Transcript File

Vulcanicity
• Intrusive
• Extrusive – Types of Volcano
• Volcanoes
• Case Studies
• Volcanoes in the UK
Intrusive
Intrusive landforms
• Batholiths are large bodies of intrusive igneous rock . Formed
when magma cools and crystallizes beneath Earth's surface
• A laccolith is a intrusion that has been injected between two
layers of sedimentary rock.
• Sills: form when magma intrudes between the rock layers,
forming a horizontal or gently-dipping sheet of igneous rock.
• A Dyke: is a vertical intrusion a rock which carries the igneous
rock upwards
Extrusive Volcanic Activity
Types of Volcano
Vulcanicity- Types of Volcano
Vulcanicity- Types of Volcano
Vulcanicity- Types of Volcano
Minor forms of extrusive activity include geysers, hot springs, fumaroles, sulfatara, boiling
mud and mud volcanoes. This minor activity occurs in places that are geothermal and there are
normally multiple examples of different activity in the same place. Geysers for example
commonly occur in clusters called geyser fields.
Other forms of extrusive volcanic
activity
There is currently little volcanic activity in
the UK, the only form of activity is that of hot
springs in bath.
However there is evidence that in the past
there has been extensive volcanic activity
both extrusive and intrusive.
When lava is forced to the surface only
a limited amount of the mass actually
protrudes through the surface. The rest
of the mass is intruded into the crust
where it solidifies into a range of
features. These features can be exposed
by erosion.
Volcanic activity in the UK
Batholiths are formed when masses of magma cool
and solidify. As the magma cools large crystals are
formed in the rock like granite. Batholiths are often
dome shaped and exposed by erosion. This is the
case in areas such as Dartmoor and The Isle of Arran
in Scotland. The areas surrounding the batholith are
affected by the heat and pressure form the intrusion
of the magma. This forms metamorphic aureole
where rocks like limestone for example are
transformed, limestone becomes marble. Batholiths
are unaffected by existing rocks. Sometimes a
smaller injection of magma can form a lens shape
that is intruded between the layers of rock this forces
the layers of rock upwards. This feature is known as a
laccolith, it can also be exposed by erosion, an
example of this from the UK would be the Eildon hills
on the Scottish borders.
Volcanic activity in the UK
A dyke is a vertical intrusion with horizontal cooling cracks. A dyke will cut across the bedding
planes of the rocks into which they have intruded. Dykes often occur in groups, known as dyke
swarms. Many Scottish islands such as the Isle of Mull have swarms of dykes associated with one
intrusive event.
Sills are the horizontal intrusions alone the lines of the bedding planes. Sills have vertical cooling
cracks. Examples of sills include the Great Whin sill which is home to Hadrian’s Wall and
Drumadoon on the isle of Arran. Both sills and dykes are commonly made up of dolerite.
Basaltic flows can be seen where the Antrim lava plateaux formed in Northern Ireland. When
the lava cooled, vertical cracks in the flow resulted in hexagonal columns. There are exposed to
the coast – the Giant’s Causeway. The same volcanic feature can be seen in Fingal’s Cave on the
Isle of Staffa in Scotland
There are no active volcanoes left in the British Isles however there are extinct volcanoes, such
as Arthur’s seat, and castle rock in Edinburgh which were formed by an extinct volcano system
of Carboniferous age (approximately 350 million years old), which was then eroded by a glacier
moving from west to east during the Quaternary (approximately the last two million years),
exposing rocky crags to the west and leaving a trail of material swept to the east. This is how the
Salisbury Crags formed and became basalt cliffs between Arthur's Seat and the city Centre.
Volcanic activity in the UK
MEDC – CASE STUDY
EVENT SUMMARY/INTRODUCTION
• When: 27th September 2014
• Where: the volcano is located on the Japanese island of Honshu which is
around 100km northeast of Nagoya and near 200km southwest of Tokyo
• First fatal volcanic eruption in Japan since the 1991 collapse of a lava
dome at Mount Unseen
• No significant earthquakes to warn
• Hydrothermal explosion where ground water seeps into the volcano and
gets superheated by magma and flashed to steam- phreatic eruption
• Last eruption was 35 years ago
• Ash cloud and low-density, low-temperature pyroclastic density currents
CAUSE: Japan sits on the edge of two conservative plate boundaries which are meeting the
Eurasian plate at a destructive boundary.
