From the fearsome belly of the earth

Sheel

Have you heard of Mount Yasur? It’s a volcano in a small island country called Vanuatu, located in the South Pacific Ocean, and it has been intermittently spewing ash and gas with the occasional small explosion… since 1774 at least. Yes, that’s right – seventeen-seventy-four, which means it has been active for almost 250 years! And that date is only when it was first sighted by Captain Cook, the British explorer; it’s possible that the activity began much earlier.

Volcanoes, one of Earth’s geological features, often appear to be beautiful mountains, rising high into the sky, with peaks that are covered with snow and sometimes lakes at their bases, or in their craters. They may also be home to a great variety of flora: volcanic soil is the most fertile soil on the planet. However, volcanoes are also very dangerous. An erupting volcano can look like a magnificent fountain of fiery, red-hot lava, or an ash-cloud belching gradient. Lava can potentially jet up to 2000 feet into the air, and a tower of ash can be as tall as 25 miles!

Eruptions take place when hot, molten rock (called magma) from deep inside the earth pushes its way through to the surface as lava, often along with ash, gases and even solid rocks, which spew out into the atmosphere explosively. They can even flow river-like for miles and miles. Volcanoes can cause mudslides and avalanches, earthquakes, and even floods and tsunami. This project takes a close look at volcanoes and outlines activities that teachers can use to help students in middle and high school learn about them over the period of a week. Some activities can be simplified for use at the primary school level as well.

Volcanoes in mythology
The word ‘volcano’ comes from Vulcan, the Roman god of fire. Vulcan was thought to be the god of volcanoes. Depicted as a blacksmith, he was also the god who manufactured weapons and artifacts for other gods and goddesses in his forge, which was thought to be located on the island of Vulcano near Sicily, or on one of the two volcanoes, Mt. Etna on the island of Sicily, or Mt. Vesuvius in Italy. It was believed that when he was angry, he made the volcanoes erupt.

In Icelandic folklore, the volcano Hekla was thought to be an underground channel that connected the world we know to the next world, through which the souls of doomed and unlucky people had to pass as they travelled to hell. Lava and ash were thought to be glimpses of hell. In the Bible, the description of the destruction of Sodom and Gomorrah with a hail of fire and brimstone calls volcanoes to mind, although they are not specifically mentioned, and Satan too is thrown into a lake of fire and brimstone. Thus, volcanoes appear to be associated with punishment meted out by the gods.

History/language activity: 1. Mt. Etna and Mt. Vesuvius are located in the Mediterranean, the birthplace of both the Greek and Roman civilizations. What did the Greeks think about volcanoes? Did they too have a god of volcanoes?

Language/literature/art: 2. There are many other legends about volcanoes, such as the story of Pele, the Hawai’ian goddess who is said to live in the crater of Mauna Lea, or Katla, the witch who became a volcano (Iceland), or the princess who protected her father’s land by becoming a volcano (Irazu, Costa Rica), or the immortal volcano (Mt. Fuji, Japan), or the volcanoes in Kamchatka, Russia, where the gomuls cook their whales. The people of other regions such as the Philippines or Australia too have their own stories. What are their beliefs about volcanoes? You could divide the children into groups of 5 or 6 and get each group to find out about the stories of one region each, illustrating themor preparing to relate them in class as part of a storytelling session. At the primary school level, you could tell the children these stories.

Volcanic activity and new geographies
A volcano is formed when the magma from the mantle of the earth is squeezed out through the harder crust above it. The earth’s crust consists of several tectonic plates, and most of earth’s volcanoes are found at the edges of these plates. They are formed where these plates are moving, either when one plate is being pushedunder the other (subduction) or apart from one another (divergence). Since the tectonic plates float on the mantle of the earth, the hot layer of flexible, flowing rock that’s just below the crust, the movement of the plates creates space for magma to rise and overflow. The magma which flows out is called lava. At the surface, it begins to cool and generally forms a cone around the vent. These cones grow into mountains over time, with every new flow of lava covering a good part of the previous one.

Some volcanoes are found where the crust of the earth is thin – such places, where the magma has been able to push through the crust, are called hotspots. There are many hotspots on the floors of the earth’s oceans, where the crust is thin. Undersea volcanic eruptions occur in such places. Such eruptions have even given rise to new islands. The islands of Hawai’iare actually the peaks of the Hawaiian-Emperor mountain range which rises from the ocean floor in the middle of the Pacific Ocean. These islands are now here close to the edges of any tectonic plate, but about 3,000 kilometres from the nearest continent!

Geography: Divide the children into four groups and engage each group in one of the following activities. They can then present the information to the rest of the class.

There is an interesting correspondence between the geologic history of these islands and some of the Hawai’ian stories and chants, which United States Geological Survey (USGS) geologist Don Swanson believes describe actual volcanic eruptions and other past events. Many scientists now believe that indigenous tales from around the world may have a root in actual events, and scientific evidence has even been found for some. In some countries, petroglyphs have also been carved on some of the ancient volcanic rocks, as in Hawai’i and Mexico. If time permits, you could look them up with the children.

