What Are The Benefits Of Volcanoes?

Volcanoes are renowned for their destructive power. In fact, there are few forces of nature that rival their sheer, awesome might, or have left as big of impact on the human psyche. Who hasn’t heard of tales of Mt. Vesuvius erupting and burying Pompeii? There’s also the Minoan Eruption, the eruption that took place in the 2nd millennium BCE on the isle of Santorini and devastated the Minoan settlement there.

In Japan, Hawaii, South American and all across the Pacific, there are countless instances of eruptions taking a terrible toll. And who can forget modern-day eruptions like Mount St. Helens? But would it surprise you to know that despite their destructive power, volcanoes actually come with their share of benefits? From enriching the soil to creating new landmasses, volcanoes are actually a productive force as well.

Soil Enrichment:

Volcanic eruptions result in ash being dispersed over wide areas around the eruption site. And depending on the chemistry of the magma from which it erupted, this ash will be contain varying amounts of soil nutrients. While the most abundant elements in magma are silica and oxygen, eruptions also result in the release of water, carbon dioxide (CO²), sulfur dioxide (SO²), hydrogen sulfide (H²S), and hydrogen chloride (HCl), amongst others.

In addition, eruptions release bits of rock such as potolivine, pyroxene, amphibole, and feldspar, which are in turn rich in iron, magnesium, and potassium. As a result, regions that have large deposits of volcanic soil (i.e. mountain slopes and valleys near eruption sites) are quite fertile. For example, most of Italy has poor soils that consist of limestone rock.

The area around the volcano is now densely populated. Credit: Wikipedia Commons/Jeffmatt
The area around the volcano is now densely populated. Credit: Wikipedia Commons/Jeffmatt

But in the regions around Naples (the site of Mt. Vesuvius), there are fertile stretches of land that were created by volcanic eruptions that took place 35,000 and 12,000 years ago. The soil in this region is rich because volcanic eruption deposit the necessary minerals, which are then weathered and broken down by rain. Once absorbed into the soil, they become a steady supply of nutrients for plant life.

Hawaii is another location where volcanism led to rich soil, which in turn allowed for the emergence of thriving agricultural communities. Between the 15th and 18th centuries on the islands of Kauai, O’ahu and Molokai, the cultivation of crops like taros and sweet potatoes allowed for the rise of powerful chiefdoms and the flowering of the culture we associate with Hawaii today.

Volcanic Land Formations:

In addition to scattering ash over large areas of land, volcanoes also push material to the surface that can result in the formation of new islands. For example, the entire Hawaiian chain of islands was created by the constant eruptions of a single volcanic hot spot. Over hundreds of thousands of years, these volcanoes breached the surface of the ocean becoming habitable islands, and rest stops during long sea journeys.

This is the case all across the Pacific, were island chains such as Micronesia, the Ryukyu Islands (between Taiwan and Japan), the Aleutian Islands (off the coast of Alaska), the Mariana Islands, and Bismark Archipelago were all formed along arcs that are parallel and close to a boundary between two converging tectonic plates.

The island of Santorini, Greece. Credit: EOS/NASA/ Public Domain
The island of Santorini, Greece. Credit: EOS/NASA/ Public Domain

Much the same is true of the Mediterranean. Along the Hellenic Arc (in the eastern Mediterranean), volcanic eruptions led to the creation of the Ionian Islands, Cyprus and Crete. The nearby South Aegean Arc meanwhile led to the formation of Aegina, Methana, Milos, Santorini and Kolumbo, and Kos, Nisyros and Yali. And in the Caribbean, volcanic activity led to the creation of the Antilles archipelago.

Where these islands formed, unique species of plants and animals evolved into new forms on these islands, creating balanced ecosystems and leading to new levels of biodiversity.

Volcanic Minerals and Stones:

Another benefits to volcanoes are the precious gems, minerals and building materials that eruptions make available. For instance, stones like pumice volcanic ash and perlite (volcanic glass) are all mined for various commercial uses. These include acting as abrasives in soaps and household cleaners. Volcanic ash and pumice are also used as a light-weight aggregate for making cement.