As the Pacific plate is pushed into the Earth’s mantle, surface water and hydrated minerals
heat up. Ontake's summit cone was built in a largely buried 4 x 5 km caldera. It lies at the
southern end of the Norikura volcanic zone, which extends northward through Norikura
volcano to Yake-dake volcano. The older volcanic complex of Ontake consists of at least 4
major stratovolcanoes that were constructed from about 680,000 to about 420,000 years ago,
after which On-take was inactive for more than 300,000 years.
Volcano case studies Mt – Ontake
MEDC – CASE STUDY
WHAT WERE THE
EFFECTS/IMPACTS OF THE
EVENT?
Primary:
• 47 people died- many who were
hiking on the mountain itself
• Volcanic bombs
• Hydrogen sulfide gas spewed from
the mountain which suspended
search due to dangerous conditions
• More than 24 bodies remain at the
summit
• Police said that 46 of the 47 victims
were bludgeoned to death by falling
rocks ejected by the eruption and
the other victim died of burns,
although no magma was observed.
MEDC – CASE STUDY
RESPONSES TO THE EVENT?
short term
• Recovery crews have been unable to return, wary of more activity from Ontake as tremors
continue to shake the region.
• Japan Ground Self-Defense Force personnel and firefighters climb the ash-covered slope of
Mount Ontake to rescue people who have been trapped in the mountaintop lodge during the
eruption, one day after the volcano became active in central Japan, on September 28, 2014.
• Day after day, bad weather has hampered the search for survivors and bodies, which may
now lie beneath 30 cm or more of ash.
• Rescue efforts will resume on 29/09/14 after an intense search on 28/09/14 was called off
because of toxic volcanic gases in the area.
• International aid was not required as Japan is an MEDC country and this didn’t affect many
homes.
Long term
• Researchers call for better volcano prediction.
• Not much else has been decided as the volcano only erupted less than a month ago.
Volcano case studies Mt – Ontake
EVENT SUMMARY/ INTRODUCTION
o When: 1995-97
o Where:
- British colony in the Caribbean
- Capital city: Plymouth
o Majority of infrastructure is on the
south of the island
o The volcanic area located in the
south of the island on the Soufriere
Hills is known as Chances Peak
o People live around the volcano due
to agriculture- fertile soils
o Before 1995 it had been dormant for
300 years
o Volcanic Explosivity Index (VEI): 3
o Ejecta volume: more than 10,000,000m3
o Eruption: Vulcanian/Pelean; severe
with a glowing avalanche of hot ash
and pyroclastic flows
o Plume Height: 3-15km
LEDC – CASE STUDY
WHAT CAUSED THE EVENT?
1995: Chances Peak began giving off warning signals like small earthquakes and eruptions of
dust and ash
Destructive plate boundary (North American and Caribbean Plates). The oceanic plate subducts
beneath the continental plate and as it does the pressure increases which triggers earthquakes due
to friction and forms molten magma. The magma tries to rise to the surface and erupts as a
volcano.
Volcano Case Studies-MONTSERRAT
WHAT WERE THE EFFECTS/IMPACTS OF THE EVENT?
LEDC – CASE STUDY
Primary:
2/3 of the island were covered in ash
Volcanic bombs were hurled (5m in size)
Dome collapsed and caused 5 million m3 of ash and dust to cover the surrounding areapyroclastic flow
60% of the housing was destroyed
75% agricultural land destroyed
Airport and port closed
Wildlife destroyed
19 people died
Secondary:
Water supplies were infiltrated leaving a high demand for water
Spread of disease
Many people suffered from severe burns from ash deposits of 1-2cm
8000 refugees left the island but didn’t return
Unemployment rose from 7% to 80%
Population fell over half
Loss of income and tourism
Overcrowding in shelters
Volcano Case Studies-MONTSERRAT
LEDC – CASE STUDY
RESPONSES TO THE EVENT?
