Theme 2: Plate Tectonics
Plate tectonics definitions
Terms in this set (76)
A section of the lithosphere that slowly moves over the asthenosphere, carrying pieces of continental and oceanic crust.
A break in the Earth's crust where masses of rock slip past each other.
Cinder cone volcano
A steep, cone-shaped hill or small mountain made of volcanic ash, cinders, and bombs piled up around a volcano's opening.
A wide, gently sloping mountain made of layers of lava and formed by quiet eruptions.
The theory that pieces of the Earth's lithosphere are in constant motion, driven by convection currents in the mantle.
The hypothesis that the continents slowly move across Earth's surface.
An undersea mountain chain where new ocean floor is produced; produced by a divergent plate boundary.
The process by which molten material adds new oceanic crust to the ocean floor.
A deep valley along the ocean floor beneath which oceanic crust slowly sinks toward the mantle.
A deep valley that forms where two plates move apart.
The process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary.
The thicker layer of crust of the continents composed largely of granite making it less dense than oceanic crust.
A dark, dense, igneous rock with a fine texture, found in oceanic crust.
A usually light-colored igneous rock that is found in continental crust.
The center of the Earth made mostly of the metals iron and nickel.
The transfer of heat by movement of currents in a fluid.
Plate boundary/plate margin
The boundary between two plates, which may be moving towards, away or sideways past each other.
A dense, destructive mass of very hot ash, lava fragments, and gases ejected explosively from a volcano and typically flowing at great speed.
A layer of molten iron and nickel that surrounds the inner core of Earth. Average depth of 2300km.
A bowl-shaped area that forms around a volcano's central opening.
place at which majority of the magma comes out of the magma chamber
The area covered by lava as it pours out of a volcano's vent
Circular currents in the mantle caused by the magma being heated by the core of the Earth.
The point beneath Earth's surface where rock breaks under stress and causes an earthquake
the scale used to measure the strength or magnitude of an earthquake
an instrument that detects and records the earth's movements. It measures the strength of an earthquake.
A giant wave usually caused by an earthquake beneath the ocean floor.
vibrations that travel through Earth carrying the energy released during an earthquake
The outer layer of the earth. It is made from solid rock and is between 0-60 km thick.
Is the thickest section of the Earth, approximately 2,900 km. It is made up of semi-molten rock called magma.
Found at the centre of the Earth, it is solid and made from iron and nickel. The temperatures goes up to 5,500°C.
Is a hypothetical supercontinent that existed when all continents were joined together 300 to 200 million years ago.
The part of the earth's crusts that contains the landmasses. It is approximately 10-60 km thick. It covers about 40% of the earth's surface and is less dense than Oceanic crust.
The part of the earth's crust that contains the oceans. It is approximately 5-7 km thick and covers about 60% of the earths surface. It is more dense than Continental crust.
Plate Boundary (margin)
The edge of the tectonic plates. The location where two plates meet and where tectonic events such as earthquakes and volcanoes occur.
Destructive Plate Boundary
A convergent plate boundary where an oceanic and a continental crust collide. They form features such as volcanoes, fold mountains and ocean trenches.
Constructive Plate Boundary
A divergent plate boundary where two plates move apart. Usually the plates are oceanic and they form features such as ridges. An example of which is the Mid Atlantic Ridge.
Collision Plate Boundary
A convergent plate boundary where two continental crusts collide. There is alway a lot of uplift forming fold mountains. Example: Himalayas
No Volcanoes form at this plate boundary!
Conservative Plate Boundary
A transform plate boundary where two plates move next to each other (side by side).
Example: San Andreas Fault
No volcanoes form at this plate boundary!
An underwater landform formed at a Destructive plate boundary. Where the oceanic plate becomes subducted under the continental it creates an extremely deep section of ocean.
Example: Mariana trench near the Philippenes
An underwater landform created at a constructive plate boundary. When the two oceanic plates move apart lava erupts onto either side of the plate forming large underwater mountains (ridges) that can sometimes grow into islands.
A landform that is created at both destructive and collisional plate boundaries. The tectonic forces push the crust upwards forming huge mountain ranges.
Example: Andes, Himalayas, Rocky Mountains
The section of the oceanic plate that is pushed (subducted) under the continental plate in a destructive plate boundary. It is placed under extreme pressure, heat and friction melting it and causing volcanoes directly above its location.
A tectonic hazard generated by the movement of tectonic plates releasing shock waves (shacking the ground). They occur on ALL plate boundaries
A tectonic hazard caused by lava erupting onto the earth's surface. There are many different types of volcano depending on the characteristics of the lava. They do NOT occur on all plate boundaries.
The circulation of magma deep in the mantle caused by different levels of heat. This is the driving force behind plate tectonics and causes the plate movements.
Molten rock found beneath the earth's surface.
Molten rock rock (magma) after it has erupted onto the earth's surface.
A landform formed when a constructive plate boundary occurs between plates made from continental crust.
The exact point deep in the earths crust where the tectonic pressure is released. This is where the earthquake occurs and the shock waves emanate (come) from.
The point on the surface of the earth directly above the focus.
A large cavity found in the earths crust that is directly beneath a volcano. It fills with magma and when it reaches capacity there is usually a volcanic eruption.
A type of volcano usually created by non viscous lava near constructive plate boundaries. It is relatively low in profile and quite spread out.
A type of volcano created by viscous lava containing many impurities near destructive plate boundaries. The impurities (such as water) help create an explosive element to these volcanoes. The cone is made up from a combination of lava, ash and pyroclastic material.
A volcanic mud flow that occurs because the volcano's crater is either covered with ice and snow or has a lake inside of it. The mud flow can be very dangerous.
Example: Nevado del Ruiz, 1985
The tubular passage from which lava can reach the earth's surface during an eruption.
An explosion of lava, ash and other pyroclastic materials from a volcano.
Sticky, it does not flow easily.
The most commonly used scale or measurement of the magnitude of an earthquake. It is a 10 point scale where each point is 10x larger in magnitude than the last.
A hazard that occurs as a direct impact of the event. For example during an earthquake it could be the shaking of the ground potentially causing building collapse.
A hazard that can occur after the event usually due to damage caused. For example the spread of disease due to decaying bodies in the aftermath of a large earthquake.
Size or scale of a hazard.
Ring of Fire
An area surrounding the Pacific ocean. It is called the ring of fire due to the high concentration of volcanoes found there because of the destructive plate boundaries.
Lava or Volcanic Bomb
A large piece of volcanic material or semi molten rock that is ejected into the air due to a large explosive volcanic eruption.
The large column of ash and particles that is thrown up into the atmosphere due to a volcanic eruption. This can stop flights from flying and also when it falls down on the earths surface it can damage vegetation and in some instances the weight of the ash can collapse buildings.
To move apart. In this unit it refers to plates that are moving apart.
To move together. In this unit it refers to plates that are moving towards each other.
The extent that a people or community are ready to deal with the events of a hazard.
Electrical energy generated by using magma to turn water into steam and then using that steam to drive turbines creating electricity.
Earthquakes that are smaller in magnitude (but can still be very destructive) that happen after the main event.
Large sections of the earth's crust that 'float' on the mantle and interact with each other potentially causing earthquakes and volcanoes.
A volcano that has not erupted in the last 100 years but still has the potential to erupt.
A 'dead' volcano that has not erupted in the last 10,000 years and is highly unlikely to ever erupt again.
The study of earthquakes
An area found on a destructive plate boundary. The place where the oceanic plate 'rubs' on the continental plate. This area of friction is where most earthquakes occur.
A volcano that is erupting or has erupted in the last 100 years. It may erupt again in the near future.