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Annie Preston

on 1 May 2014

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Transcript of Etna

The city center of Catania sits just over 25 miles away from the summit of Etna.
What makes Etna Unique?
People have inhabited the area around Mt. Etna for thousands of years. The first to write about the eruptions was the Greek historian Diodorus Siculus around 40 BC
Catania, Sicily
Etna sits above the city of Catania, on the island of Sicily. Catania is Siciliy's second largest city.
Emphasis on SIMPLIFIED!

Mount Etna was created by the subduction of the African Plate under the Eurasian Plate. Mount Vesuvius is also along this subduction zone.
There have been historical observations of Etna erupting that go back to 1500 BCE! It is one of the world's longest historically recorded active volcanoes.
Etna: A Stratovolcano
Etna is a stratovolcano, meaning that is a cone-shaped composite volcano. Composite volcanoes are built up by layers and layers of lava flows, tephra, and ash.
Monitoring System
A map of the seismometers on Sicily.
Image from EtnaLive daily photo Ref #16
Image from google maps
This image is the view from the Teatro antico di Taormina, which was an ancient Greek theater built with Etna centered as the backdrop.
Ref #17 Washington's National Gallery, from

Ref #18 From
A map of Etna's Craters:
-Northeast Crater
-Bocca Nuova
-Southeast Crater
-New Southeast Crater
Images from INGV
Ref #10
Annie Preston
Image of Diodorus Siculus Ref #1
Eruptive History!
-Historical observations date back to 1500 BC
-Eruptions even earlier have been confirmed using radiocarbon dating
-Size of the eruptions determines likelihood of there being historical reports of the eruption. The eruption in 1500 BC had a VEI of 5 and has been confirmed through radiocarbon dating of the ash.
Examples of historical eruptions
A combination of historical observations and radiocarbon dating confirm or discredit past eruptions. Ref #14
Largest Eruptions:
Most Explosive:
-1500 BC VEI 5
-122 BC VEI 5
-June 1787 AC VEI 4
Deadliest Eruption in 1669
-Before the eruption, a large earthquake shook Sicily, killing 1,500 people. This eruption was a 3 on the VEI with the resulting lava flow being the deadliest part of the event.
-A group of men outside Catania, dressed in water-soaked cowhide, managed to divert the flow that was heading for the city. They redirected right toward a neighboring city that quickly retaliated against the men. In the end, the flow reached Catania, burning down part of the city, killing 15,000 and leaving thousands homeless.
Agricultural fields on the fertile flanks of Etna are often destroyed by flows
In 1928, the village of Mascali and the surrounding fields were destroyed as a vent opened at the foot of Etna.
Operation Volcano Buster
(Ball, J.)
In 1992 an eruption threatened the town of Zafferana with lava flows down into the Valle del Bove (on the Eastern flank). The town put up dams to stop the flow but they were quickly destroyed by the lava. The U.S. Marines arrived to help, with cargo helicopters dropping large concrete blocks in front of the lava tunnel. This gave them time to dig a trench, diverting the flow away from the town.
Cultural Perspectives
Etna has a strong role in Greek mythology
-Aetna was the mountain-goddess of Etna who is the mother of the Palici by Zeus
-The Palici are the god of thermal geysers
-Zeus buried Typhon, Enceladus, or Briareus under Etna
-Hephaestus and the Cyclops, according to Greek mythology, made thunderbolts for Zeus within the volcano
Etna had influence on Greek poets, such as Hesoid, as it played a role in their narratives of the Greek Gods
Blessing or a Curse?
Many communities around the base of Etna are agrarian-based and benefit from the rich volcanic soil.
These areas have learned, over their long history, how to deal with lava flows.
Infrastructure has been built to divert lava flow, leaving earthquakes as the remaining threat.
Image of barriers built to direct a 1983 flow
Ref #11

Through time, Etna's threat to the villages created instances of strife between communities as they worked to avoid or recover from lava flows.
1669 lava flow covering parts of Catania
Reference # 4

Volcanic Hazards
The towns around Etna are most threatened by basaltic lava flows. Tephra fallout only affects a small area around the craters of the volcano, as the general eruption type is Strombolian, producing small amounts of ash during eruptions.
Small lahars and pyroclastic flows occur only near the craters.
Valle del Bove
-Depression/valley down the E/NE flank of the volcano
-5.5 km across and 1000 meters deep
-Created by a series of landslides caused by gravitational slope failure of an old caldera, called Trifoglietto, that was active between 26,000 and 18,000 YBP (Guest et al.)