The finest grades of these volcanic rocks are used in metal polishes and for woodworking. Crushed and ground pumice are also used for loose-fill insulation, filter aids, poultry litter, soil conditioner, sweeping compound, insecticide carrier, and blacktop highway dressing.

The roof of the Pantheon, as seen from nearby rooftops in Roe. Credit: Public Domain/Anthony Majanlahti
The roof of the Pantheon, as seen from nearby rooftops in Roe. Credit: Public Domain/Anthony Majanlahti

Perlite is also used as an aggregate in plaster, since it expands rapidly when heated. In precast walls, it too is used as an aggregate in concrete. Crushed basalt and diasbase are also used for road metal, railroad ballast, roofing granules, or as protective arrangements for shorelines (riprap). High-density basalt and diabase aggregate are used in the concrete shields of nuclear reactors.

Hardened volcanic ash (called tuff) makes an especially strong, lightweight building material. The ancient Romans combined tuff and lime to make a strong, lightweight concrete for walls, and buildings. The roof of the Pantheon in Rome is made of this very type of concrete because it’s so lightweight.

Precious metals that are often found in volcanoes include sulfur, zinc, silver, copper, gold, and uranium. These metals have a wide range of uses in modern economies, ranging from fine metalwork, machinery and electronics to nuclear power, research and medicine. Precious stones and minerals that are found in volcanoes include opals, obsidian, fire agate, flourite, gypsum, onyx, hematite, and others.

Global Cooling:

Volcanoes also play a vital role in periodically cooling off the planet. When volcanic ash and compounds like sulfur dioxide are released into the atmosphere, it can reflect some of the Sun’s rays back into space, thereby reducing the amount of heat energy absorbed by the atmosphere. This process, known as “global dimming”, therefore has a cooling effect on the planet.

Sarychev volcano, (located in Russia's Kuril Islands, northeast of Japan) in an early stage of eruption on June 12, 2009. Credit: NASA
Sarychev volcano, (located in Russia’s Kuril Islands, northeast of Japan) in an early stage of eruption on June 12, 2009. Credit: NASA

The link between volcanic eruptions and global cooling has been the subject of scientific study for decades. In that time, several dips have been observed in global temperatures after large eruptions. And though most ash clouds dissipate quickly, the occasional prolonged period of cooler temperatures have been traced to particularly large eruptions.

Because of this well-established link, some scientists have recommended that sulfur dioxide and other  be released into the atmosphere in order to combat global warming, a process which is known as ecological engineering.

Hot Springs And Geothermal Energy:

Another benefit of volcanism comes in the form of geothermal fields, which is an area of the Earth characterized by a relatively high heat flow. These fields, which are the result of present, or fairly recent magmatic activity, come in two forms. Low temperature fields (20-100°C) are due to hot rock below active faults, while high temperature fields (above 100°C) are associated with active volcanism.

Geothermal fields often create hot springs, geysers and boiling mud pools, which are often a popular destination for tourists. But they can also be harnessed for geothermal energy, a form of carbon-neutral power where pipes are placed in the Earth and channel steam upwards to turn turbines and generate electricity.

Steam rising from the Nesjavellir Geothermal Power Station in Iceland. Credit: Gretar Ívarsson/Fir0002
Steam rising from the Nesjavellir Geothermal Power Station in Iceland. Credit: Gretar Ívarsson/Fir0002

In countries like Kenya, Iceland, New Zealand, the Phillipines, Costa Rica and El Salvador, geothermal power is responsible for providing a significant portion of the country’s power supply – ranging from 14% in Costa Rica to 51% in Kenya. In all cases, this is due to the countries being in and around active volcanic regions that allow for the presence of abundant geothermal fields.

Outgassing and Atmospheric Formation:

But by far, the most beneficial aspect of volcanoes is the role they play in the formation of a planet’s atmosphere. In short, Earth’s atmosphere began to form after its formation 4.6 billion eyars ago, when volcanic outgassing led to the creation of gases stored in the Earth’s interior to collect around the surface of the planet. Initially, this atmosphere consisted of hydrogen sulfide, methane, and 10 to 200 times as much carbon dioxide as today’s atmosphere.

