Geography - Natural Hazards
Tectonic Hazards
Earth Structure
Outer Core - Iron and Nickel. 4,400 degrees. Liquid (less pressure) / Semi-liquid
Mantle - 1,000 to 3,700 degrees. Solid / Semi-solid
Inner Core - Iron and Nickel. 6,000 degrees. Pressure makes it solid
Types of movement
Convection currents - Plate is dragged down ny convection currents, this is where the mantle is heated and rises, then cools and falls again
Ridge push - Plate is pushed by the weight of a mid-ocean ridge
Slab pull - Plate is pulled down by its cold, dense subducting section
Margin types
Destructive - Two plates push together. Land is destroyed. Denser plate sinks below the less dense plate. VOlcanoes and earthquakes can occur due to friction and the subducting plate melting into magma
Constructive - Plates move apart from eachother. Land is created. Magma rises through fissures, volcanoes occur
Conservative - Plates slide past eachother, rough edges get caught due to friction, pressure builds up until it is released causing earthquakes
Crust
Oceanic Crust - Found in sea, Heavy, Young, Dense, Made of Basalt
Continental Crust - Found on land, Light, Old, Less dense, Made of Granite
Tectonic case studies
Japan, March 2011
Haiti, 2010
- Positioned 19th in terms of HDI
- GDP per capita of $39,000
Causes - It occured between the Eurasian and Pacific plates at a subduction zone, however there is some disagreement on whether it was on the Eurasian plate or a microplate off of the North American plate. This led to a magnitude 9 earthquake
Primary effects - Around 16,000 people died and 6,000 were injured
300,000 buildings were completely destroyed and a further 1 million were damaged
Secondary effects - 4.4 million people in north eastern Japan were left without electricity
The earthquake resulted in a 40.5 metre tsunami
Immediate responses - 91 countries offered aid, from blankets and food to search dogs and military transport
A tsunami warning was issued 3 minutes after the earthquake
Long-term responses - Earthquake engineers examined the damage, looking for ways to construct buildings more resistent to earthquakes and tsunamis
Just 6 days after the earthquake a major motorway was repaired - this shows that Japanese are well equipped to cope with these disasters
Causes - The North-American plate was sliding past the Carribean plate at a conservative plate boundary, presure built and realeased causing a magnitue 7 earthquake
- Haiti is 169th in terms of HDI
- Haiti's GDP per capita is around $750
Primary effects - 250,000 people were killed and a further 1 million people were made homeless
250,000 homes were either destroyed or badly damages
Secondary effects - 1 in 5 people lost their jobs because so many buildings were destroyed
The large numbers of bodies meant that diseases such as Cholera became a big problem
Immediate responses - $100 million in aid was given by the USA and $330 was given by the EU
810,000 people were placed in aid camps
Healthcare supplies were provided to reduce the spread of disease
Long-term responses - 98% of the rubble on roads hadn't been cleared
SUpport was provided for people without jobs through programs such as cash/food for work
Water and sanitation was eventually provided for 1.7 million people
Why do people live in Tectonically active areas
Geothermal energy
Fertile soil
Inertia (People don't want to move)
Tourism industry
Stores of minerals and metals
Friends and family
Managing Tectonic hazards
Monotoring - Using equipment to detect the warning signs of events
Earthquakes - Detecting foreshocks using seismometers and Radon using Radon detection devices
Volcanoes - Detecting changes in shape of ground using tiltimetres and ground and river temperatrues
Prediction - Using historical evidence to make an estimate on when and where tectonic hazards can occur
Earthquakes - Extremely difficult to predict
Volcanoes - They usually give advance warning signals
Protection - Designing buildings to withstand tectonic hazards
Earthquakes - Sea walls and Base relations
Volcanoes - Evacuations instructed by local authorities, as buildings can't be designed to withstand an eruption
Planning - Identifying and avoiding places most at risk
Earthquake - Practice drills, Preparing supplies and evacuation centres, Securing objects/furniture
Volcanoes - Evacuation, Exclusion zones and First aid training
Extreme Weather Hazards
Pressure Belts
Global circulation is created by the fact warm air rises and cool air sinks
Cool air sinking = High pressure
Warm air rising = Low pressure
This movement between pressure systems creates three main cells
Polar Cell
Ferrel Cell
Hadley Cell
Hadley Cell
Ferrel Cell
Polar Cell
Tropical Storms
1) Air on the surface of the ocean is heated to 27 degrees, which encouarges evaporation and the rising of air and water vapour
2) Hot, humid air rises, cools and condenses. This helps to form huge cumulonimbus clouds
3) Rising air creates low pressure. Air rushes to fill the gap left by rising air
4)The rotation of Earth means winds to not blow straight (Coriolis effect). So winds circle towards the centre and thes torm continues to feed itself
5) The whole system moves westward towards land (in the Northern hemisphere)
6) When the system croses land it looses its source of heat and moisture
7) The tropical storm loses its energy and dies out
Temps of 27 degrees
Winds of 74 mph
And a water depth of at least 60m
Is needed for a Tropcial storm to form
Typhoon Haiyan
The Phillipines is an NEE being one of the World's biggest emerging markets, but some parts are still very poor
Primary effects - 6,300 people were killed, and most were drowned in the 7m storm surge
90% of Tacloban was destroyed
Overall damages totalled to $12 billion
Secondary effects - Fishing waters were contaminated as an oil tanker ran aground leading to an 800,000 litre oil spill
Seawater, along with chemicals from industry and sewerage systems contaminated surface and groundwater
Immediate responses - Over 1,200 evacuation centres were set up for the Homeless
800,000 people were evacuated following a televised announcement from the president
Within 2 weeks 1 million food packs and 250,00 litres of water were distributed
Long-term responses - Cash for work programmes were created - People were paid to help clear debris and build the city
They set up a no-build zone along the Eastern Visayas to avoid future damage from storm surges
Mangroves were replanted to absorb future storm surges
Reducing the effects of Tropical Storms
Monitoring - Satellites monitor cloud pathways
NASA monitor the Atlantic using two drones
Satellites monitor high-altitude clouds every 3 hours which indicate whether a tropical storm will intensify
Protection - Reinforce buildings
Develop costal flood defences
Create no-build zones along low-lying areas
Prediction - Supercomputers give five days warning and predict a location within 400km
Early warnings are issued by national hurricaine centres around the world