Restless Earth Key Terms

Restless Earth Key Terms...

Key Term
Meaning
Anticline
A fold that is convex up and has its oldest beds at its core.
Ash cloud
A large cloud of smoke and debris that forms over a volcano after it erupts.
Collision zone
When 2 continental plates collide. Neither plate is forced under the other, nor so both are forced up and form fold mountains.
Composite volcano
Composite volcanoes are made up of alternating layers of lava and ash (other volcanoes just consist of lava). They are usually found at destructive or compressional boundaries.
Cone
They are the build-up of rock from the volcanic vent; it piles up in the shape of a cone with a central crater.
Conservative plate boundary a plate boundary where the relative movement of the two crustal plates is lateral, or past each other
Constructive boundary a plate boundary where the relative movement of the crustal plates is apart from each other allowing magma to rise from the mantle and solidify to construct new crust.
Continental crust
A layer of granitic, sedimentary, and metamorphic rocks which form the continents and the areas of shallow seabed close to the shores, known as continental shelves
Continental drift
Theory that the land mass of the earth was once held as a single continent which has since split into segments which have drifted apart and into the modern configuration of the continents. Proposed by Alfred Wegener in 1912, based on observed matches in the shape of continents, their geology and biological history, it was rejected as no satisfactory mechanism could be postulated. Has regained favour, though modified, in plate tectonics theory.
Convection currents
The circular movement of a liquid or gas undergoing convection in a limited space.
Convergent plate boundary
Also known as a destructive plate boundary (because of subduction), is an actively deforming region where two (or more) tectonic plates or fragments of the lithosphere move toward one another and collide.
Crater
The depression found at the summit of a volcanic cone.
Destructive plate boundary
A plate boundary where the relative movement of the crustal plates is towards each other and where one is sub ducted beneath the other thus being destroyed as it returns to the mantle. The collision may be between oceanic plates or between an oceanic plate and a continental plate. The denser of the two will sub duct. This will never be continental crust as it is always the less dense.
Divergent plate boundary
A divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other.
Earthquake
A sudden release of energy through the earth’s crust in the form of seismic waves. Tension builds up within the crust as conventional forces in the mantle try to move the plates above but are prevented from doing so by friction between plates. When friction is overcome, an earthquake occurs.
Effects
Something which changes something else.
Epicentre
The point on the surface directly above the focus of an earthquake.
Fault
A break in the continuity of rock strata. May be due to tension, compression, and/or horizontal tearing.
Focus
In an earthquake, the actual point within the crust where the energy was released.
Fold mountains
Mountains produced by folding. Most commonly formed where a continental collides with another or with an oceanic plate.
Fumaroles
It is an opening in a planet's crust, often in the area of volcanoes, which emits steam and gases such as carbon dioxide, dioxide, hydrogen, and hydrogen.
Geosyncline
geosyncline is a term still occasionally used for a subsiding linear trough that was caused by the accumulation of sedimentary rock strata deposited in a basin and subsequently compressed, deformed, and uplifted into a mountain range, with attendant volcanism and plutonium.
Geothermal energy
Heat from within the earth. By pumping water down to hot rock layers where magma is close to the surface, we can use the resultant steam to drive turbines and produce electricity. On a smaller scale the water can be used directly to heat swimming pools and spas and the like.
Gondwanaland and Laurasia
Gondwanaland, is the name given to the more southerly of two supercontinents (the other being Laurasia) that were part of the Pangaea supercontinent that existed from approximately 510 to 180 million years ago (Mya). Gondwana formed prior to Pangaea, then became part of Pangaea, and finally broke up after the breakup of Pangaea.
Hazard
An event or condition which threatens people and property. May be natural e.g. earthquake, blizzard, or human e.g. industrial waste, HIV, or a combination e.g. drought, famine
Hot spot
A localized area of extreme heat. On earth, they refer to places where an upward plume of magma comes close to the surface in a shield area such as in Hawaii. The term may also be used to refer to areas of the surface of the sun giving off unusually large amounts of energy.
Igneous rock
A rock formed through the cooling of magma or lava. The slower the cooling, the larger the rock crystals and the harder the rock, although all igneous rocks are very hard.
Lahars
Mudflow associated with volcanic activity. Surface water mixes with volcanic ash to produce the lahar.
Lava
Molten rock flowing on the surface. Until it reaches the surface it is still called magma.
Liquefaction
Soil liquefaction refers to the process by which water-saturated, unconsolidated sediments are transformed into a substance that acts like a liquid, often in an earthquake.
Long-term impacts
An impact that will happen for a long amount of time.
Magma
Molten rock below the surface either held within the crust or in the mantle.
Magma chamber
It is a large underground pool of liquid rock found beneath the surface of the Earth.
Mantle
The layer of the earth between the crust and the core. The upper part is the lithosphere (which includes the crust above). The majority of the mantle is the asthenosphere which extends to a depth of 2900km. Mostly made of silicates, iron and magnesium.
Mid-ocean ridge
An elongated range of undersea mountains formed by the extrusion of lava, combined with the upward pressure of a convection plume, at a divergent plate margin.
Ocean trench
Deep depressions in the ocean floor (up to 11km) formed at a subduction zone where the denser plate is forced below the less dense one.
Oceanic crust
The outer layer of the Earth surface that lies beneath the oceans. As oceanic crust is denser than continental crust it generally lies below sea level.
Pangaea
The name that Wegener gave to his proposed single supercontinent in his theory of continental drift.
Plates
large pieces of rock (plates)that are floating on semifluid rock and are thus able to interact with each other at their boundaries
Primary effects
The main effect of a disaster.
Pumice
A rock that consists of highly vesicular rough textured volcanic glass, which may or may not contain crystals.
Pyroclastic flow.
The cloud of gas, ash, dust, stones and rocks emitted during a highly explosive volcanic eruption.
Rift Valley
A valley created by the subsidence of land between two parallel faults undergoing tensile forces which pull them apart.
Secondary effects
An effect that comes after the main disaster.
Secondary vent
Secondary vents are smaller outlets through which magma escapes.
Sedimentary rocks
Any rock formed from sediments under pressure from other overlying sediments.
Seismic waves
Seismic waves are waves of energy that travel through the Earth's layers, and are a result of an earthquake, explosion, or a volcano that imparts low-frequency acoustic energy.
Seismograph
An instrument that measure motions of the ground, including those of seismic waves generated by earthquakes, volcanic eruptions, and other seismic sources.
Shield volcano
A volcanic cone made up of multiple layers of basaltic lava.
Shock Waves Like an ordinary wave, it carries energy and can travel through a solid, liquid, gas.
Short-term impacts
An impact that happens for a short amount of time.
Subduction zone
His movement of an oceanic plate beneath another crustal plate. The plane of contact is known as the Benioff Zone where earthquakes occur. As the plate reaches the asthenosphere it melts.
Super volcano
Is any volcano capable of producing a volcanic eruption with anejecta volume greater than 1,000 km3. This is thousands of times larger than normal volcanic eruptions.
Syncline
A syncline is a fold with younger layers closer to the centre of the structure.
Tectonic activity
The geological processes by which rocks are deformed and that produces features of the earth's crust.
The Mercalli Scale Is a scale used for measuring the intensity of an earthquake
The Richter Scale Assigns a magnitude number to quantify the energy released by an earthquake.
Tilt meter
Is an instrument designed to measure very small changes from the vertical level, either on the ground or in structures
Tsunami
A large wave, or series of waves, caused when an earthquake causes massive undersea crust movements and/or collapses which displace the water above.
Vent
A pipe-like gap in the ground which allows volcanic material to pass through to the surface.
Volcanic bombs
Is volcanic rock being fired out of the top a volcano during an eruption
Volcanic winter
Is a reduction in global temperatures caused by ash and droplets of sulphuric acid obscuring the Sun and increasing the earth’s reflection of solar radiation after a large particularly explosive volcanic eruption.
Young fold mountains
When the two plates move towards each other again, the layers of sedimentary rock on the sea floor become crumpled and folded.