Short term:
• Evacuation to shelters
• Provision of basics e.g. food and water
• Capital (Plymouth)- ghost town
• Unemployment
• £41 million in aid from the British Government
Long term:
• Exclusion zone set up around the volcano
• Montserrat police force were sent in to try and find survivors
• 1996: Montserrat Volcano Observatory (MVO) was set up to monitor volcanic
activity and provide future warning systems
• Risk assessment was completed to help islanders understand which areas are at
risk and reduce problems for the future
• New infrastructure was built
• Use of the volcano as a tourist attraction
• Services in the north of the island were expanded
Volcano Case Studies-MONTSERRAT
MEDC – CASE STUDY
• The Yellowstone Caldera is the volcanic caldera and Supervolcano located in Yellowstone
National Park in the United States. The caldera and most of the park is located in the northwest
corner of Wyoming. The major features of the caldera measure about 34 by 45 miles. The caldera
formed during the last of three super eruptions over the past 2.1 million years.
• There are about 40 super volcanoes are dotted across the globe. There are two in Britain – one in
Glencoe, Scotland, the other in Scafell in the Lake District. However, most super volcanoes,
including those in Britain, burned out long ago.
• Yellowstone is a dormant Supervolcano, which means a major eruption could happen in the
future. However most volcano experts say a Yellowstone super-eruption is probably a long way
off, or it may never happen at all.
• About 2.1 m years ago the Yellowstone super volcano erupted 2,500 times more ash than Mount
St Helens
• "It's far more likely, if there is an eruption, it'll be on a small scale, perhaps comparable to Mt St
Helens," says volcano expert Prof. Steve Sparks of the University of Bristol.
• Their main feature is a large magma chamber, which is an underground reservoir filled with
flowing, hot rock under huge pressures.
• A super-eruption would equal the force of 1,000 Hiroshima atomic bombs exploding every
second.
• You could fit Tokyo, the world's biggest city, in Yellowstone's super-volcanic crater.
• Three super-eruptions at Yellowstone appear to have occurred on a 600,000-700,000 year cycle
starting 2.1 million years ago. The most recent took place 640,000 years ago – suggesting
Yellowstone is overdue for an eruption
Yellowstone Supervolcano
YELLOWSTONE
MEDC – CASE STUDY
YELLOWSTONE
MEDC – CASE STUDY
Vulcanicity Quotes
• Mount Aso rumbles to life, sending ash over Kyushu – Japan Times
• Japan volcano eruption hits flights – SKY News AUS
• Nuclear Power Facility To Be Reopened In Japan Despite Volcano Warnings, Could
Cause 'Nationwide Disaster'
• Cape Verde volcano threatens to destroy villages,
• The ash cloud produced by the eruption of a sub-glacial volcano in Iceland brought
chaos to the European air industry (mount E)
• thousands of passengers have had to make their way home overland
• A new eruption at Mount Etna eruption has forced the closure of Catania Airport in
Sicily.
• The beast is risen: Mount Etna's latest eruptive episode
• Europe's most active volcano, Mount Etna, erupts
• Powerful Mount Etna Eruption / Sicily Airport Closed
• Mount Etna Erupts in Fiery Display
• Magnificent Mount Etna Volcano Roaring Lava
• An earthquake is the shaking and vibration of the Earth's crust due to movement of the Earth's
tectonic plates.
• Earthquakes can happen along any type of plate boundary.
• Earthquakes occur when tension is released from inside the crust. Plates do not always move
smoothly alongside each other and sometimes get stuck. When this happens pressure builds up.
When this pressure is eventually released, an earthquake tends to occur.
• The point inside the crust where the pressure is released is called the focus. The point on the Earth's
surface above the focus is called the epicentre.
• Earthquake energy is released in seismic waves. These waves spread out from the focus. The waves
are felt most strongly at the epicentre, becoming less strong as they travel further away. The most
severe damage caused by an earthquake will happen close to the epicentre.
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2G2 – Earthquakes (HOW)
2G2 – Earthquakes Richter
The magnitude value is proportional to the
logarithm of the amplitude of the strongest
wave during an earthquake. A recording of
7, for example, indicates a disturbance
with ground motion 10 times as large as a
recording of 6. The energy released by an
earthquake increases by a factor of 30 for
every unit increase in the Richter scale.
