Earth's Structure and the 2011 Tsunami

The crust is the outermost layer, varying in thickness from 5-10km beneath the ocean.
The mantle is the widest layer, spanning 2,900 km.
The mantle's heat and pressure cause the rock to be in a liquid state, undergoing convection.
The inner and outer core are the hottest section of the earth, reaching 5,000 degrees.
The core is primarily composed of iron and nickel, being four times denser than the crust.
The inner core is solid, while the outer core is liquid.

The 2011 Tohoku earthquake and tsunami resulted from a 9.0 magnitude undersea earthquake off the coast of Japan.
The earthquake occurred at a destructive plate boundary where the Pacific plate subducts beneath the North American plate.
The epicenter was approximately 72 km east of Honshu.
Destructive tsunami waves, reaching up to 37.9 meters in height, struck Japan minutes after the earthquake.
The tsunami traveled up to 6 miles inland, causing extensive damage and loss of life.
The disaster resulted in 20,000 deaths and 2,500 missing persons.
The economic damage reached approximately £189 billion.
The Japanese government issued tsunami warnings and ordered evacuations along the Pacific coast.
Residents within a 20 km radius of the Fukushima I Nuclear Power Plant were evacuated.
Temporary accommodation was provided to address homelessness.

Ash clouds consist of small pieces of pulverized rock and glass ejected into the atmosphere.
Volcanic gases include sulfur dioxide, water vapor, and carbon dioxide released from the volcano.
Lahars are volcanic mudflows that often flow down valley sides of the volcano.
Pyroclastic flows are fast-moving currents of superheated gas and ash, reaching temperatures of 1,000°C and traveling at speeds of 450 mph.
Volcanic bombs are thick, viscous lava fragments ejected from the volcano.

Earthquakes occur when two tectonic plates become locked, resulting in a build-up of friction.
The accumulated stress causes the plates to eventually move into a new position, releasing energy in the form of seismic waves.
Seismic waves travel from the focus, the point where pressure is released, towards the epicenter.
The epicenter is the point directly above the focus where seismic waves reach first.

The focus is the point at which pressure is released during an earthquake.
The epicenter is the point directly above the focus, where seismic waves reach first.
Seismic waves are energy waves that travel outwards from the focus.

The Earth's crust is the outermost layer, varying in thickness (5-10 km beneath the ocean).
It's made up of several large plates.
The mantle is the widest layer (2900 km thick).
Heat and pressure in the mantlet cause the rock to be in a liquid state that's in a state of convection.
The inner and outer core is the hottest section (5000 degrees).
Mostly made of iron and nickel, 4x denser than the crust.
The inner core is solid, the outer core is liquid.

Radioactive decay of elements in the core and mantle generate heat.
Heated lower parts of the asthenosphere become less dense and rise.
As they move upwards, they cool down, become more dense, and sink.
These circular movements of semi-molten rock are convection currents.
Convection currents create drag on the base of tectonic plates causing them to move.

Shield - Made of basaltic rock, form gently sloping cones from layers of runny lava.
- Located at hotspots and constructive margins.
- Gentle and predictable eruptions.
Composite - Most common type found on land, created by layers of ash and lava.
- Located at destructive margins.
- Explosive and unpredictable eruptions due to the build-up of pressure within the magma chamber.

Ash Cloud - Small pieces of pulverised rock and glass thrown into the atmosphere.
Gas - Sulphur dioxide, water vapour and carbon dioxide come out of the volcano during eruptions.
Lahar - Volcanic mudflow that runs down valley sides on a volcano.
Pyroclastic Flow - Fast-moving current of superheated gas and ash (1000°C).
- Travels at 450 mph.
Volcanic Bomb - Thick lava fragment ejected from the volcano.

Destructive Plate Margin - Denser plate subducts beneath the other, friction causes it to melt and become molten magma.
- Forms volcanoes and devasting earthquakes.
Constructive Plate Margin - Two plates move apart, causing new magma to reach the surface.
- Forms volcanoes and submarine mountain ranges.
Conservative Plate Margin - Two plates slide past each other.
- Causes earthquakes.

Earthquakes happen when two plates become locked causing friction to build up.
The pressure is eventually released, triggering the plates to move into a new position.
This movement causes energy, in the form of seismic waves, to travel from the focus towards the epicentre.
This causes the crust to vibrate triggering an earthquake.

Focus - The point at which pressure is released.
Epicentre - The point directly above the focus where the seismic waves reach first.

Shallow Focus - Usually small and common.
- Seismic waves spread and cause damage over a wide area.
Deep Focus - Occur on destructive margins.
- Seismic waves travel vertically, damage is localized.

Caused by a 9.0-magnitude earthquake off the coast of Japan.
The earthquake occurred at a destructive plate boundary where the Pacific plate subducts below the North American plate.
Generated devastating tsunami waves of up to 37.9 meters, causing widespread damage and loss of life.
The Fukushima I Nuclear Power Plant was evacuated.
20,000 deaths, 2,500 missing, £189 billion in damage.