3. On the Internet or in an encyclopaedia, look up tectonic plates and volcanoes. Find out more about how the movement of tectonic plates cause volcanoes to form. A good site from which to learn more about the formation of volcanoes is https://www.nationalgeographic.org/article/plate-tectonics-volcanic-activity/.
4. The largest tectonic plate is the Pacific plate, around which lies a Ring of Fire. What is this Ring of Fire and why it is so named? What are its most fiery outlets?
5. The continent of Africa is slowly breaking into two, and there is a deep rift in the crust where it is breaking. Called the East African Rift System, this region has several volcanoes and lakes. Get the children to find out about them.
6. The island of Surtsey near Iceland was formed by volcanic activity in 1963. Scientists observed how the island was formed and how life forms began to populate the island. Get one group to find out about and present the story of Surtsey.

Types of volcanoes and volcanic activity
One way in which volcanoes are classified is according to the way they were formed. A volcano that has an effusive eruption does not erupt violently but may still throw up lava that flows out steadily and spreads along the ground. Such volcanoes generally have a round and wide shape, like a shield, and are therefore called shield volcanoes. A volcano that erupts explosively throws up not just lava but also ash and rock and grows layer by layer over several eruptions into a tall and conical mountain with steep sides and a flat top. Such a volcano is called a stratovolcano. Since it has many layers, it may also be called a composite volcano.

Volcanoes may also be categorized based on their activity as active, dormant, and extinct. What do these terms mean? Get the children to find out.

Lava from a volcano may be thick and slow to move, flowing so slowly that a human being can outrun it. Or it may be thin and flow rapidly, burning and burying everything in its way in a matter of hours. Sometimes, lava within a flow also moves at different speeds: the lava at the surface and edges might cool down and begin to harden, thus slowing down its movement, while the lava towards the middle of the flow and below the surface continues to flow quickly. This kind of flow can leave behind tunnels that run a long way, called lava tubes. Sometimes, lava might even pour from a lava tube or over a cliff directly into the sea, extending the land and even forming sea arches as the lava cools.

As lava cools, it solidifies into rock. Depending on the kind of flow, solidified lava may look like a pile of huge ropes or cables (called pahoehoe) or like a field of rough rock (called a’a). In some places, lava has cooled in symmetrical columns or blocks of lava, such as in Iceland (Gerðuberg Cliffs) and Ireland (Giant’s Causeway). Under the sea, hot lava can form pillow-like shapes as it meets the cold water, as along the mid-Atlantic Ridge, and volcanic minerals can also form smoking chimneys under the sea. Here’s a very interesting film that the science teacher can view with the students and later discuss: https://www.nationalgeographic.org/media/deep-sea-hydrothermal-vents/.

On land, lava can pile up around the vent and form lava domes. Rocks, pumice, and ash that are blown into the sky can cool in the air and fall around the vent as cinders, forming pyroclastic cones. Pyroclastic material can run swiftly down slopes, destroying the surrounding areas in much less time than molten lava flows. Volcanoes also release some of gases that are formed under the earth, including such poisonous gases as sulphur dioxide, hydrogen sulphide, hydrogen fluoride, and carbon dioxide.

What makes a volcano erupt high into the sky? What are the warning signs before an eruption, and how does the landscape change after one? Use some of the photographs from https://web.archive.org/web/20050921233521/http://vulcan.wr.usgs.gov/Volcanoes/MSH/SlideSet/ljt_slideset.html, a site devoted to Mt. St. Helen’s, to help children understand how a volcano might change before and after an eruption. The slides GS-2, 3, 5, 8, 15 (pyroclastic flow), and 10 (destroyed forest) are particularly useful. Slide 21 shows a new dome formation in Oct 1980 and slide 18 shows a lahar from March 1982.

Science (physics): 7. Try this experiment in class. Against one wall of the classroom, set up a table with a measuring tape on the wall behind it. Bring in five bottles of an aerated drink. In four of the lids, punch a hole each with a hot needle, and tape it up so the fizz doesn’t escape. Make sure that the holes are of four different diameters. Label the bottles in serial order, progressing from the bottle with the tiniest hole to the largest one. The fifth bottle can be marked 5. (You could do this preparation beforehand.) Now, cover the hole of one bottle and shake it vigorously up and down a few times. Place it on the table such that the fizz can rise through the hole and its height can be marked on the tape. Continue this process with each bottle in turn, shaking each one in exactly the same manner as the previous one, and marking the height of the fizz on the tape. End with bottle 5 after taking off its cap completely. From which bottle did the fizz rise the highest? Why? Elicit the answers to this last question from the children, and then tell them how the pressure of the gas affects the height to which the liquid jets up.

Alternately, you could use a drip irrigation kit or even a simple pipe to demonstrate how changes in pressure and the size of the opening impact the flow of liquids. This is the same principle on which geysers and fountains too work.

