Tectonics

Epicenter

Epicenter

Point on Earth's surface directly above an earthquake's focus, where shaking is strongest

Focus

The point where the plates slip, and from where the seismic waves radiate outwards

After shocks

Smaller earthquakes that occur after the main event, caused by the plates slipping a little more as they settle into their new configuration

seismic waves

Energy waves that radiate out from the focus and cause the ground to shake.

What is a volcano

An opening in the earths crust from which molten rock and gas is ejected into the atmosphere and onto the Earth surface. a very large crater is known as a caldera

Vent

The pipe that connects the magma chamber to the crater magma rises up the vent before erupting

Crater

A depression at the summit of the volcano came from which lava ash and other products are emitted

Parasitic cone

A smaller come that develops on the side of the main cone it forms if the main vent is blocked and rising magma follows a smaller channel to be erupted from the flank (side) of the volcano

Magma chamber

A reservoir of molten rock within the crust below a volcano when this starts to rise towards the surface and eruption becomes more likely

Active

A volcano that has erupted in the past 10,000 years

Dormant

A volcano that has not erupted in the past 10,000 years but has the potential to erupt again

Extinct

A volcano that has lost the potential to erupt because it has been cut off from a source of rising magma

What is a shield volcano

Found on constructive margins, low viscosity, high temperature, gentle and frequent eruptions

What is a stratovolcano

found on destructive margins, acidic lava, high viscosity, low temperature, explosive powerful eruptions

Constructive margin

Two oceanic plates are diverging, magma rises through gap between two plates causing volcanoes, along the mid Atlantic Ridge, usually underwater forming mid ocean ridge, eruptions are usually gentle

Distructive margin

One oceanic plate and one Continental are converging, oceanic plate is subducted under the Continental plate because it is denser, continental crust goes up creating a range of fold mountains

Collision margin

Two continental plates converge, creating fold mountains, very powerful earthquakes occur

Conservative margin

Two plates move alongside, friction can cause the plates to stick and pressure builds up, resulting in powerful earthquakes

In the structure of the earth, where do the denser substances go?

Sink to the middle

In the structure of the earth, where do the less dense substances go?

Float to the top

What is a tectonic plate margin

The line where 2 adjacent tectonic plates meet

What is the lithosphere?

crust and upper mantle

What is oceanic crust?

the relatively thin part of the earth's crust that underlies the ocean basins

What is continental crust

the relatively thick part of the earth's crust that forms the large landmasses.

Where can most earthquakes be found

Destructive margins surrounding the pacific ocean

Where are volcanoes found

Destructive and constructive plate margins

What is the Pacific Ring of Fire?

A belt of volcanoes that circle the ocean

What is a hotspot volcano?

a volcano that does not occur near a plate boundary

What is a primary earthquake hazard

Ground shaking and displacement caused by seismic waves

What are the secondary earthquake hazards

Landslides and avalanches, liquefaction, quake lakes, tsunamis, buildings can collapse

What is the inner core?

1260km thick made of solid iron and nickel and is the most dense substance in the earth

What is the outer core?

2200km thick and made of molten iron and nickel

What is the mantle

2900km thick and denser than the crust (the upper mantle is rigid and the lower mantle is semi- molten)

What is the crust?

The thinnest layer and lowest density layer

Volcanic Hazards

Ash, carbon dioxide, climate change, lava bomb, lava flow, pyroclastic flow, tephra, lahar, jokulhlaup

What are the reasons for living in volcanic areas

Easy to grow crops, heat from volcanoes can generate hot water and electricity, valuable materials such as sulphur, tourism

Reasons for living in seismic areas

Other benefits compensate for the risks, such as good jobs and lifestyle in coastal California

How many major tectonic plates are there

7

How many minor tectonic plates are there

13

Why do tectonic plates move

convection currents

What causes a tsunami

Displacement of large volumes of sea water. Most are caused by earthquakes, but they can be caused by volcanic eruptions and landslides