Natural Hazards Flashcards
What is a natural hazard
A natural hazard is a natural event that threatens people or has the potential to cause damage, destruction and death
Name the 4 types of natural hazards
Types of natural hazards
Tectonic (anything to do with the earth)
Atmospheric (climatic, tropical storms, weather)
Biological (anything to do with biomass, forest fires)
Geomorphological (Rock type, landslides)
Give examples of tectonic hazards
Earthquake
Avalanches
Tsunami
Landslide (due to tectonic activity)
Volcanic eruptions and ash fall
Give examples of atmospheric hazards
Tropical Storm
Drought
Tornado
Give example of geomorphological hazards
Landslides
Flooding
Mudflows
Give example of a biological hazards
Forest fires
Define hazard risk
A hazard risk is the probability or chance that a natural hazard may take place
Give an example of a hazard risk
An example of a hazard risk is living at the boundary of two tectonic plates.
This increased the hazard risk
Define tectonic hazard
A tectonic hazard is a natural hazard caused by movement of tectonic plates
What is a tectonic plate
A tectonic plate is a rigid segment of the Earth’s crust which can ‘float’ across the heavier, semi-molten rock below. Continental plates are less dense but thicker than oceanic plates
What is the earth made up of
The earth is made up of:
Crust (top layer)
Mantle
Outer core
Inner core
What is the crust
The crust is the thin, solid outer layer of the earth between 0-60km thick. It is divided up into plates which move on the mantle.
What is the mantle
The mantle is the widest section of the Earth at 2,900 km and is made up of semi-molten rock called magma. In the upper parts of the mantle, the rock is hard, but lower down the rock is soft and beginning to melt.
What is the outer core
The outer core is the layer surrounding the inner core. It is a liquid layer, also made up of iron and nickel. It is extremely hot, similar to the inner core.
What is the inner core
The inner core is in the central part of the earth. It is solid iron and nickel with temperatures of up to 5500 degrees Celsius (around same temperature as the sun)
What is the lithosphere
The crust and the upper mantle together form the lithosphere
What is the asthenosphere
The very upper part of the mantle is called the asthenosphere
Complete the sentence
The lithosphere is broken into several __________called _______, which move slowly over the mantle
The lithosphere is broken into several fragments called tectonic plates which move slowly over the mantle
What is a plate margin
The region where two or more tectonic plates meet. It is a zone of intense seismic activity.
State the two types of crust
Two types of crust:
Oceanic and Continental
What is continental crust
Continental crust is the surface of the Earth’s crust found underneath large land masses
What is oceanic crust
Oceanic crust is the surface of the Earth’s crust found underneath the oceans, forming the ocean floor
State the characteristics of continental crust
Thick: 20-200km
It is less dense than oceanic crust
Composed mainly of granite rock
It does not get destroyed
Old: Up to 3.8 billion years old
Found under land masses or continents
State the characteristics of Oceanic Crust
Thin: 5-10km
It is denser than continental crust
Formed of Basaltic rock
Sinks/subducts when it meets continental plate
Young: Usually less than 200 million years old
This is because they are destroyed at destructive plate boundaries, while continental crust are not
Oceanic crust is found underneath oceans