After about half a billion years, Earth’s surface cooled and solidified enough for water to collect on it. At this point, the atmosphere shifted to one composed of water vapor, carbon dioxide and ammonia (NH³). Much of the carbon dioxide dissolved into the oceans, where cyanobacteria developed to consume it and release oxygen as a byproduct. Meanwhile, the ammonia began to be broken down by photolysis, releasing the hydrogen into space and leaving the nitrogen behind.

Another key role played by volcanism occurred 2.5 billion years ago, during the boundary between the Archaean and Proterozoic Eras. It was at this point that oxygen began to appear in our oxygen due to photosynthesis – which is referred to asthe “Great Oxidation Event”. However, according to recent geological studies, biomarkers indicate that oxygen-producing cyanobacteria were releasing oxygen at the same levels there are today. In short, the oxygen being produced had to be going somewhere for it not to appear in the atmosphere.

Roughly 2.5 billion years ago, towards the end of the Archaean Era, oxidation of our atmosphere began. Credit: ocean.si.edu
Roughly 2.5 billion years ago, towards the end of the Archaean Era, oxidation of our atmosphere began. Credit: ocean.si.edu

The lack of terrestrial volcanoes is believed to be responsible. During the Archaean Era, there were only submarine volcanoes, which had the effect of scrubbing oxygen from the atmosphere, binding it into oxygen containing minerals. By the Archaean/Proterozoic boundary, stabilized continental land masses arose, leading to terrestrial volcanoes. From this point onward, markers show that oxygen began appearing in the atmosphere.

Volcanism also plays a vital role in the atmospheres of other planets. Mercury’s thin exosphere of hydrogen, helium, oxygen, sodium, calcium, potassium and water vapor is due in part of volcanism, which periodically replenishes it. Venus’ incredibly dense atmosphere is also believed to be periodically replenished by volcanoes on its surface.

And Io, Jupiter’s volcanically active moon, has an extremely tenuous atmosphere of sulfur dioxide (SO²), sulfur monoxide (SO), sodium chloride (NaCl), sulfur monoxide (SO), atomic sulfur (S) and oxygen (O). All of these gases are provided and replenished by the many hundreds of volcanoes situated across the moon’s surface.

As you can see, volcanoes are actually a pretty creative force when all is said and done. In fact, us terrestrial organisms depend on them for everything from the air we breathe, to the rich soil that produces our food, to the geological activity that gives rise to terrestrial renewal and biological diversity.

We have written many articles about volcanoes for Universe Today. Here’s an article about extinct volcanoes, and here’s an article about active volcanoes. Here’s an article about volcanoes.

Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.

Astronomy Cast also has relevant episodes on the subject Earth, as part of our tour through the Solar System – Episode 51: Earth.

 

10 Interesting Facts About Volcanoes

Want some volcano facts? Here are 10 interesting facts about volcanoes. Some of these facts you’ll know, and others may surprise you. Whatever the case, volcanoes are amazing features of nature that demand our respect.

1. There are Three Major Kinds of Volcanoes:

Although volcanoes are all made from hot magma reaching the surface of the Earth and erupting, there are different kinds. Shield volcanoes have lava flows with low viscosity that flow dozens of kilometers; this makes them very wide with smoothly sloping flanks.

Stratovolcanoes are made up of different kinds of lava, and eruptions of ash and rock and grow to enormous heights. Cinder cone volcanoes are usually smaller, and come from short-lived eruptions that only make a cone about 400 meters high.

2. Volcanoes Erupt Because of Escaping Magma:

About 30 km beneath your feet is the Earth’s mantle. It’s a region of superhot rock that extends down to the Earth’s core. This region is so hot that molten rock can squeeze out and form giant bubbles of liquid rock called magma chambers. This magma is lighter than the surrounding rock, so it rises up, finding cracks and weakness in the Earth’s crust.

