Tectonic

Geophysical

caused by internal earth processes

Hydro-meteorological

caused by atmospheric, hydro-logical or oceanographic processes

Tectonic Hazards

Earthquakes, volcanoes + other geophysical events that happen somewhere a risk is caused (near ppl)

Inner core

solid

Outer core

liquid

Mantle

molten

Crust

solid

Oceanic plate

dense, compact, basalt

Continental plate

not dense, thick , granite

Acid Lava

Thick viscous lava which flows short distances

Basic Lava

Thin , runny lava which can flow long distances

Composite Volcano

Steep sided cone with layers of ash and lava

Compressional Margin

This is where two plates move together

Core

The centre of the earth

Mantle

The molten rock that surrounds the earth's core

Crust

The thin layer of the earth's surface

Crater

The mouth of the volcano

Earthquake

A shaking of the earth's crust

Epicentre

The point within the earth's crust where the earthquake occurred

Focus

The point on the earth's surface directly above the epicentre

Fold Mountains

Mountains formed by the earth's movements

Geosynclines

A depression between two plates

Lava

The name given to liquid magma when it reaches the surface of the earth

Richter Scale

This measures the strength of the earthquake

Shield Volcano

A gentle sided volcano with a wide base made up of basic lava (basaltic) effusive (less explosive) that flows fast on a constructive plate boundary eg. Mount Kea

Subduction Zone

Where a oceanic plate sinks and slides under continental plate leads to earthquakes eg. Indian Ocean 2004 Tsunami

Tectonic Plate

A huge section of the earth's crust

Tensional Margin

Where two plates move apart

Tsunami

Huge tidal waves that are caused by submarine earthquakes

Vent

The opening through which the lava flows in a volcano

Volcano

A cone shaped mountain created by lava and ash being erupted from the earth

Destructive/convergent

1. Oceanic and continental crust move towards each other

2. Oceanic crust subducts (pushed under) as it is more dense

3. Oceanic melts into mantle, gets stuck, tension released= earthquakes

constructive/divergent

1: plates pulled apart

2: magma rises + forms new crust

4: sea floor spreading occurs

Transform/conservative

1: plates slide past each other

2: no volcanoes- bad earthquakes

Collision/ destructive

1: 2 continental plates move towards each other

2: push up to create fold mountains

How far does the East Africa rift extend?

3000 km + 0.5 cm per year

What volcanoes are on the East African rift?

Mount Kilimanjaro, Mount Kenya, Mount M

Strato volcano

steep, destructive plate boundary, thick (high viscosity) lava, ash, andesite, eg. Soufriere often caldera

Caldera

crater in volcano caused by blowing top off

Intra-plate earthquake

occurs in middle of plateeg. Gujarat India 2001

Inter-plate earthquake

at plate boundary

Hotspots

place in mantle that is hotter than rest causes volcano as land moves over it (not on plate boundary) eg. Hawaiian islands

Alfred Wegener

theorised pangea and ridiculed

Convection currents theory

1)rock heated by core

2)hot rock rises to crust

3)rock cools + sink to core

4)warms up +repeats

Wilson cycle

1) Constructive plate pulls apart

2) new oceanic crust rises (dense)

3) sea floor spreads

4) oceanic crust will eventually subduct the continental crust + close sea floor

Sea floor spread

constructive pulls apart, magma rises + solidifies, widens sea floor

Ridge push

magma rises as plates move apart then cools to form new plate material cools (becomes denser) and slides down away from ridge causing other plates to move

Slab pull

denser plate slips back into mantle due to gravity and pulls rest of plate with it

Locked fault

plates get stuck

Benioff zone

where subduction zones are that often have earthquakes up to 670km eg. Peru Chile trench

Biggest earthquake?

9.1 Magnitude Indonesia 2012

Paleomagnetism

study of the record of Earth’s magnetic field in rocks- minerals lock in direction + intensity of field when formed

What is step one of the eruption process?

Underground rocks melt become less dense (than solid rock) and rise

What is step two of the eruption process?

Rising magma collects in underground chambers building pressure over time (due to magma + gases eg, H2O + CO2)

What is step three of the eruption process?

Too much pressure= eruption

What is step 4 of the eruption process?

Pressure may force magma through cracks in crust leading to eruption- happen in cracks or fissures where stuff thrown out

Pyroclastic flow

On strato: Dense cloud of volcanic ash+gas flows down steep side of volcano 400°C at ≥100km/h

Pyroclastic flow example

French Caribbean island of Martinique- Mount Pelèe 1902

Mount Pelèe 1902 pyroclastic flow impact

incinerated Saint-Pierre killing nearly 29,000

Gases

Strato and shield: SO₂, H20, CO2= climate change + breathing problems

Volcano gases eg.

1991 eruption of Mt Pinatubo in Philippines

1991 gases of Mt Pinatubo in Philippines impact

250 megatons atmo climate change

Lahar

shield + strato: Water + lava = concrete like mudflow

Lahar eg.

Nevado del Ruiz in Columbia in 1985 (killed 20,000 + town of Amero)

Tephra (ash cloud)

shield + strato: climate change, breathing problems, contaminate water, transport issues

tephra eg.

1980 Mount St. Helens US, Washington (1000 flights cancelled)

Lava flows

shield + strato: fast flow of lava- fixed items burn, 10km/h

Lava flows eg.

Kīlauea volcano engulfed Kalapana 1986-90 destroy 100 residences

Jokulhlaups

shield + strato: glacial poutburst flows- volcano explodes beneath ice-cap

Jokulhluap eg.

1996, Iceland, Gjálp (erupted) destroyed parts of main road

Volcanic bombs

shield + strato: partially molten chunks of rock thrown from volcano

VEI

Volcanic Explosivity Index from 0-8

Tsunami step 1

Usually at destructive plate boudary

Tsunami step 2

Oceanic + continental plates move towards eachother

Tsunami step 3

Friction= locked fault in subduction zone where thedense oceanic is pushed under

Tsunami step 4

Pressure builds

Tsunami step 5

‘thrust’ of plates as unlock = earthquake

Tsunami step 6

land rebounds upwards near trench pushing column of water up and out

Fumaroles

vent releases hot gases not liquid/solid

Tsunami Time Travel Map (TTT map)

gives idea of how event may occur with risks and time so preparations can happen

RIMES

Regional Integrated Multi-hazard Early warning System for Africa + Asia

When was the (Boxing Day Tsunami)?

26/12/2004

Where was the epicentre (Boxing Day Tsunami)?

North West of Indonesia