8. In the primary classroom, bring a bottle of liquid soap or ketchup into the classroom, along with a bottle of water. On each child’s palms, put a few drops of water on one palm and soap/ketchup on the other. Ask them to move their hands about. What happens? Which flows easily, and why? The children may use the words ‘thick’ and ‘thin’ to differentiate between the two. Talk about how the thickness and or density of a liquid affects its flow. You can scale up the activity for middle and high school using a variety of liquids and testing how they flow over a plastic or wooden board: introduce the concept of viscosity.

Once lava has cooled down sufficiently, life forms begin to appear in the area. Longhorn beetles that can survive temperatures of up to 70 degrees centigrade are the first to make a home in warm volcanic soil; they have even inspired scientists to make a new cooling material! Among the plants, it’s the ferns that begin to dig their roots in first. There are many marine animals that make their homes in lava chimneys in the deep sea – the film about hydrothermal vents above offers a view of some of these animals.

There are times when the land surrounding or close to an erupting volcano suddenly sinks. This subsidence happens as the magma from the magma chamber below the volcano empties, and there is nothing to hold up the land above. The depression that is formed in this manner is called a caldera.

Language/geography: 9. There are a great many words that have to do with volcanoes. Get the children to identify some of the vocabulary related to volcanoes, many of which have already been used above. Here are a few more: fissure, fumes, geyser, maar, plume, xenolith, Pele’s hair, Pele’s tears. What do these words mean? You can also use the centrespread for this exercise.

Dramatic devastation
Eruptions are recorded in history in different ways. Oral history is one: there are prehistoric and aboriginal stories that tell about volcanic activity, including from native North America as well as the aboriginal Gugu Badhun from Australia, both over 7000 years old. Some even believe that the myth of Atlantis may be based on the destruction of the prehistoric city of Akrotiri in the Theran eruption of the 16th century BC. An image of an eruption is found on the walls of a cave in Catal Huyuk, dating about 9000 years ago. The oldest depiction of a volcanic eruption, though, may be on the walls of the Chauvet-Pont d’Arc cave in France, which some geologists believe was created about 36,000 years ago.

One of the most vivid descriptions of the destruction caused by a volcano is that of the city of Pompeii, by Pliny the Younger, a statesman of Ancient Rome. Two of his letters refer to the eruption of Mt. Vesuvius in 79 AD. This eruption destroyed the towns of Pompeii and Herculaneum completely.

Language/history: 10. Pompeii, lying to the south of Vesuvius, was destroyed by showers of super hot pumice and ash. Herculaneum which was towards the northwest, was buried by pyroclastic flows. Parts of both towns have been excavated over the last century. Get the children to look up information on these two towns.

11. The manner in which volcanoes can destroy vary. Get the children to find out how the town of Armero in Columbia was destroyed (in 1985), and what the eruption of Mt. Krakatoa in Indonesia did a little over a century before that (in 1883).

Math/geography: 12. Every year, there are close to 60 volcanic eruptions around the world, though not all of them are equally destructive. In groups, students could look up various volcanic eruptions and create a statistical table of the damage caused directly and indirectly:
a. the 10 most deadly eruptions in recorded history.
b. the largest eruptions in the last 10 years.
c. the impact of the 16 ‘decade volcanoes’ in the last five years.

Geography: 13. Earth is not the only place where volcanoes exist. Get the children to look up other places in the solar system where volcanic activity takes place.

They can have column giving details of the name and location of the volcano, the year in which it erupted, the height of the ash cloud or lava jet, the mode(s) of destruction, the extent of damage caused and the estimated losses (in Indian rupees).

Red skies and lavender sun
Apart from the terrifyingly stunning views during and immediately after an eruption, there are sometimes long-lasting effects in the atmosphere too. The eruption of Mt. Tambora in Indonesia in 1815 created such abnormalities in the climate of Europe and North America that 1816 came to be called the ‘Year Without a Summer’: in that year, the crops failed, and the temperature of the planet went down by almost one degree Fahrenheit. The eruption of Krakatoa in 1883, which was one of the most destructive ever recorded, created spectacular sunsets for years afterwards due to the chemicals it released.

What is it like to witness an eruption or its aftermath? Pliny the Younger only described what he saw from a distance, and it is frightening to think of experiencing the same. Yet there are those who choose to follow and be around volcanoes – some to fulfil their sense of adventure, some to capture them on camera, and others to learn and understand volcanoes better.

Volcanologists are people who study volcanoes and include various kinds of scientists as well as laypersons. There are several volcano observatories around the world, in which many kinds of scientists work together to study volcanic activity. The aim is to be prepared for hazardous events and thus save lives. Various kinds of tools are used to monitor volcanoes – in slides 29-31 and 33 in the Mt. St. Helen’s series, one can see a seismic station set up by scientists, gas samples being collected, scientists trying to measure magnetic field strength and the deformation rate of dome, and so on. Nevertheless, volcanology is still a fledgling science, and even the best scientists cannot accurately predict when the next eruption will take place.

For those who want to know more about volcanoes, the global volcanism program run by the Smithsonian Institution (https://volcano.si.edu/) is just the place!

The author is a freelance editor and educator with over two decades of experience working with teachers and children. She can be reached at sheel.sheel@gmail.com.