Why is it in the News?

• Mount Etna, Europe's tallest and most active volcano, erupted again on the island of Sicily on Sunday, November 12, 2023.
• The eruption sent a lava fountain into the air and ash miles into the sky.
• The ash fell on the nearby city of Catania, causing some disruption to air travel.

About Mount Etna:

• Mount Etna is a large stratovolcano on the eastern coast of Sicily, Italy.
• It is the highest and most active volcano in Europe, and one of the most active in the world.
• Its recorded volcanic activity dates back to 1500 B.C. Since then, it has erupted more than 200 times.
• Mount Etna is a complex volcanic system, made up of several different lava domes and craters.
• The summit crater, known as the Voragine, is a large depression that is often filled with lava.
• The volcano also has several calderas, which are large, sunken depressions that are formed by the collapse of the volcano's summit.
• In recent years, Mount Etna has become increasingly active, with several eruptions in the past decade. The most recent eruption began in 2022 and has produced a number of lava flows and ash clouds.
• The eruption has also caused a number of earthquakes, some of which have been felt in nearby towns and cities.

Other volcanoes erupt for much longer than Etna:

• One of the most famous long-term eruptions was the Kilauea volcano in Hawaii.
• Its spewing spree in 1983 continued — almost nonstop — for 35 years until 2018, only to start again in 2021. The eruption is still ongoing.
• Dukono in Indonesia started erupting in August 1933 and is still continuing.
• Santa Maria in Guatemala began erupting in June 1922 and continues to this day.
• Yasur in Vanuatu first rumbled to life in about 1270 (± 110 years) and as of June 2023, was still erupting.
• Lava domes: Lava domes are formations created by the slow extrusion of viscous lava, typically rhyolitic or andesitic, forming a steep-sided mound or dome-shaped structure near a volcano's vent.
• Crater: A volcanic crater is a bowl- or funnel-shaped depression that usually lies directly above the vent from which volcanic material is ejected.

What is a volcano?

• Volcanoes are openings, or vents where lava, tephra (small rocks), and steam erupt onto the Earth’s surface.”
• Volcanoes can be on land and in the ocean.
• They are, in part, a result of their own eruptions but also the general formation of our planet, as tectonic plates move.
• Mountain ranges like the Andes in South America and the Rockies in North America, as well as volcanoes, formed through the movement and collision of tectonic plates.
• How do volcanoes erupt?
• Essentially, it’s a case of magma, or molten rock, below the surface of the Earth, bubbling up, rising, and overflowing, like boiling milk out of a pot on a stove.
• The magma finds its way to vents in the volcano and gets spewed across the land and into the atmosphere.
• When magma erupts from a volcano, it is called lava.
• There are four main types of volcanoes:
• Cinder cones
• Composite or stratovolcanoes
• Shield volcanoes and
• Lava domes
• Their type is determined by how the lava from an eruption flows and how that flow affects the volcano, and, as a result, how it affects its surrounding environment.
• Each volcano is unique and can vary in size and composition, but a crucial aspect of these mountains is the amount of silicon dioxide present in the magma and rocks below the surface.
• A high silica content can lead to violent eruptions that are categorized as explosive.
• Silica makes magma preventing it from readily flowing.
• Eruptions such as Alaska’s Novarupta in 1912 and Washington’s Mount St. Helens in 1980 all were composed of high amounts of silica.
• When silica values are low, eruptions are categorized as effusive with magma that is thinner and tends to be less explosive.

Types of Volcanoes:

• Cinder Cones: Cinder cones are considered to be the most common and simplest type of volcano in the world.
• Their structures are typically small, so their footprint doesn’t cover much terrain.
• Many are considered by volcanologists to be monogenetic and only erupt once during their lifespan.
• Once a cinder cone volcano becomes dormant, it usually never erupts again.
• Composite Volcanoes: Composite volcanoes are some of the largest and the most picturesque of any mountain in the world.
• Eruptions can be explosive and produce devastating impacts.
• Unlike a cinder volcano, composite volcanoes are usually active over a period of thousands of years.
• Mount St. Helens, Krakatoa, Mount Pinatubo, and Hunga-Tonga-Hunga-Ha’apai are all considered to be composite volcanoes, which also can be known as stratovolcanoes.
• The last significant composite volcano eruption was in Tonga in early 2022.
• Shield Volcanoes: This type of volcano is typically the largest on Earth and covers a broad swath of terrain.
• Hawaii’s Mauna Loa and K?lauea are classic examples of shield volcanoes and are among the most active in the world.
• Mauna Loa, from the sea floor base to its top elevation, is more than 33,000 feet tall.
• The great width of these volcanoes is a result of thin lava flows.
• Eruptions are not considered to be eruptive and usually rank low on the VEI.
• Threats from landslides and volcanic smog are usually significant with these types of volcanoes.
• Lava Domes: Lava dome features are usually quite small and due to thick magma, the lava doesn’t have wide impacts.
• These types of volcanoes can be explosive and are frequently found in the craters of composite volcanoes.
• Domes tend to grow from material that builds up over time by hardening lava from eruptions.
• Explosive eruptions can occur with little warning, which makes these features dangerous, if in the immediate area.

Volcanoes that are particularly active in the Pacific Ring of Fire:

• Some of the most active volcanoes are located in the Pacific Ring of Fire, which includes New Zealand, Southeast Asia, Japan, and the western coast of the Americas.
• About 90% of all earthquakes worldwide strike within this region.

Can scientists predict volcanic eruptions?

• Scientists are capable of predicting volcanic eruptions hours, or sometimes several days, in advance.
• This is not the case with earthquakes, which are much harder to predict.
• Scientists use seismographic data from earthquakes and other tremors, because those can be a precursor to volcanic eruptions.
• They monitor the ground for signs of deformation, which may be caused by the movement of magma.
• They also take readings of volcanic gas emissions, and changes in gravity and magnetic fields.