A) If a super volcano erupted, such as Yellowstone National Park, 10,000km3 of land would erupt and it would send a 25 mile high ash cloud into the atmosphere, which will quickly spread across the world. A huge amount of land around the volcano will be destroyed. Less than a week after the eruption and the ash cloud will be over Europe.
B) If an earthquake hit a richer part of the world (MEDC) there would be more effective defences and response teams compared to a poorer part of the world (LEDC). This is because the richer countries have more money to spend, therefore being more prepared. MEDC’s can afford to have more effective resources and technology for monitoring and predicting the earthquakes and then have better equipment for the response teams to use.
C) Temperature’s around the volcano rise as more activity is happening around the volcano, therefore scientists can study the volcano with a thermal imaging camera to see when the volcano is heating up or not. Also when a volcano is close to erupting it starts to release gases, the higher the sulphur content the closer the volcano is to erupting. If any of these signs happen they would set up an exclusion zone around the volcano where no one would be allowed in. any residents living in the local area in the exclusion zone would be evacuated. Good communications would be set up to warn the local people when the volcano is erupting.
D) At constructive boundaries, magma from the earth's convection currents rise to the surface through the cracks in the mantle and form volcanoes.
E) They are formed when an oceanic plate goes under another oceanic plate. Causing it to go under to the mantle. This causes it to burn making the magma turn into lava. Once the lava hardens it then forms a Composite Volcano.
F) Indian Ocean tsunami 2004
Primary effects of the tsunami were that 250,000 people died, houses and crops were destroyed. Secondary effects were things like 2 million people were made homeless because there house were destroyed, there was mass famine as there was a shortage of food and there would be a wide spread of diseases as there would be sewage and dirty water contaminating the drinking water in the town and villages.
G) Continental crust is less dense than the oceanic crust. This is because the Oceanic crust is basaltic and the continental crust is granite.
H) The epicentre is the point on the Earth's surface located directly above the focus of an earthquake. The focus is the location where the earthquake begins. The ground ruptures at this spot, then seismic waves radiate outward in all directions.
I)