2) Azzaro, O., et al. "Forecasting Seismic Scenarios on Etna Volcano (Italy) through Probabilistic Intensity Attenuation Models: A Bayesian Approach." Journal of Volcanology and Geothermal Research 251.February 2013 (2013): 149-157. Print.
3) Bagley, M. "Mount Etna: Facts About Volcano's Eruptions." LiveScience. Feb 25, 2013Web. <>.
4) Behncke, B. "Etna." Italy's Volcanoes: The Cradle of Volcanology.Web. <>.
5) Branca, S., E. De Beni, and C. Proietti. "The Large and Destructive 1669 AD Eruption at Etna Volcano: Reconstruction of the Lava Flow Field, Evolution, and Effusion Rate Trend." Bulletin of Volcanology 75.2 (2013): 1-16. Print.
6) "Diodorus Siculus." Wikipedia. April 14, 2014Web. <>.
7) Di Martino, R., and Camarda, M.: Gurrieri, S.: Valenza, M. "Continuous Monitoring of Hydrogen and Carbon Dioxide at Mt Etna." Chemical Geology 357.24 October (2013)Print.
8) "Etna Volcano." Volcano Discovery. April 22, 2014Web. <>.
9) Guest, J. E., D. K. Chester, and A. M. Duncan. "The Valle Del Bove, Mount Etna: It;s Origin and Relation to the Stratigraphy and Structure of the Volcano." Journal of Volcanology and Geothermal Research 21 (1984): 1-23. Print.
10) INGV. "Active Volcanoes: Etna." Instituto Nazionale di Geofiscia e Vulcanologia. 2014.Web. <>.
11) Oregon State. "Sucessful Lava Diversion, Etna 1983."Web. <>.
12) Pellegriti, D. Mt. Etna. Accessed 4/29/14. PRESENTATION BACKGROUND PHOTO
13) Schellart, W. P. "Mount Etna- Iblean Volcanism Caused by Rollback-Induced Upper Mantle Upwelling Around the Ionian Slab Edge: An Alternative to the Plume Model." Geology 38 (2010): 691-694. Print.
14) Smithsonian Institution. "Volcano Info: Etna." Smithsonian Institution National Museum of Natural History: Global Volcanism Program. 2014.Web. <>.
15) Tarquini, S., and M. Favalli. "Uncertainties in Lava Flow Hazard Maps Derived from Numerical Simulations: The Case Study of Mount Etna." Journal of Volcanology and Geothermal Research 260.June 2013 (2013): 90-102. Print.
16)"Etn@Live: Photo Day." Etna Live. 2014.Web. <>.
17) Washington's National Gallery, <>. Accessed 4/29/14.
18) Ball, J. "Mount Etna- Italy." Geology .com.Web. April 10, 2014 <>.
19) NASA. "Etna eruption seen from the International Space Station." Oct, 2002Web. <>. Accessed 4/29/14.
20) Winster Cavers. "Lava Caves of Sicily." Web. <>
21) Wikipedia. "Stratovolcano." Web. <> Image. Accessed 4/29/14

1) Atsma, A. "Aitna." 2011.Web. <>. Accessed 4/29/14

Etna seen from the International Space Station. Ref #19
Image of Etna behind
Catania. Ref #16
Magma Composition
-Basaltic Magma- the low silica content results in long lava flows, lava tubes, with enough SiO2 for weak Strombolian activity
Lava tube on the flanks of Etna...discovered during construction of the road. Ref #20
Case Study:
1669 Eruption
Branca et al.
-1669 flows analyzed to see flow rates as well as the affects of villages and the city of Catania
-The evolution of the flow field through mapping lava tubes
-75% of flow area covered in first 14 days of eruption (eruption lasted 122 days)
-Flow field from the 1669 eruption showing advancement of flow over time
-Total volume of flow was (607 +/- 105) x 10^6 m^3
-Average thickness was 15.2 meters
-Largest a'a' field by Etna in historic and prehistoric time
-Method for this study can be applied to other basaltic lava flows for hazard analysis
Ref #5
Looking Deeper...
Schellart, 2010
-Etna produced by rollback-induced upwelling of the upper mantle around the subducted Ionian micro-plate edge. The Ionian micro-plate is next the the African plate and both are being subducted. Etna sits along the fault produced by the Ionian plate.
-melting due to upwelling as mantle is forced up by the subducting plate
-Etna is laterally offset from the subduction zone itself, meaning that it is part of the volcanic arc rather than simply on a subduction zone

Ref #21
Highest Volume:
-1669 eruption VEI 3

-Earthquakes are common around Etna due to its position on an active fault
-Having a rapid response program on large volcanoes is important to better deal with the effects of large quakes on surrounding cities
-PROSCEN- software to calculate epicentral intensity and scenarios to track potential hazards
-Etna is extremely well monitored, with the newest software analyzing activity
Earthquake Hazards:
Azzaro et al.
Monitoring of Gases:
Di Martino et al. (2013)
-Hydrogen and Carbon Dioxide levels constantly monitored
-Tailor-made devise created to monitor gas levels from 2009 to 2010
-CO2 showed long-term changes before eruptions, as CO2 is released early in magma ascent
-H2 showed rises immediately before eruptions and is easier to track than O2, as oxygen content is easily contaminated by atmospheric oxygen and magmatic H2 is present at six times greater magnitude than O2
-H2 concentrations ranged from 2 ppm to 150 ppm over the test period
-Updates are available to the public on a weekly basis!
-Latest seismic and activity reading online at
Check it out!
INGV Reports:
WOW! 396 BCE!
VEI of 5!
Last 100 years?
-Keep in mind that Etna is the most active volcano in Europe!
-It has erupted over 70 times in the past 100 years!
Ref #14
Like this lahar! Which occurred near the crater. Make sure your volume is on :)
National Volcano Early Warning System
-Assessment system for a quantitative ranking of potential eruption hazards
-Etna has a threat score of 201! That is very high and means Etna should be very well monitored with a monitoring level of 4!
-Surprise! Etna is the most monitored volcano in Europe!
-Aviation is at high risk during eruptions, with as hazard score of 67.8 as Catania has a large international airport
Most Recent Eruption?
-Effusive and Strombolian activity since January 22, 2014 in the New Southeast Crater
-Lava flows have reached over 3 km down the Valle del Bove
-Etna is a popular tourist destination, with regular tours up to the inactive craters...
Me and my sisters on the rim of a crater- Etna 2008
-There is a large ski resort on the flanks of Etna
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