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By Pascal Gunsch

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TABLE OF CONTENTS Table of contents ............................................................................................................................................... 2

1 Introduction ......................................................................................................................................................... 3 2 Research Question ............................................................................................................................................ 4 3 Theory ..................................................................................................................................................................... 5 4 Strategies ............................................................................................................................................................ 10 5 Planning ............................................................................................................................................................... 10 6 Evaluation & Reflection ................................................................................................................................. 11

Resources ............................................................................................................................................................ 12

The Avellino eruption of 1500 BCE caused a huge exodus of people to the northern Apennines, after which

they are now called.

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Chapter 1

INTRODUCTION

Mount Vesuvius is the only active volcano on the European mainland. It has erupted several times, of which the famous eruption in AD 79, which covered the Roman cities of Pompeii, Herculaneum and Stabiae. During this eruption, a cloud of stones, ashes and fumes was spawned up to 35 kilometres, covering the surrounding in a 3 metre layer of ash. Many people were killed due to the two pyroclastic flows, flows of superheated gas which exceed temperatures of 1000 °C, raging over the ground with speeds of 700 km/h. After this, Mount Vesuvius has erupted several times. The last eruption was in March 1944. This implies that the volcano has not erupted for 65 years. A volcano of the Vesuvius type erupts roughly every 25 years. If this is not the case, each second it lasts longer the eruption will become worse. And, unfortunately, we know for sure that it will erupt. This is not a favourable situation, especially not nowadays. The area around Mount Vesuvius is densely populated, with nearly 3 million people living in the 18 towns in the immediate area, like Naples and Salerno. A new pyroclastic flow would mean the death of at least the 600 000 people living in a 7 kilometre radius from the vent. Others will be affected by the ash clouds and tephra, which can make roofs collapse and pollute the air. The Italian government offers anyone that wants to move out of this area 30 000 euros, in order to decrease the efforts for evacuation plans. They have different evacuation plans based on different models, but a volcano does not only follow models. Heavy eruptions do not occur regularly, and who knows what happens when the top blows off again. By studying the past scientist (and others) hope to be able to predict the future. The volcano has gone through three main phases: In the first phase, lasting from 25 000 to 18 000 years ago, the volcano was building up its edifice with large destructive lava flows. The second phase, from 18 000 years ago till the AD 79 eruption is characterised by the accumulation of gas-rich magma, leading to explosive eruptions. The last phase, form the AD 79 eruption on, the volcano is ‘spreading’, creating new ridges around the base, with large lava flows as a result. The model says that there will no more be explosive eruptions. However, contradicting the model, two explosive eruptions have occurred, namely the one of AD 472, with ash clouds reaching as far as Constantinople, and the one of AD 1631, which indicates that it is hard to predict a new explosive eruption. According to Franco Barberi of Rome University, Mount Vesuvius is the world’s most dangerous volcano, with a high probability of an explosive eruption by the end of the century. Is he right, and if so, what can we do to minimalize the effects?

The 1822 eruption, seen from Naples. Note the ash cloud and rain.

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Chapter 2

RESEARCH QUESTION

Will Mount Vesuvius erupt before AD 2050, and if so, what can we do to minimalize the effects? To answer this question, we must look at various aspects included. At first, we should know how a volcano like Mount Vesuvius works. Why does Mount Vesuvius actually erupt? What influences the intensity of its eruptions? Why is there a regular pattern in volcanic activity? Also we should take previous eruptions into consideration. What were they like? Did the eruptions only affect Italy, or also the rest of Europe? At last, we should take a look at how we can minimalize the effects of an eruption. Where else in the world are volcanoes which are comparable to Mount Vesuvius? How can you predict an eruption? What about the current evacuation plans? When we know this, we can fully answer the question stated above.

‘Vesuvius and Pompei’ by Robert Duncanson.

