What is a SUPERVOLCANO?
It's a volcano that erupts at least 1000 km^3 of material.
What is a NATURAL HAZARD?
A naturally occurring event that will have a negative impact on people.
What is RISK?
It's the probability of a natural hazard occurring and the losses or damage that might result from that natural hazard.
What is a NATURAL DISASTER?
It's when a natural hazard causes damage and the people affected are unable to cope.
What is a VULNERABILITY?
It's the characteristics and circumstances of people in a community that make them susceptible to the impacts of a natural hazard.
What are PLATE TECTONICS?
A theory developed in the 1960s that helps explain the formation of some of the important features on the Earth's surface and how the continents move.
What are FOLD MOUNTAINS?
They are mountains created when two or more tectonic plates are pushed together, compressing the rocks and folding them upwards.
What is the ASTHENOSPHERE?
It's the layer of the Earth below the lithosphere, it is hotter and weaker than the lithosphere above and is capable of plastic flow (deformation of material that remains rigid)
What is the SIMA?
The other name for the oceanic crust, which is rich in silicate and magnesium minerals.
What is the SIAL?
The other name for the continental crust, which is rich in silicate and aluminium minerals.
What is BASALT?
A fine grained extrusive igneous rock formed by the cooling of lava at constructive plate margins.
What is GRANITE?
It's a coarse grained intrusive igneous rock comprising the minerals quartz, feldspar and mica, it is formed at destructive plate margins.
What is a TECTONIC PLATE?
It's a piece of lithosphere that moves slowly on the asthenosphere, seven major, eight minor and numerous micro plates have been identified.
What is the LITHOSPHERE?
It's the outer and rigid layer of the Earth, comprising the crust and the upper mantle.
What are CONVECTION CURRENTS?
They transfer heat from place to place, denser colder fluid sinks into warmer areas, heat from the Earth's core causes convection currents in the mantle.
What is a PLATE BOUNDARY?
It's where two or more plates meet; the three main types of plate boundary are constructive, destructive and conservative.
What is SEA FLOOR SPREADING?
It's the process by which oceans are formed at constructive plate boundaries, new oceanic crust is formed as two oceanic plates move apart.
What is RIDGE PUSH?
It's a gravitational force that causes an oceanic plate to move away from the crest of a mid ocean ridge and into a subduction zone; it works together with slab pull.
What is a SHIELD VOLCANO?
It's a broad volcano built up from the repeated eruption of basalt.
What is a BASIC VOLCANO?
It's a broad volcano built up from the repeated eruption of basalt.
What is a RIFT VALLEY?
It's an area where a continent is being stretched and the central block moves downwards.
What is a SLAB PULL?
It's the force at a destructive plate boundary, where the oceanic plate sinks beneath the adjacent plate, as a result of its own weight, the descending plate is pulled by gravity through the asthenosphere.
What is a SUBDUCTION ZONE?
It's a zone where the oceanic plate is deflected (subducted) down into the mantle, at the surface the subduction zone coincides with ocean trenches.
What is an OCEAN TRENCH?
It's a depression of the ocean floor that runs parallel to a destructive plate boundary.
What is a BENIOFF ZONE?
It's a zone of the earthquake foci in the upper part of a subducting oceanic plate at a destructive plate boundary.
What is a COMPOSITE VOLCANO?
It's a volcano built up by alternating layers of lava and ash, conical in shape. Also known as a strato volcano.
What is an ACIDIC VOLCANO?
It's a volcano that is made up of just lava, it is steeped sided as the lava does not flow easily, and it builds up into a convex cone shape.
What is an ISLAND ARC?
It's a chain of volcanoes, generally with an arc shape, that run parallel to an oceanic trench at a destructive (oceanic oceanic) plate boundary.
What is a COLLISION ZONE?
It's a destructive plate boundary between two continental plates, resulting in fold mountains.
What is the FOCUS?
It is the location under the Earth's surface where an earthquake originates.
What is the EPICENTRE?
It's the point on the Earth's surface directly above the focus of an earthquake.
What is the RICHTER SCALE?
It's a measure of the magnitude of an earthquake, taken with a seismograph and with a scale of one to ten ten being the most powerful, it is a logarithmic scale which means that if an earthquake measures two on the scale it is ten times more powerful than an earthquake that measures one.
What is LIQUEFACTION?
The process where loose sediments with a high water content behave like a liquid when shaken by an earthquake.
What is a TSUNAMI?
It's a large wave created by ocean floor displacement or landslides.
What is PYROCLASTIC MATERIAL?
Very hot gases, ash and volcanic bombs, pyroclastic flows can reach speeds of over 100 km h^-1 at temperatures of 200 to 700 C
What are LAHARS?
Mudflows of volcanic material, caused when ash mixes with heavy rain or water from melting snow.
What is the INTER TROPICAL CONVERGENCE ZONE?
The ITCZ is a low pressure belt that lies around the equator, where the northeast and southeast trade winds meet. It receives high precipitation because of intense heating from the Sun.
What is the EL NINO SOUTHERN OSCILLATION?
The ENSO is the change in the prevailing winds that leads to a change in the pattern of currents in the oceans of the south Pacific.
What is DISCHARGE?
It's the volume of water passing a measuring point of gauging station in a given time, measured in cubic metres per second (cumecs)
What is LAG TIME?
The time difference between peak rainfall and peak discharge.
What is INFILTRATION CAPACITY?
The maximum rate that water enters soil.
What is ANTECEDENT SOIL MOISTURE?
The amount of moisture present in the soil before a rainfall event.
What does IMPERMEABLE mean?
It means something that does not allow water to pass through.
What is PERCOLATION?
The vertical movement of water from the soil into the underlying rock.
What is INTERCEPTION?
The process by which vegetation prevents rainfall from reaching the surface directly, the intercepted rainfall is temporarily held as interception storage and then either falls directly to the ground or is evaporated back to the atmosphere.