earthquakes and volcanoes
earthquakes
volcanoes
plates
causes & effects
opportunities of volcanoes
I can describe and explain the hazards and opportunities which volcanoes present to people.
what is done
types of volcanoe
shield
composite
they are low, with gently sloping sides
they are formed by eruptions of thin, runny lava
shield volcanoes are usually found at constructive boundaries
eruptions tend to be frequent but relatively gentle.
Composite volcanoes are made up of alternating layers of lava and ash (other volcanoes just consist of lava).
The eruptions from these volcanoes may be a pyroclastic flow rather than a lava flow. A pyroclastic flow is a mixture of hot steam, ash, rock and dust.
they are usually found at destructive boundaries
A pyroclastic flow can roll down the sides of a volcano at very high speeds and with temperatures of over 400°C.
features of a volcanoe
The main vent is the main outlet for the magma to escape.
Secondary vents are smaller outlets through which magma escapes.
The magma chamber is a collection of magma inside the Earth, below the volcano.
The crater is created after an eruption blows the top off the volcano.
types of plates
continental
oceanic
usually quite thick (between 35 to 100 km)
thinner (between 5 and 10 km).
carries land
carries water
younger than continental
the Earth's crust is broken up into pieces called plates
structure of the earth
The inner core is in the centre and is the hottest part of the Earth. It is solid and made up of iron and nickel with temperatures of up to 5,500°C. With its immense heat energy, the inner core is like the engine room of the Earth
The outer core is the layer surrounding the inner core. It is a liquid layer, also made up of iron and nickel. It is still extremely hot, with temperatures similar to the inner core
The mantle is the widest section of the Earth. It has a diameter of approximately 2,900 km. The mantle 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
The crust is the outer layer of the earth. It is a thin layer between 5-70 km thick. The crust is the solid rock layer upon which we live
types of plate boundaries
constructive
conservative
destructive
formed when two plates slide past each other in opposite directions or different speeds
formed when two plates move apart.
formed when two plates collide.
subduction zones and ocean trenches will be formed.
ususally involves continetal and oceanic plate
the oceanic plate is denser than the continental plate so, the oceanic plate is forced underneath the continental plate
this is called the subduction zone
as the plate is forced down, there will be deep gap under the sea which is known as an ocean trench
when the oceanic plate is forced below the continental plate earthquakes are triggered
an example of this plate movement is along the coastline of South America (at the Nazca and South American plate boundary).
as the plates move apart (very slowly), magma rises from the mantle, the magma erupts to the surface of the earth
mid-ocean ridges will be formed
fault lines will be formed
build up in friction that is released as an earthquake
the convection currents move the plates.
epicentre- the point on the Earth's surface above the focus
focus- the point inside the crust where the pressure is released
seismic waves are released from the focus
long term
short term
death and injurt
homes destroyed
looting
transport links destroyed
water pipes burst/ contaminated water
fires may start
landslides
tsunamis
re-housing & refugee camps
spread of disease
cost of rebuilding
important landmarks lost
identify risks
build safer, sturdier structure
educate about earthquake safety
plan evactution areas
remove those most at risk
monitor volcanoes
soil is very fertile
jobs in hotels, restaurants, tour guids and gift shops
case study- Haiti
case study- Montserrat
what happened
soufriere hills volcanoe on the south of the island began erupting on 18th July 1995
erupted again in 1997 (most violent)
between 1995-1997 there was pyroclastic flows
PSI
population of 12,000
people evacuated to the north
19 people killed
capital Plymouth
impact
short
long
only hospital, airport & homes destroyed
23 deaths & >100 injured
plyouth covered in ash
main airpiort closed
75% of island covered in ash
rebuild homes & infrastructure
environmental damage
population from 12,000 in 1995 to 1500 in 2001
destructive plate boundary
economy based on faring, fishing & tourism
responses
5000 evactuated
royal navy sent ships to help evacuate
UK sent £41mil in relief aid & £ 75mil for development
evacuation camps
monitoring stations
what happened
PSI
impacts
responses
12th january 2010 middle of afternoon
7 on richter scale
shallow epicentre (65km)
small tsunami
52 aftershocks
short term
long term
220,000 dieed
1.5mil homeless
300,000 building destroyed
main prison, port-au-prince cathedral and supreme court destroyed
1/3 of all buildings destroyed
$8bil cost to economy
unemployment
80% living in poverty
govt authority collapsed
short term
long term
american coastguard helped
European search and rescue team
US aircraft delivered water
hygiene packs for refugees
23 charities offered >$1.1bil
Senegal welcomed migration
locals educated
capital Port-au-Prince
population of 9.8mil
in the caribbean sea
North American & Caribbean plates