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Eurasian Plate

Vesuvius

African Plate

Chapter 3

THEORY

Once upon a time there was a volcano. It was called the Mount Somma volcano. Mt. Somma was located on a boundary between two plates. These plates are not static; they move towards each other. This means that either they crush into each other, resulting in the formation of mountains, or they subduct, meaning that one plate goes under the other. In case of Mt. Somma, one plate, the African Plate, is lighter than the other (because it is sea) and therefore it subducts under the Eurasian Plate, on which Italy is located. This convergent boundary produces a lot of molten magma underneath the Eurasian Plate (at the red spot). This magma will rise and ‘burn through’ the crust, until it eventually got so far, that it forms a magma chamber. This chamber will, after some time, build up enough pressure to erupt. Indeed, Somma did erupt several times. The last eruption was about 18 300 years ago. During this eruption, the volcano produced a caldera (comparable to a crater), and out of that caldera came Mt. Vesuvius. Since 1660, regular eruptions have occurred approximately each 25 years. This happens because the magma chamber has to fill and regain enough pressure to break through the mass that obstructs it. The eruption is measured in both magnitude and intensity. Magnitude is size of the eruption, which can be measured as the volume of magma erupted, and the intensity is the rate of magma erupted. The following model shows the different factors that influence the intensity and magnitude of an eruption. Eruption type Large Medium Small Mass eruption rate (intensity) (kg/s) 1.5 ∙ 108 5.0 ∙ 107 1.5 ∙ 107 Conduit length (km) 5 3 3 Conduit diameter (m) 100 60 40 Gas velocity at the vent (m/s) 118 130 135 Pyroclasts velocity at the vent (m/s) 110 115 116 Pressure at the vent (MPa) 1.3 0.96 0.65

1 Subduction. 2 Italian tectonics.

3 The reconstructed Somma volcano.

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Eruptions VEI The VEI (Volcanic Explosivity Index) was designed to identify and classify volcanic eruptions. Mt. Vesuvius knows only two types of eruptions: Strombolian (effusive) and Plinian (explosive). Its largest eruptions were VEI 6. Strombolian eruptions are named after another Italian volcano, the Stromboli. This volcano is characterised by outcoming lava flows. This type of eruption is called an effusive eruption. The other one, a Plinian eruption, is named after the father of volcanology, Pliny the Younger. He was the first one to describe a volcanic eruption, the eruption of 79 AD, which, not only buried the cities of Pompei and Herculaneum, but also killed his uncle. This eruption was an explosive eruption. Most of the eruptions were Strombolian, with lava flows reaching the neighbouring cities of Torre del Greco, San Giorgio, San Sebastiano, Torre Annunziata and Ottaviono. On the other hand, explosive eruptions are less likely to take place. Only 15% of the eruptions in the last 2000 years were Plinian/explosive. However, before that, a lot of Plinian eruptions took place. The first one, the Pomici di Base eruption, took place 18 300 years ago and is classified as VEI 6. The eruption formed the Somma caldera and with it the Vesuvius. 16, 11 and 8 thousand years ago there were eruptions of VEI 5. 3800 years ago, the Avellino eruption took place with VEI 5. This eruption buried Bronze Age settlements and thousands of footprints leading north to the Apennines. After this, the eruption of 79 AD buried the cities of Pompei and Herculaneum. After this, Europe was frequently blanked by Vesuvian ash, with the next major eruptions of 472 and 1631 causing ash to reach as far as the city of Constantinople.

79 172 203 222 303 379 472 512 536 685 787 860 900 968 991 999 1006 1037 1049 1073 1139 1150 1270 1347 1500 1631 1660 1682 1694 1698 1707 1737 1760 1767 1779 1794 1822 1834 1839 1850 1855 1861 1868 1872 1906 1926 1929 1944

All eruptions since AD 79. Explosive eruptions are indicated in bold face.

