A Close Look at 9 of the World's Most Active Volcanoes

• Volcanoes rank right up there in the world's arsenal of powerful forces. 

• Scientists define an active volcano as one that has erupted in the last 10,000 years. 

• Based on this definition, the earth has around 1,500 active volcanoes spread across the globe.  Around 75 percent of those are located along the pacific ring of fire – a region that spans the perimeters of landmasses on the Pacific ocean.

Why do volcanoes form and erupt?

All volcanoes form through the basic process of magma working its way up through the earth's mantle and crust. As the magma works its way through to the surface, it eventually breaches and starts to harden. This hardening of magma over and over causes the formation of a taller or wider volcano.

The source of this magma comes from deep within the earth. It's so hot near the earth's core that rocks melt and become a thick flowing substance, what we know as magma. As the rocks melt into magma, their density actually changes to become lighter than the solid rocks around them.

This causes the magma underground to rise like bubbles in the water. This magma rises under the earth's harder rock layers, collecting in magma chambers. When the rock strata under the crust of the earth are weaker in certain areas, the magma can heat through these different pathways creating lava tubes and fissures, often all the way up to the surface. 

Where the underground magma breaks through the surface, an eruption occurs. Some eruptions are explosive while others ooze slowly out. This is due to caps being formed over time, where lava seals off a particular magma tube, only for pressure to build up and eventually cause an explosion. 

Determining a top list of most active volcanoes becomes somewhat subjective in certain cases, but thanks to new research, the volcano coming in at the number one spot definitely deserves to be there.

Let's take a look at the world's most active volcanoes and where these volcanoes are located.

1. Mauna Loa - Hawaii

Mauna Loa is the biggest volcano on Earth, a title it held for a long time, briefly lost in 2013, but now has back again. In 2013, scientists announced that they believed the Tamu Massif underwater volcano was the world's largest, but now they don't even think it's a volcano, according to National Geographic. Mauna Loa is thought to have been erupting more or less continuously for 700,000 years now. Due to its frequent lava flows, it poses a great risk to surrounding communities.

2. Eyjafjallajokull - Iceland

Apart from having the most unpronounceable name on this list, Eyjafjallajokull erupted as recently as 2010. While the eruption itself was relatively small, the ash plume from the eruption caused a global air traffic crisis, causing many flights to be diverted or canceled. Due to this relatively recent activity, it's arguably one of the most famous volcanoes today. This particular volcano has an ice cap covering its caldera, a notably different trait compared to the other volcanic mountains on this list. 

3. Mount Vesuvius - Italy

Nearly all active volcanoes around the world can be dangerous if you're located near them during an eruption, but in many cases, our focus on one volcano, in particular, tends to be due to its geographic vicinity to a population center. Mount Vesuvius is located just 5,5 miles (9 km) from the city of Naples, Italy. This closeness means that this is the most densely populated region with an active volcano anywhere in the world.

The catastrophic eruption in 79 AD buried the cities of Pompeii and Herculaneum under ash and lava. Vesuvius is the only volcano on the European mainland to have erupted within the last hundred years. Today, it is regarded as one of the most dangerous volcanoes in the world, because of its proximity to Naples and its tendency towards violent, explosive eruptions.

4. Mount Nyiragongo - Congo

Mount Nyiragongo has one of the largest lava lakes of modern times inside its main crater. Located in the Virunga National Park in the Democratic Republic of the Congo, it's responsible for roughly 40 percent of historical eruptions in Africa. Since 1882, the volcano has erupted at least 32 times and its lava lake consistently shows fluctuation in levels, indicating underground magma activity.

On 10 January 1977, the crater walls fractured, and the entire lava lake emptied in less than an hour, flowing down the sides of the volcano at speeds of up to 37 mph (60 kph), overwhelming villages on the upper slopes, and killing at least 70 people. 

Lava lakes reformed in the crater following eruptions in 1982–1984, and the volcano erupted again in January 2002, when lava reached the outskirts of the provincial capital of Goma. A continued outpouring of gases has killed people since then and a rise in the lava lake in 2020 has led researchers to suggest that the volcano may erupt again by 2024. 

5. Taal Volcano - Philippines

Located 30 miles (48 km) south of the capital city of Manila, Taal volcano is the second most active in the Philippines. However, this volcano is notable due to its fatality rate over the years, with around 6000 people having been killed. Due to its proximity to dense population centers, the volcano remains a risk. 

Now, the volcano had been fairly quiet since 1977, but erupted again in January 2020, spewing ashes as far as Metro Manila, and parts of Central Luzon. Ashfalls and volcanic thunderstorms forced evacuations and these were followed by magma eruptions with a lava fountain accompanied by thunder and lightning. A total of 39 people died in the eruption, from either refusing to evacuate or from health-related problems during the evacuation.

6. Mount Merapi - Indonesia

Mount Merapi is thought to have produced more lava flow than any other volcano anywhere in the world. In October 2010, a high alert was raised for people living in the surrounding areas, who were warned to evacuate.

On the 25th of October lava began to erupt from its southern slopes. The eruptions continued throughout November, eventually causing the deaths of around 350 people and leaving many in the surrounding population homeless. It is known as the most active volcano in all of Indonesia, erupting as recently as 2018, and causing frequent evacuations in the region.

7. Galeras - Colombia

Galeras's summit rises an impressive 2,65 miles (4,276 meters) above sea level and has been quite active for millions of years. It is thought that Galeras has been an active volcano for around a million years, but the first recorded eruption was in 1535. An eruption over 500,000 years ago actually expelled 15 cubic kilometers of material into the surrounding landscape and formed a caldera. The volcano lies near the city of Pasto and poses a threat. 

Notably, in 1978, scientists thought this volcano had gone dormant, but just 10 years later it erupted. After that, in 1993, it erupted during a Decade Volcano conference in Pasto, killing 6 scientists who had mounted an impromptu expedition to the crater, along with three tourists. Activity in recent times continues at a low level, dusting local areas in ash and presenting a risk to the nearby residents.

8. Sakurajima - Japan

Sakurajima used to be its own island volcano before its lava flows grew large enough to connect the mass to the Osumi Peninsula in Japan. This volcano has been erupting almost constantly since 1955, and thousands of small explosions happen each year, creating hazardous conditions for the nearby city of Kagoshima.

On 18 August 2013, the volcano erupted from the Showa crater and produced an ash plume 3 miles (5,000 meters) high. It was the 500th eruption of the year.

Notably, Sakurajima erupted in 1914, after being dormant for over a century. Luckily for the residents at the time, large earthquakes in the days prior gave them enough warning to flee to safety before the eruption hit. Once it did, it generated the massive lava flows that are responsible for connecting the island to the mainland.

In fact, the 1914 eruption was atypical for the volcano, trending away from being explosive and tending to produce massive lava flows that continued on for months. During the flow of lava, several other smaller islands were engulfed.

9. Santa Maria - Guatemala

The Santa Maria volcano is located in the western highlands of Guatemala, near the city of Quetzaltenango. Its crater was formed during an explosion in 1902, which ranks as one of the three largest eruptions in the 20th century, and one of the 5 largest eruptions in the last several hundred years.

This volcano sits along the fault line of the Cocos plate and the Caribbean plate; the movement of which is usually the cause of these volcanic eruptions. The last eruption occurred in March of 2011 and lava flows have remained fairly constant since then. 

In conclusion, the world's most active volcanoes are remarkable natural phenomena that have caused widespread damage to human life. While they may pose significant risks to nearby populations, these volcanoes also provide fertile ground for new life and serve as a reminder of the Earth's incredible power and resilience.