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A2 Geography Case Study: Mount Etna and Chaiten eruption

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pop taytay

on 9 May 2015

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Transcript of A2 Geography Case Study: Mount Etna and Chaiten eruption

Etna: A decade volcano in Sicily, Italy. (MEDC)
Volcanic Eruptions: Social, Economic and Environmental
1669: Etna's most powerful recorded eruption
In the last 20 years all deaths on Etna have been due to lightening strikes and accidents.
Estimated 77 confirmed deaths, with the majority of these being caused when visitors strayed into hazardous areas.

9 tourists killed in 1979 near Bocca Nuova
Background on the Volcano
Decade volcano: 17 volcanoes identified by
the International Association of Volcanology and Chemistry of the Earths Interior (IAVCEI) as being worthy of particular study in light of their history of large, destructive eruptions and proximity to populated areas.

Europe's highest (3,310m) and most active volcano

Has a volcanic history stretching back over 5,000 years

Nearly 25% of Sicily lives on its slopes (Due to the lower parts of the mountain floor being rich in volcanic soil, the fertile soil is great for agriculture)

Well monitored

Lies on a destructive plate boundary between the Eurasian and African plate

It's a composite cone volcano, meaning its made of layers of rocks and ash which have settled on it from repeated eruptions

Emits basaltic lava which has a low viscosity (Flows move over large distances in short spaces of time)

Has been erupting at least one a year since 2001

-Extensive lava flows flow from Etna engulfed the village of Nicolosi (31.8km away from Etna) Explosions destroyed part of the summit and lava flows from a fissure on the volcano's flank reached the sea and the town of Catania, more than ten miles away. This eruption was also notable as one of the first attempts to control the path of flowing lava.
The Catanian townspeople dug a channel that drained lava away from their homes, but when the diverted lava threatened the village of Paterno, the inhabitants of that community drove away the Catanians and forced them to abandon their efforts

30th October 2002: biggest eruption for many years
An earthquake of 3-4 on the Richter scale, seriously damaged many villages in the eastern area of Etna.
Lasted 7 days.
Seismic activity in this eruption caused the eastern flanks of the volcano to slip by up to 2 meters, and many houses on the flanks of the volcano experienced structural damage.
A column of ash deposited material as far away as Libya (600km to the south)
Eruption destroyed the tourist station, the airport of Sicily's second city, Catania was forced to close as runways were cleared of ash.
Winter tourist industry was affected as visitors stayed away due to safety concerns.
Ski resort destroyed
Dams of soil and volcanic rock were put up to protect the tourist base at Rifugio Sapienza and helped divert the flow
Government pledged to immediate financial assistance of more than $8m and tax breaks to those effected
September 2007

Violent eruptions from the south east crater saw lava spewing up to 400m into the air. Strong wings sent ash and smoke to towns below, meaning the Catania airport had to close.
May 2008
Flurry of earth quakes accompanied by opening of new fissures and the eruption of lava flows that traveled some 6km down the Valle Del Bove.
Monitoring and Management!
Physical characteristics of Etna
How the locals cope:
Rebuild their homes from salvaged materials.

Management of the hazard and responses to the event
-Local people have rebuilt their homes from salvaged materials or relocated elsewhere
- Government intervention has been rare.

-Zafferana was threatened by lava flows.
-Initial attempts at stalling the lava flow failed
-To disrupt and re-direct the flow, explosives were used near the source of the lava flow.

The main eruption in 1992 destroyed the lava tube and forced lava into a new artificial channel

During the 2002 eruptions, dams of soil and volcanic rock were put up to protect the tourist base at Rifugio Sapienza and helped to divert the flow.
The Italians army's heavy earth moving equipment was bought in to block and divert lava flows. (Only losses in agriculture and tourism)
Geochemical Monitoring programs:

Test gas and fluid emissions to help predict new eruptions. The SO2 (Sulfur dioxide) in the volcanic plume is monitored as it can indicate when magma is coming to the surface, and how much magma is possibility coming to the surface.

Mount Etna requires continuous monitoring due to many people living on the flanks of the volcano, and to predict future eruptions even when the volcano is not showing visual signs of an up and coming eruption.
Video about the Instituto Nazionale di Geofisica e Vulcanologia (INGV)
The INGV have been monitoring the volcano for 20 years with a permanent network of remote sensors connected in real time, by radio and or mobile phones.
- Data continuously recorded by permanent stations are also integrated with discrete observations, surveys, and laboratory analysis to evaluate real time the activity level of the volcano and issue warnings.

