Plate Movement
This term refers to the workings of the earth.
What is geophysical?
The point on the earth’s surface directly above the focus of an earthquake is known as this.
What is epicentre?
A steep cone-shaped hill that is made up of layers of ash that have been deposited during successive explosive eruptions.
What is a cinder cone volcano?
Very large sea surface waves that are caused by natural hazard events.
What are tsunamis?
The downslope movement of weathered rock materials under the influence of gravity.
What is mass movement or mass wasting?
This is the solid zone of rock on the earth, including the crust and the upper part of the mantle, that extends downwards from the earth’s surface to a depth of about 70 kilometres.
What is litosphere?
Also known as compressional waves or longitudinal waves, these travel at speeds between 2 and 8 kilometres per second through the earth’s crust.
What are P waves?
These form when a eruption spews out combinations of ash, lava, pumice or tephra at various times, which are deposited in layers to form a cone.
What are composite cone volcanoes, also known as stratovolcanoes,
Tsunamis usually travel at speeds averaging .......... in the open ocean.
What are 700 (and up to 1,000) kilometres per hour?
What are the four factors that promote mass movement?
What are slope, water, texture of the weathered material and triggering event (initial impetus)?
The heavier, denser layer of the crust is known as this. The world’s ocean beds are made up of this.
What is sima (silica and magnesia)?
Unlike P waves, S waves cannot travel through these.
What are liquids?
This is a liquid mudflow or debris flow made up of a slurry of pyroclastic materials, rocks and water.
What is a lahar?
What four natural hazard events may cause tsunamis?
What are underwater earthquakes, landslides, volcanic activity and a meteorite strike?
Each form of mass movement involves one or more of four types that depend on the four processes: ......?
What are creep, flow, slides and falls, and subsidence?
Convection currents occur in the mantle as a result of this.
What is radioactive decay?
These move backwards and forwards across the surface at right angles to the P waves.
What are love waves?
Definition: having a thick or sticky consistency: having or characterised by a high resistance to flow.
What is viscous?
One of the most severe tsunamis in recent times occurred when?
What is 26th December 2004?
These form when saturated soil particles on steep slopes expand during rain, and then contract when the soil dries again.
What are terracettes?
Where a convection current rises in the mantle as a plume, volcanic activity occurs as the plates above are pushed upwards and outwards, thus drifting apart as new crust is formed. This creates a number of these.
What are spreading ridges?
Mention three secondary hazards that earthquakes may trigger.
What are landslides, liquefaction and tsunamis?
On Hawaii, two different types of lava form during eruptions, and they in turn form very different surfaces when they solidify. The first type of lava cools quickly to form this, which has a very sharp, rough surface.
What is an a'a (as opposed to pahoehoe)?
In addition to the people killed in the Indian Ocean Tsunami, it was estimated that about .......... people were displaced from their homes by the tsunami.
What are 1.5 million people?
Typically talus (= scree) slopes come to rest at an angle of .....°, which is sometimes known as the critical angle.
What are 35°?