Unit 1A - Tectonic Hazards

A natural hazard is defined as a natural process which could cause death, injury or disruption to humans, or destroy property and possessions.

Extreme events that do not pose a threat to humans are STILL counted as hazards.

What are the two main types of natural hazard?

Which option is an example of a geological hazard?

Which option is an example of a meteorological hazard?

Hazard risk is defined as the probability that a natural hazard occurs. What different factors can affect hazard risk? (hint: there are 3 answers)

Label the earth's surface.

The [blank_start]core[blank_end] of the Earth is a ball of [blank_start]solid[blank_end] (inner) and [blank_start]liquid[blank_end] (outer) iron and nickel. Around the core is the [blank_start]mantle[blank_end], which is semi-molten rock that moves very [blank_start]slowly[blank_end]. The outer layer of the Earth is the [blank_start]crust[blank_end]. The [blank_start]crust[blank_end] is divided into slabs called [blank_start]tectonic[blank_end] plates (that float on the mantle). Plates are made up of two type of crust: [blank_start]continental[blank_end] and [blank_start]oceanic[blank_end]. The places where plates meet are called plate [blank_start]margins[blank_end] or plate [blank_start]boundaries[blank_end].

What are the three different types of plate margin?

[blank_start]Destructive[blank_end] margins occur where two plates are moving towards each other. When a [blank_start]continental[blank_end] plate meets an oceanic plate, the oceanic plate is forced down into the [blank_start]mantle[blank_end] and destroyed. When two [blank_start]continental[blank_end] plates meet the plates collide, fold and are forced [blank_start]upwards.[blank_end] [blank_start]Constructive[blank_end] margins occur when plates are moving away from each other. This causes [blank_start]magma[blank_end] to rise and cool, filling in the gap and creating new [blank_start]crust[blank_end]. [blank_start]Conservative[blank_end] margins occur when plates move [blank_start]sideways[blank_end] past each other, or move in the same direction but at different [blank_start]speeds[blank_end]. Crust is not [blank_start]destroyed or created[blank_end].

Volcanoes are found at destructive and constructive plate margins.

At a destructive margin the [blank_start]oceanic[blank_end] plate is forced downwards into the mantle, where it is melted and destroyed. This forms a pool of [blank_start]magma[blank_end], which then rises through cracks in the crust known as [blank_start]vents[blank_end]. The magma then erupts onto the surface of the earth (where it is now described as [blank_start]lava[blank_end]) and forms a [blank_start]volcano[blank_end]. At a constructive margin the magma rises up into the gap caused by plates [blank_start]moving apart[blank_end], creating a volcano. Volcanoes can also form over parts of the [blank_start]mantle[blank_end] that are extremely hot. These areas are known as [blank_start]hotspots[blank_end].

At which type(s) of plate margin do earthquakes occur?

Earthquakes are caused when plates get stuck and have to jerk past each other. As they move past each other vibrations (also known as shock waves) are sent out, which form the earthquake.

The focus of the earthquake is on the Earth's surface.

Which three types of scales are used to measure earthquakes?

When a volcano erupts, what can it emit?

What is a pyroclastic flow?