The Mercalli intensity scale is a seismic scale used for measuring the
intensity of an earthquake. It measures the effects of an earthquake, and
is distinct from the moment magnitude usually reported for an
earthquake
2G2 – Earthquakes Mercalli
2G2 – Earthquakes – Case studies
A long, high sea wave caused by an earthquake or other disturbance.
A tsunami is a huge wave, usually caused by volcanic or earthquake
activity under the ocean, which can eventually crash onto the
shoreline. The effects on a community can be devastating.
When an earthquake, volcano or landslide happens on the ocean floor, water is
displaced. This water forms the start of the tsunami.
When the waves reach shallower water:
their height can increase by several metres
the shallow water slows the wave
the waves get closer together
It is hard to see that a tsunami is approaching. The most obvious sign is the coastal
water retreats just before the waves reach the shore. This is actually the trough of the
wave following behind.
Tsunami
Source
LEDC Tsunami
LEDC – CASE STUDY
A decade ago, one of the largest earthquakes ever
recorded struck off the coast of Indonesia, triggering a
tsunami that swept away entire communities around the
Indian Ocean.
The quake ruptured the greatest fault length of any recorded, spanning a distance of an
estimated 1,500km (900 miles) - longer than the US state of California.
The rupture started beneath the quake's epicentre and progressed northward along the
fault at about 2km/sec (1.2 miles/second) - lasting about 10 minutes - according to the
Tectonics Observatory at the California Institute of Technology The length of the
rupture meant that the waves reached a wider geographical area - as far afield as
Mexico, Chile, and the Arctic.
The waves travelled at speeds of up
to 800km/h (500mph).
Computer modelling after the
tsunami, estimated that waves had
reached a height of almost 20m
(65ft) in some areas.
However, scientists investigating
damage in Aceh, Indonesia found
subsequent evidence that waves had
reached 20-30m (65-100ft) in places.
LEDC – CASE STUDY
• The Indian Ocean Tsunami made landfall on 26th December 2004. It
was unprecedented in its scale, destroying parts of Sri Lanka, Indonesia
and Thailand and resulting in over 250,000 deaths within the region.
• The involvement of 30 independent national disaster victim
identification teams placed a strain on the command structure and
process and the necessity to standardize the victim identification process.
• The overall scope of the disaster and the large number of deceased was
overwhelming.
• There was no data management system within Thailand capable of
recording the ante mortem and post mortem information on the
deceased.
• There was pressure either direct or indirect on the various national DVI
teams to expedite the identification of their nationals killed in the
incident.
• The Thai National Police had 3,737 people officially recorded as
missing/deceased.
• Over 30 different countries lost citizens as a result of the tsunami.
LEDC – CASE STUDY
• A quarter of a million people died.
• Two million people were made homeless.
• People were swept away in the waters, which arrived rapidly and
with little warning.
• Thirteen countries were affected, the worst being Indonesia.
• Indonesia was hit by the tsunami first. Fourty-five minutes later
the tsunami reached Thailand.
• Mangrove swamps helped to act as a barrier to reduce the energy
of the water in some areas.
• Short-term aid, such as water purification tablets, temporary
housing and medical supplies were given from international
countries.
• Islands reliant on tourism and fishing, such as the Maldives, had
to rebuild their industries.
• An early warning system between countries surrounding the
Indian Ocean has been set up.
MEDC – CASE STUDY
• The 9.0-magnitude earthquake struck off the coast of Japan on The 11th March 2011
at 0546 GMT
• The quake’s focus was 130 kilometres to the east of the prefecture’s capital, Sendai.
• The resulting tsunami was sent crashing into the country’s north-eastern coast.
• It was originally reported at a magnitude of 7.9, but later was upgraded to 8.9 and
then to a 9.0.
• Which makes it the fifth largest recorded Earthquake worldwide since 1900.
• Japan is located on the plate Margin of the Eurasian Plate and the oceanic Pacific
Plate.
• This plate margin is destructive, friction is present and the plates stick as the Pacific
Plate subducts under the Eurasian Plate.
• When the plates stick, tension builds up. When this pressure builds up and is released,
it causes a rapid shift in the plates (causing the earthquake) and a lot of energy to be
release, in this case about the same as the annual energy output of the UK
MEDC Tsunami – Japan 2011
MEDC – CASE STUDY
• Japan was largely prepared for the earthquake and many buildings remained standing afterwards,
but it was not prepared for the subsequent Tsunami.