Lava fountain in Hawaii.
Lava fountain in Hawaii. Image Credit: Jim D. Griggs/HVO/USGS

When it finally reaches the surface, it erupts out of the ground as lava, ash, volcanic gasses and rock. It’s called magma when it’s under the ground, and lava when it erupts onto the surface.

3. Volcanoes can be Active, Dormant or Extinct:

An active volcano is one that has had an eruption in historical times (in the last few thousand years). A dormant volcano is one that has erupted in historical times and has the potential to erupt again, it just hasn’t erupted recently. An extinct volcano is one that scientists think probably won’t erupt again. Here’s more information on the active volcanoes in the world.

4. Volcanoes can Grow Quickly:

Although some volcanoes can take thousands of years to form, others can grow overnight. For example, the cinder cone volcano Paricutin appeared in a Mexican cornfield on February 20, 1943. Within a week it was 5 stories tall, and by the end of a year it had grown to more than 336 meters tall. It ended its grown in 1952, at a height of 424 meters. By geology standards, that’s pretty quick.

Detailed View of Ash Plume at Eyjafjallajökull Volcano
Detailed view from space of the ash plume caused by the Eyjafjallajökull volcano in 2010. Credit: NASA

5. There are 20 Volcanoes Erupting Right Now:

Somewhere, around the world, there are likely about 20 active volcanoes erupting as you’re reading this. Some are experiencing new activity, others are ongoing. Between 50-70 volcanoes erupted last year, and 160 were active in the last decade. Geologists estimate that 1,300 erupted in the last 10,000 years.

Three quarters of all eruptions happen underneath the ocean, and most are actively erupting and no geologist knows about it at all. One of the reasons is that volcanoes occur at the mid ocean ridges, where the ocean’s plates are spreading apart. If you add the underwater volcanoes, you get an estimate that there are a total of about 6,000 volcanoes that have erupted in the last 10,000 years.

6. Volcanoes are Dangerous:

But then you knew that. Some of the most deadly volcanoes include Krakatoa, which erupted in 1883, releasing a tsunami that killed 36,000 people. When Vesuvius exploded in AD 79, it buried the towns of Pompeii and Herculaneum, killing 16,000 people.

Image of Mt. Vesuvius, captured in 2000 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). Credit: NASA/EO
Image of Mt. Vesuvius, captured in 2000 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard the Terra satellite. Credit: NASA/EO

Mount Pelee, on the island of Martinique destroyed a town with 30,000 people in 1902. The most dangerous aspect of volcanoes are the deadly pyroclastic flows that blast down the side of a volcano during an eruption. These contain ash, rock and water moving hundreds of kilometers an hour, and hotter than 1,000 degrees C.

7. Supervolcanoes are Really Dangerous:

Geologists measure volcano eruptions using the Volcano Explosivity Index, which measures the amount of material released. A “small” eruption like Mount St. Helens was a 5 out of 8, releasing a cubic kilometer of material. The largest explosion on record was Toba, thought to have erupted 73,000 years ago.

It released more than 1,000 cubic kilometers of material, and created a caldera 100 km long and 30 kilometers wide. The explosion plunged the world into a world wide ice age. Toba was considered an 8 on the VEI.

8. The Tallest Volcano in the Solar System isn’t on Earth:

That’s right, the tallest volcano in the Solar System isn’t on Earth at all, but on Mars. Olympus Mons, on Mars, is a giant shield volcano that rises to an elevation of 27 km, and it measures 550 km across. Scientists think that Olympus Mons was able to get so large because there aren’t any plate tectonics on Mars. A single hotspot was able to bubble away for billions of years, building the volcano up bigger and bigger.

Mauna Kea
Mauna Kea observed from space. Credit: NASA/EO

9. The Tallest and Biggest Volcanoes on Earth are side by side:

The tallest volcano on Earth is Hawaii’s Mauna Kea, with an elevation of 4,207 meters. It’s only a little bigger than the largest volcano on Earth, Mauna Loa with an elevation of only 4,169 meters. Both are shield volcanoes that rise up from the bottom of the ocean. If you could measure Mauna Kea from the base of the ocean to its peak, you’d get a true height of 10,203 meters (and that’s bigger than Mount Everest).

