Volcanoes

Volcanoes have existed for millennia, malevolent and monolithic, deadly and awe-inspiring, a tool of destruction and creation. They played a large part in the creation of the Earth, and provide the human race with an abundance of wealth, and an equal amount of danger. Humans have always been fascinated by volcanoes, conducting research into them and in many cases venerating and worshiping them because of their power. Although volcanoes are without a doubt incredibly dangerous, they still have their benefits. In this essay I will discuss how volcanoes form, how they behave, and what cultural and religious significance they have for many cultures.

A volcano is described as an opening in the Earth’s crust that allows magma from below the crust to rise to the surface. Volcanoes can form both on land and underwater, and usually form at the boundaries between separating or colliding tectonic plates. If the plates separate (move away from each other), it creates an opening that allows magma to rise to the surface. If they collide, one plate usually sinks below the other in a process called subduction and becomes molten, and the resulting magma then rises to the surface through the gap between the plates. Over several eruptions, the ash and lava that the volcano ejects builds up and hardens to form a cone or mound shape around the opening. If you’re wondering what the difference is between magma and lava, magma is molten rock formed underneath the Earth’s surface, and lava is magma that has flowed out onto the surface. Lava comes in two different varieties, the smooth, steady flowing pahoehoe lava and the coarse, rough, surging aa lava, named in regard to the noise you would make if you stepped on it. Moving back to volcanoes, there are two distinct types, the most common of which are stratovolcanoes. Stratovolcanoes, also called composite volcanoes, are composed mainly of layers of equal amounts of lava and pyroclastic material, and look like a steep cone. The lava they produce is cool and viscous, which means that gases can build up and cause explosive eruptions. Mt. St. Helens is a notable stratovolcano. The other, less common type of volcano is the shield volcano. Shield volcanoes are composed of almost entirely basalt, and are formed by very fluid lava. The majority of the volcano ends up being made of lava, with a small percentage of pyroclastic material. While stratovolcanoes look more like the classic volcano, made up of a cone with steep sides, shield volcanoes tend to be more wide than they are high, with a less steep incline, and are some of the world’s largest volcanoes.

Now that we know how volcanoes are formed, the next question is how do they behave? Volcanoes are usually classified as either active, dormant, or extinct. Active volcanoes erupt regularly, dormant volcanoes still have a chance to erupt but are currently “sleeping,” and extinct volcanoes no longer have any chance of erupting, although this last classification isn’t definitive. One “extinct” volcano erupts every five years on average. Volcanoes either experience violent, explosive eruptions or less explosive, effusive eruptions that cause widespread lava flows. Eruptions can be deadly because they eject a large amount of material that is very hot and very dangerous. Tephra is the term used for all the material ejected from a volcano when it erupts, excluding lava. The more common types of tephra are ash, blocks, and bombs. Ash is a very fine, suffocating powder, blocks are large boulders ranging from the size of a baseball to the size of a house, and bombs are rocks that still have a molten core and can explode and spew lava on impact. Blocks and bombs are usually hurled out of volcanoes with great force, and can reach an initial speed of up to 1,000 miles (1,609 kilometers) per hour. Another danger of volcanoes is that they can cause pyroclastic flows, which consist of large quantities of hot ash, pumice, rock fragments, crystals, glass shards, and volcanic gas. These flows can reach speeds of up to 100 miles (161 kilometers) per hour, burning everything in their path, and a more energetic form of pyroclastic flows, called a pyroclastic surge, has enough energy and speed to ride up and over ridges. Taking into account all these risks, you might be wondering why anyone would want to live anywhere near a volcano. The truth is that, aside from the obvious dangers, volcanoes also provide a lot of benefits. For a start, volcanic gases helped form the atmosphere when the Earth was young, and today volcanoes still provide a number of gases that are necessary for sustaining life. When a volcano erupts it sprays large quantities of minerals out over the surrounding area, which, over time, makes the soil very fertile and perfect for farming, and eruptions also produce valuable resources such as magnesium and iron. Pillars of ash formed during eruptions can reflect some of the Sun’s rays back into space, which has a cooling effect on the planet. Underwater volcanoes can even form new land when they break the surface of the ocean, and over time they can become habitable islands. While volcanoes have dangerous aspects, they can also do a lot of good, but should still be treated with caution.

Because of their violent and impressive eruptions, many ancient cultures believed that volcanoes were gods, or at least controlled by gods. This led to them worshiping and sacrificing to volcanoes in an attempt to appease them. After a period of scientific research of volcanoes, this superstition resurfaced during the Middle Ages, until scientific research resumed in the Renaissance. Even today, many cultures still venerate volcanoes. In May 2006, at Merapi volcano in central Java, scientists warned the locals that the volcano was about to erupt. Meanwhile, in a nearby village, the villagers lit incense and placed rice, fruit and other offerings in small boats and sent them down the river. It was a ceremony to appease the volcano and prevent it from destroying their villages. Because of their faith in these ceremonies and sacrifices, officials were having trouble persuading the villagers to clear out. Many cultures view volcanic activity as an act of justice. To the Aztecs, who were suffering under the conquistadors, Momotombo, a volcano located near the edge of lake in Nicaragua, was the ultimate symbol of defiance. It was said that the ground shook and the volcano roared whenever a Spanish priest tried to approach it. In the Philippines, the Aeta saw the 1991 eruption of Pinatubo as nature’s rebellion against the government giving permission for geothermal drilling and the use of the area for bombing practice. Other cultures view volcanic activity as warnings, such as in another part of the Philippines, where village elders said that recent eruptions were because God was displeased with the laziness of their young men. However, not all cultures see volcanic activity as destructive acts of vengeance. In Africa, the Maasai venerate the volcano Oldonyo-Lengai (“Mountain of God”) as the giver of all good things. Hawaiians see eruptions as acts of creation, and are well aware that they enrich the soil of the surrounding area. Many scientists are still baffled and frustrated by the misguided beliefs that some cultures have about volcanoes, but myth and ritual have a strong root in many cultures, and it helps them cope with disaster.

In conclusion, volcanoes are impressive displays of the power of nature. They are formed when an opening in the crust appears and allows magma to the surface, and gradually grow over time as volcanic material builds up around them. They are a constant source of danger to nearby people, but are also a source of many kinds of wealth. Because of their impressive power, many cultures worshiped and venerated them, and still do to this day. For centuries volcanoes have captured the imaginations of the human race, and they still provide us with danger, wealth, and an incredible spectacle.
 
References
 
Barnes-Svarney, Patricia, and E. Svarney, Thomas. 2004. The Handy Geology Answer Book. Canton, MI: Visible Ink Press.
 
Phys.org: What are the benefits of volcanoes? March 21, 2016. Fraser Cain; [accessed June 5, 2024]. phys.org.
 
American Scientist: Volcano Myths and Rituals. John Dvorak; [accessed June 5, 2024]. americanscientist.org.