VEI Name Ejected Volume 0 Hawaiian effusive 1 Hawaiian/Strombolian 0.00001 km³ 2 Strombolian/Vulcanian 0.001 km³ 3 Vulcanian/Peléan 0.01 km³ 4 Peléan/Plinian 0.1 km³ 5 Plinian 1 km³ 6 Plinian/Ultra Plinian 10 km³ 7 Ultra Plinian 100 km³ 8 Supervolcanic 1000 km³

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Volcanoes There are volcanoes that we can compare with Mt. Vesuvius, because they also erupt in VEI 5/6. These are Mt. Tambora, Krakatoa, Mt. St. Helens, Mt. Pinatubo, Sarychev Peak and Eyjafjallajökull. The most recent one, Eyjafjallajökull, is in Iceland. It erupted twice in 2010. The first time, there were only lava flows, so an effusive eruption. 2 days after the last lava flow, the volcano erupted explosively and a huge ash cloud spread over Europe and caused great disruption in air traffic. Sarychev Peak in Russia erupted latest in 2009. This eruption featured a pyroclastic flow. Mt. Pinatubo (Philippines) erupted in 1991. This eruption is so special, because it happened 500 years after the last eruption. The eruption did not only cause huge amounts of tephra (ash, volcanic stones and other ejected ‘litter’) and a pyroclastic flow, but it also meant the end of the volcano. Where once was a mountain, now was a caldera. Mt. St. Helens faced a similar fate as Mt. Pinatubo. In 1980, an earthquake made the north flank of the mountain slide away, lessening the pressure and causing the volcano to erupt. Like Mt. Pinatubo, Mt. St. Helens had been dormant for over 100 years.

Mt. Tambora and Krakatoa, both located in Indonesia, erupted heavily resulting in a caldera. Krakatoa is seen as the heaviest eruption humans have experienced, and Mt. Tambora caused the so called ‘Year without a Summer’. All the scenarios mentioned above are likely to take place. There will definitely be huge ash clouds, a pyroclastic flow and huge destruction. It might even get so far, that the volcano will again collapse into a caldera. At least we can say, that what appears to be dormant can suddenly become active.

1 Eyjafjallajökull’s ash clouds. 2 Sarychev Peak, with a pyroclastic flow. 3 Anak Krakatoa, a volcano within the

caldera of Krakatoa.

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The locations of earthquakes of Vesuvius in the period July-December 2001. The black circles represent earthquakes with a magnitude less

than 1.5, blue circles have a magnitude between 1.5 and 2.5 and red circles have a magnitude

more than 2.5 on the Rigter scale.

Predicting Eruptions The Osservatorio Vesuvio in Naples monitors the volcano. They use seismic and gravimetric stations, a combination of a GPS-based geodetic array and satellite-based synthetic aperture radar to measure ground movement, and by local surveys and chemical analyses of gasses emitted from fumaroles (openings out of which smoke escapes). All of this is designed to track the magma flows inside the volcano. Seismic activity is tracked, because an increase in seismicity generally means an increase in volcanic activity. In addition to this, the epicentre of the earthquake can be of importance: earthquakes generated in the magma chamber are likely to indicate a change. If these waves are harmonic, they indicate the movement of and pressure exerted by magma.

Gasses indicate the presence of magma. Just like when you open a bottle of soda, and bubbles escape, so do other gasses escape when magma nears the surface. One of these gasses is sulphur dioxide. Prior to, for example, Mt. Pinatubo’s eruption in 1991 the concentration of sulphur dioxide increased, while the concentration of other gasses, such as methane and hydrogen gas, decreased. The concentration of these gasses can increase, but also decrease. This might indicate that gas passages are stuck and that pressure increases. Ground monitoring is used to detect anomalies in the surface. If the surface swells, it generally means an increase of magma that is near the surface. Another way to see if magma is near the surface, is by measuring the temperature of the water, which will increase due to the hot magma.

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Evacuation The current government emergency plan for an eruption is made for eruptions up to VEI 4. They assume that pyroclastic flows will occur on the slopes of Mt. Vesuvius, which extend about 7 km. The rest of the so called ‘zona rossa’ (red zone) will suffer from great tephra falls, which will probably make buildings and houses collapse. Because of prevailing winds, those living south-east of are at a higher risk than those to the north-west. Fortunately, this is where the biggest city, Naples, is situated. However, to other major cities, Avellino and Salerno, lie to the south-east of the volcano. When an eruption will is foreseen, the 600 000 people living in the ‘zona rossa’ will be evacuated to other places rather than the ‘safe’ surroundings of the volcano. Since it is better to prevent rather than resolve, the Italian government is making a lot of efforts to reduce the population living in the ‘zona rossa’. This is done by demolishing illegal buildings, change the area into a natural park, and by offering financial incentives (up to € 30 000) for people who will move out of the area. Several scenarios are likely to take place. An upcoming eruption might feature lava flows, ash clouds, pyroclastic flows, or at worst, the top could be blown off again. The volcano threatens the lifes of 3 million inhabitants living in the immediate area, as well as anyone else living in Campania and the neighbouring areas. At least we know that cunning volcanologists guard the volcano.