INGV have more than 78 seismic stations along the eastern coast of Sicily, with more than 60% of them being located on Mount Etna. The stations are deployed around summit craters at different altitudes in order to reconstruct the movement of magma and fluids, plus to see if there's a change in the position of magma from depth to the surface
Thermal Imaging
Useful to study the presence of a fracture, which potentially could be a path for magma. This shows you the regions which are potentially more dangerous. If the path is seen to lead to places of development and where the tourists are, measures can be put in place to try and divert the lava flow
Chaiten Eruption: South-eastern Chile, Friday the 2nd of may 2008 (LEDC)
Described as a Caldera volcano (These are the most powerful and catastrophic types of volcanoes. A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption)

On a destructive margin

Erupted because the denser Nazca plate was sub ducting beneath the South American plate. As the plate descends it causes earthquakes in the Benioff zone.

The lava is Rhyolitic, has high gas pressure and high Silica content (Explosive!)

Chaitén is also part of the world’s longest fold mountain chain, the Andes Mountains, which are crumpled up be the tectonic forces pushing these 2 plates together. In this southern part of the subduction zone the oceanic plate dips at a steep angle, while the northern end may be experiencing flat-slab subduction This low angle of subduction may explain the relative lack of volcanic activity in the northern part of Chile, compared to the extremely active southern volcanic mountains, which was the cause of the Chaitén eruption
Chile is vulnerable to earthquake and volcanic events because of its tectonic setting at a subduction zone. The Andes mountain chain has over 40 active volcanoes and 122 in total, so this part of the world is vulnerable to this type of hazard. In addition, regular passing storms from polar regions mixed with the ash to make the hazard even worse, creating lahars and river flooding as a result.

Erupted for the first time in around 9,400 years!

The Event: Physical and
volcanic processes
The initial eruption produced a plume of volcanic ash and steam that rose nearly 17km high. Winds carried the plume east, over the Andres, into Argentina and over the Atlantic. Lasted 6 hours.

The first earthquakes were felt late on the 30th of April 2008

Nearly continuous ash emissions as high as 30km with intermittent large explosions continued between the 2nd and the 8th of May.

Produced numerous plumes, pyroclastic flows, minor earthquakes and lahars, and building a new lava dome on the north side of the old one. By late May the lava eruptions had created a new dome of 540,000m2 containing 55million m3 of material.

VEI of 4 (Volcanic Explosivity Index) (How much volcanic material was thrown out)

Effects on/actions of people
This area of Chile has reasonably low population density, so limits the potential impacts on the local scale. Only the towns of Chaitén and Futaleufu are in the vicinity.

The town of Chaiten with a populatio4,200 situated 10km south-west of the volcano were
blanketed with ash.

About 4000 people were evacuated by boat along with another 1,000 from Futaleufu

Smaller settlements to the south-eartn such as Chubut received heavy ashfalls.

Ash plume was so thick in some parts of Argentina that flights were divd airports, highways and schools were forced to close.

Lahars generated by the intense rainfall mixing with the ash cut communications

Ashfalls of up to 15cm deep blocked rivers and contaminated groundwater supplies (Residents told not to drink water)

Chilean government distributed fresh water and protective masks

By May 14th it was announced that around 90% of the town of Chaiten was flooded due to
increased flows of the Rio Blanco or Rio Chaiten.

1 death due to stress

Farm animals killed by ash

Local hospitals treating people for breathing difficulties

80-90% of the town reported damaged

20-30% completely destroyed

Extensive damage to airports and marine facilities hindered rescue operations

By May 3rd the Chilean Navy helped evacuate 3,9000 people

Government issues a monthly disaster stipend per month per family and financial aid to small businesses

90 day freeze on payment of existing loans

Social, Environmental and Economic!
Capacity to cope
Chile only has 20 volcanoes with completed geological studies, 7 which
have had hazard assessments and 7 more that are monitored. Chaitén was classified as a low threat volcano, but even without this low rating there is only one volcano observatory in all of Chile, this affects the prediction of such events. The remote location of the volcano and the low population density meant that the management of this volcano was not high, despite its long term explosive past. This eruption had no real time monitoring of its eruption until a foreign agency, the USGS, arrived on the 16th of May 2008, a full 15 days after the first eruption. Thus, it can be argued that prediction, preparation and prevention of this hazard were poor. Chile has got armed services however, and these would be instrumental in aid to the region, and Chile has a stable democratic government.

Prior to 2008, Chaiten was classfied as a low threat volcano. While geological records indicated that it had a history of explosive eruptions, dome building and pyroclastic flows assocaited with the dome collapse, the length of time it had been dormant meant it was not activity monitored (LIKE ETNA!!)

Chile has the largest copper mine in the world and extensive fruit and veg exports, bringing in considerable large amounts of money for the economy, being 1/3 of the GDP. (Eruption caused damaged to the economy, but Etna's economy wasn't so vulnerable)
The long term response to this eruption was that Chile's geological survey (the Servicio Nacional de Geología y Minería, or SERNAGEOMIN) created a new program to improve monitoring and hazard mitigation at 43 of Chile's high-threat volcanoes. The program will support studies of the history of eruptions at these volcanoes, assessments of volcanic hazards, and the creation of a real-time monitoring network and early warning system.
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