• A tsunami warning extended to at least 50 nations and territories, as far away as South America.
• The yen fell sharply but recouped most of its decline several hours later. Tokyo stocks fell.
• 2,000 people confirmed dead
• 10,000 more people expected to be confirmed dead
• 2,000 people injured
• 530,000 people displaced, staying in 2,500 evacuation centres, such as schools and public halls
• 24,000 people still completely isolated and cannot be reached
• 1.2 million homes without power
• 1.4 million homes without water
• 4,700 destroyed houses
• 50,000 damaged houses
• 582 roads cut off
• 32 bridges destroyed
• Tokyo’s major airports halted flights,
• All Tokyo area trains were halted, while The Shinkansen Bullet train service was suspended.
MEDC Tsunami – Japan 2011
MEDC – CASE STUDY
MEDC Tsunami – FUKUSHIMA
• Two nuclear plants on the Pacific coast in Fukushima were automatically
shut down.
• At Fukushima the subsequent tsunami disabled emergency generators
required to cool the reactors.
• Over the following three weeks there was evidence of a partial nuclear
meltdown in units 1, 2 and 3; visible explosions, suspected to be caused
by hydrogen gas, in units 1 and 3; a suspected explosion in unit 2, that
may have damaged the primary containment vessel; and a possible
uncovering of the units 1, 3 and 4 spent fuel pools.
• Radiation releases caused large evacuations, concern over food and water
supplies, and treatment of nuclear workers.
• The IAEA has rated the events at level 7, the same as Chenobyl, and the
highest on the scale – meaning that there is a major release of radio
active material with widespread health and environmental effects.
MEDC Tsunami – Japan 2011
Source
MEDC – CASE STUDY
Market Rasen Earthquake, Lincolnshire (2008)
Background Information
• Location: Market Rasen, Lincolnshore (2008)
• Date 27 Feb 2008
• Time 0057
• Magnitude 5.2
MEDC – CASE STUDY
Causes of the Earthquake
• Why did it happen
• The Earthquake was the result of an old fault line deep below Lincolnshire, it
was caused by a sudden movement along a strike-slip fault.
• What fault line was it on?
• Strike Slip Fault
Impact of the earthquake
• What damage was done
• There were 9 aftershocks, damage included roof tiles coming off, chimney pots
falling down and some unsafe walls/ roofs. Masonry fell from St Thomas church.
No one was killed and one man went to hospital with a suspected broken pelvis
(when he was pinned under masonry in his bedroom)
• Market Rasen now got its very own earthquake monitoring station
Earthquake Management
Prediction:
There is currently no reliable, accurate way to predict an earthquake.
Scientists can however indicate where an earthquake is likely to be found.
Current methods include:
- levelling/ laser reflector – which surveys the movement at a fault line
- Seismometer – which records the shock waves from the epicentre.
- Gravity meter, magnetometer and electrical resistivity meter – properties
of rocks change under stress
- Water table level meter – sudden rise or fall could be caused by
deformation of ground
- Radon gas detector – radon gas is released when rocks such as granite are
deformed
- Satellite surveying
- Seismic records can give us an idea of what to expect in the region.
Earthquakes can only be predicted via observation and in some cases
estimation. Therefore it is unreliable and the best way to mange an
earthquake at the moment is to be prepared for it.
Earthquake Management
Protection/Preparation
Earthquakes can not be predicted accurately or stopped. An earthquake is a force of
nature which we have no power over. Therefore we have to work to protect and prepare
for an earthquake. In earthquake prone regions like Japan many systems have be
implemented to reduce the consequences of an earthquake.
There are 3 main areas of protection:
1. Making buildings and urban areas more earthquake resistant
2. Education
3. Prediction and warning systems
In Japan there are strict building codes in forced by law (2007) to reduce damage during
an earthquake, all buildings must be fire proof. All buildings are also double checked
for safety.
In some cities smart metes have been introduced which shut off gas supplies
automatically during an earthquake or increased seismic activity.
Land use: schools and hospitals are located in safer areas.
Earthquake Management