secondary Hazards of Earthquakes…
6. Hot Spot Volcanism Also only goes through Landslides and Avalanches
Caused by a mantle plume – a localised pocket of the crust, with a high Land Liquefaction: where soil behaves like liquid becau
magma that cause bulging of crust (result of unequal amplitude which makes saturated small soil particles float
vibrates horizontally Tsunamis: where an under-sea EQ displaces a large col
heat output from core). They create shield volcanoes,
radiates outwards as large waves.
and can create island chains over time as plates move.
Tec
Created by Stephen Harden-Wilson
02/01/22 Volcanoes haz
Prim
The types of volcano… eve
Plate Boundaries Shield volcanoes: high temperatures, basaltic magma, low explosivity Sec
There are 3 plate boundaries that each have a different movement, resulting in different associated hazards. Stratovolcanoes: lower temps, andesitic or rhyolite magma, very explosive res
Their according types of magma…. Features of a Volcano… Primary
TYPE IMAGE HAZARDS Gases: water vapour, carb
dioxide – these can accum
Divergent Shallow focus low magnitude earthquakes Tephra: fragments of rock
Shield volcanoes w/ low explosivity atmosphere
Pyroclastic Flows: Hot ga
Convergent Large violent earthquakes ejected from the vent at 1
Secondary
Stratovolcanoes of high explosivity Jokulhaups: rapid glacial
Collision zone (2 continental plates) forms heat that causes muddy fl
mountain ranges and plateau w/ wide shallow EQ Lahars: volcanic mudflow
zone from the volcano that can
Volcanoes have an activity status which runs from Active -> Dormant -> Extinct. This
Conservative Because one plate moves faster than the other,
upon after careful scientific analysis.
rocks can be ripped which causes earthquakes
Benefits of Volcanism?
Plate Theory 1. Geothermal springs can be harnessed for energy
2. Old lava holds materials that can be used for industry
1. Mid-Ocean Ridges
3. Basaltic soils are very fertile due to potassium and phosphorous content
At divergent plate boundaries, the ocean floor swells due to rising convection currents in
4. They create dramatic landscapes that boost tourism
the mantle. The magma it brings fills gaps between the two plates, creating a mid ocean
Predicting Volcanoes
ridge.
They emit precursor activity which can be detected by various instruments. This mean
2. Palaeomagnetism
be detected before it happens, allowing for time to implement emergency response p
This proves that mid ocean ridges spread over time. The new magma cools and “saves” a
Bulging of volcano – tiltmeters, Gas release – aircraft monitoring, Heat increase – th
record of the Earth’s polarity at its time. As Earths polarity switches every 300,000 years,
3.
this record was found to be symmetrical either side of a mid-ocean ridge.
The Layers of the Earth 4. Driving forces behind plate movement
Earthquakes the release of energy from the slow build up of stress in rocks, sent out as rad
Types of seismic waves… The depth of EQs are classed as…
Convection currents are what drive the movement of Shallow: 0-70km
the plates. Currents in the transfer heat from the core The 1st wave, moving
Intermediate: 70-300km
fast in rock and liquid -
to the mantle – liquid rock rises and the cools and falls. > push, pull movement Deep: 300-700km
This creates a convection cycle. (see bottom left!) What happens during an EQ?
5. Intra-Plate Activity Slower than the P Plate movement causes a build-up of tectonic strain (s
Sometimes tectonic activity occurs within a plate, far wave, and has an When this pressure exceeds the strength, the rock frac
opposite up, down releases energy. This is radiated as seismic waves.
from boundaries – this is explained by… movement EQs are measured on the moment magnitude scale/MM
a. Post glacial rebound – land rises after under glacier
more powerful than the previous.
b. Plate compression – large stresses Only moves through
The Wadati-Benoiff Zone is the area of a subduction zo
c. Ancient fault lines – sometimes activate the crust, rolling
motion in the ground Earthquakes are frequent.
d. Mid-ocean ridges – can trigger seismic waves Secondary Hazards of Earthquakes…
6. Hot Spot Volcanism Also only goes through Landslides and Avalanches
Caused by a mantle plume – a localised pocket of the crust, with a high Land Liquefaction: where soil behaves like liquid becau
magma that cause bulging of crust (result of unequal amplitude which makes saturated small soil particles float
vibrates horizontally Tsunamis: where an under-sea EQ displaces a large col
heat output from core). They create shield volcanoes,
radiates outwards as large waves.
and can create island chains over time as plates move.
