Natural Hazzard Flashcards
What is a natural hazard?
A natural event that threatens people or has potential to cause damage, destruction and death
What are the different types of hazzard?
•Atmospheric
•Geological
•Water Based
•Biological
What is an atmospheric hazzard?
Created in the atmosphere by the weather/by the movement of air an water e.g. wind,tornadoes,snow
What is a geological hazzard?
Created by the movement of the Earth’s tectonic plates or surface rock and soils e.g. earthquakes, landslides
What is a water based hazard?
Created by rivers,sea or oceans e g. floods
What are biological hazzards?
Any biological substance that poses a threat to the health of people e.g. wildfires
What are some human factors affecting hazard risk?
•Planning Laws-Teaching the population how to prepare and respond to an earthquake can reduce the hazard risk.
•Frequency-The more often a population is affected by a hazard, the more likely they are to adapt their way of life to cope
•Strength of infrastructure- infrastructure in HICs may be built with cross bracing to avoid collapsing
What are some physical factors that are affecting hazard risk?
*Magnitude-This is the size of the hazard event. The greater the force of the hazard the more likely it is the hazard will have a greater impact on people
*The Rock Type-An earthquake in an area of soft rock is larger and lasts longer than one in an area of hard rock. Soft rock also makes the risk of liquefaction greater whixh can damage buildings
Coastline Shape-For example, a gently sloping coastline will often suffer more damage than a steep coastline in a hurricane’s storm surge
What is the crust?
The outermost layer of the Earth
What is the mantle?
A layer of rock between the core and the crust made of soft molten rock (3800°C)
What is the outer core?
It is dense hot rock at the centre of the earth made of liquid iron and nickel (5500°C)
What is the inner core?
It is dense hot rock at the centre of the earth (5500°C)
Why do tectonic plates move?
Convection currents in the mantle
What are convection currents?
the motion of molten rock in the mantle as heat rises in the earth’s core heating up magma and causing it to rise
What are the different types of crust?
Oceanic and continental
What are the features of oceanic crust?
•found under sea
•is thin(5-10km)
•very dense
What are the features of continental crust?
•found under land
•is thicker than oceanic crust (20-200km)
•less dense
What are earthquakes?
Vibrations in the earth’s crust that create a sudden shaking in the surface
What are volcanoes?
A landforms created by magma being forced into the earth’s crust and erupting onto the earth’s surface through a vent
What are 2 different types of volcanoes?
Composite and Sheild
What is a composite volcano?
•found at destructive plate margins
• steep sided, layers of ash and lava, magma is very sticky and cools quickly
•very explosive
What is a shield volcano?
•found at constructive plate margins
•dome shaped with sloping sides
•magma is runny and flows long distances before it cools
•more gentle explosions
What happens at a destructive plate margin?
•Where an oceanic plate meets a
continental plate. They are moving
towards each other.
•The denser oceanic plate is subducted beneath the less dense continental plate.
•As it sinks, it melts and makes magma called andesite.
•The sinking oceanic plate can stick to the continental plate, pressure builds up against friction causing earthquakes
•volcanoes are formed when the pressure of the magma builds up beneath the Earth’s surface. The magma escapes through weaknesses in the rock and rises up through a composite volcano
What happens at a constructive plate margin?
• Where two oceanic plates are moving apart from each other.
•New oceanic crust is forming constantly in the gap created.
•The magma is injected between the two plates. As it cools it forms new oceanic crust.
•The magma is runny. Shallow sided
volcanoes form
•Earthquakes are caused by friction as the plates tear apart.
What happens at a conservative plate margin?
• As plates slide past each other,
friction between them causes
earthquakes.
•Plates can be moving in different
directions or the same direction.
•No volcanoes are formed.