10. The Most Distant Point from the Center of the Earth is a Volcano:

You might think that the peak of Mount Everest is the most distant point from the center of the Earth, but that’s not true. Instead, it’s the volcano Chimborazo in Ecuador. That’s because the Earth is spinning in space and is flattened out. Points at the equator are further from the center of the Earth than the poles. And Chimborazo is very close to the Earth’s equator.

We have written many articles about volcanoes for Universe Today. Here’s an article that tackles about the 10 facts about earth’s core. You might also want to read on the 10 facts about earth. And here’s more: all about volcanoes.

Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.

We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.

Reference:
USGS Volcano Hazards Program

Pompeii Eruption

Pompeii Eruption

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Imagine if you will that it’s bright sunny day in summer. The festival of Vulcanalia, dedicated to the Roman God of Fire, has just passed. Now you’re out looking for some produce to stock up for the coming winter. You’ve just finished a tour of the marketplace and are on your way home when suddenly, the mountain that your town sits at the foot of inexplicably erupts! Fire and ash rain down upon your city, people are baked alive and the town is encased in soot and dirt several meters thick. But, silver lining here, your bodies are so well preserved that when you’re dug up two thousand years later, they’ll have a pretty good idea what life was like at the time of your death. Yes, that’s how the Pompeii Eruption took place. The year was 79 CE; the place, a prosperous town named Pompeii located in the Bay of Naples. It was one of the most significant natural disasters of the ancient world, a major archaeological find in the 18th century, and is now one of the biggest tourist draws in all of Italy.

Based on the letters of Pliny the Younger, historians now believe the eruption to have taken place between the 24th of August and November 23rd, in the year 79 CE. Witnessing the eruption from across the Bay of Naples, Pliny gave a fist-hand account of the destruction. Although it was generally assumed that the people of Pompeii died as a result of suffocation from volcanic ash, a recent multidisciplinary volcanological and bio-anthropological study, merged with numerical simulations and experiments, indicated that heat was the main cause of death. The results of this study show that temperatures would have reached 250 °C up to a distance of 10 kilometers, which would have been sufficient to cause instant death, even if people were sheltered within buildings. The people and buildings of Pompeii were covered in up to twelve different layers of soil which was 25 meters deep and were therefore not discovered for almost two thousand years.

However, rediscovery of the lost city started in 1738, beginning with Pompeii’s sister town of Herculaneum which had also been destroyed in the eruption. At the time, the discovery was the accidental result of workmen digging so that they could build the foundations of a new summer palace for the king of Naples. The discovery of ancient buildings, left largely intact, led to a subsequent intentional excavation of Pompeii itself in 1764 by Francisco la Vega. In addition to intact buildings, many of which contained perfectly preserved Roman frescos, human remains were also uncovered.

For over 20 years now, Pompeii has been one of the most popular tourist destinations in Italy, attracting almost 2.6 million visitors in 2008 alone. In 1997, it was designated a World Heritage Site by UNESCO and attempts are underway to ensure that it can be preserved for future generations. Though the life-blood of the local economy, the pressure exerted by millions of tourists annually is taking its toll on this once-perfectly preserved site.

We have written many articles about Pompeii Eruption for Universe Today. Here’s an article about Mt. Vesuvius, and here are interesting facts about volcanoes.

If you’d like more info on volcanoes, check out the U.S. Geological Survey Homepage. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded related episodes of Astronomy Cast about Volcanoes. Listen here, Episode 141: Volcanoes, Hot and Cold.

Sources:
http://en.wikipedia.org/wiki/Pompeii#Vesuvius_eruption
http://en.wikipedia.org/wiki/Mount_Vesuvius
http://touritaly.org/pompeii/pompeii-main.htm
http://wikitravel.org/en/Pompeii