A tree representing the different scenarios.

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Chapter 4

STRATEGIES Generally speaking, there are two ways to predict an eruption. The first one says that if values such as temperature, surface structure and gas composition change, it is likely that an eruption will take place. The other way to predict an eruption, is by treating the volcano as a patient in a hospital. By analysing a patient’s history and symptoms, one can conclude a disease/malfunction. In the case of volcanoes, one can predict an eruption. By combining the two techniques, you will be able to predict the coming eruptions even better. To do this, one should first gather information on the history of the volcano. Previous eruptions should be analysed both on intensity and magnitude, as well as on values such as gas composition and seismicity. Secondly, one should gather information about the current state of the volcano. One should find what all the values are like today and how they change over time. After this one can compare the values and make different models, such as ‘when the seismicity increases, … is likely to occur’ using these models, an actual eruption could be predicted, either short before the eruption or concerning the far future. If one knows what type of eruptions can be expected, one can anticipate on that and think about resolutions.

Chapter 5 PLANNING

Firstly, the information should be gathered. Information on the history of the volcano and the values nowadays can easily be retrieved from work of others, which should be carefully read and analysed. The time needed to do this depends on how difficult and thick the works are. Nevertheless, it will not be done within a week or 5. After this, the information should be put together into models. This will roughly take as much time as gathering the information. When all the models are ready, the values should be filled in and a prediction can be made. Using this prediction, one can find out whether Mt. Vesuvius will erupt soon and what type of evacuation is needed.

Mt. Vesuvius hiking trail.

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Chapter 6 EVALUATION & REFLECTION

Finding a problem was probably the hardest thing to do. In the world of geography there are a lot of problems, and a lot of them are interesting. However, in the end I chose for the problem of Mt. Vesuvius, since I once visited it. After this, I had to make the research question. That was luckily not as difficult as finding a problem. After that, it was just googling information and finding good websites. Most of the sources are made by official instances such as the USGS and ERUPT, since I believe that they are amongst the most reliable on the internet. Following the theory came the strategies and planning. The strategy, analysing observations as if the volcano were a patient in a hospital, was chosen because it is the best way to predict events: by looking at past and present conditions and how they are related to each other. I have learned some Italian due to the fact that most of the sites were in Italian, and of course about Mt. Vesuvius and volcanism in general, but apart from that I have learned to organise facts and figures, and to judge resources, and to make a better planning. Apart from the fact that I learned from making this project, I also enjoyed making it, as it is an nice and educating assignment.

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RESOURCES http://theory.uwinnipeg.ca/mod_tech/node194.html http://geology.com/volcanoes/vesuvius/ http://www.cuca.k12.ca.us/rcms/smith/volcano/erupt.htm http://en.wikipedia.org/ http://www.geotimes.org/apr05/NN_Vesuvius.html http://www.westnet.com/~dobran/index.html http://www.ov.ingv.it/ov/en/vesuvio.html http://digilander.libero.it/meteo_ercolano/vesuvio.html http://www.usgs.gov/ http://library.thinkquest.org/C0112681/sitemap.htm http://web.archive.org/web/20110614222138/http://www.ov.ingv.it/inglese/vesuvio/vesuvio.htm http://www.vesuvioinrete.it/e_storia.htm http://www.westnet.com/~dobran/gvs.html http://books.google.nl/books?id=3bOo5ZnhHhYC&lpg=PP1&hl=nl&pg=PP1#v=onepage&q&f=false http://www.volcano.si.edu/world/eruptioncriteria.cfm#VEI http://images.google.com/ All pages were last retrieved 29 april 2012.