Hundreds of people trekked over a dark, rocky landscape in Iceland. The sharp smell of burning rock filled their noses. With each step, the air grew hotter. Finally, they reached their destination: a flowing river of lava!

In March 2021, a volcano called Fagradalsfjall (fah-grah-dahls-fyaht-el) began erupting for the first time in about 6,000 years. The melted rock flowed down the mountain’s sides and oozed from cracks in the ground. As it cooled, it hardened to form new layers of jagged, black land.

All volcanic eruptions can be dangerous. Luckily, this one wasn’t a big threat to nearby residents. It wasn’t explosive, and no one lived in the lava’s path. In fact, crowds gathered to watch the spectacular scene. Some people even cooked hot dogs over the cooling lava!

Volcano scientists called volcanologists headed to the volcano too. They wanted to collect samples of the gooey lava. By studying the samples, scientists can better understand how the volcano works. “It’s like opening a window into parts of the planet we never get to see,” says volcanologist Edward Marshall.

Hundreds of people hiked over a dark, rocky landscape in Iceland. A sharp smell filled their noses. It was the smell of burning rock. With each step, the air changed. It grew hotter. Finally, they reached their destination: a flowing river of lava!

In March 2021, a volcano called Fagradalsfjall (fah-grah-dahls-fyaht-el) began erupting. It was the volcano’s first eruption in about 6,000 years. The molten rock flowed down the mountain. It also oozed from cracks in the ground. The molten rock cooled and hardened. This formed new layers of jagged, black land.

All volcanic eruptions can be dangerous. Luckily, this one wasn’t a big threat to nearby residents. It wasn’t explosive. And no one lived in the lava’s path. In fact, crowds gathered to watch the scene. Some people even cooked hot dogs over the cooling lava!

Scientists who study volcanoes are called volcanologists. They headed to the volcano too. They wanted to collect samples of the gooey lava. Studying the samples helps scientists understand how the volcano works. “It’s like opening a window into parts of the planet we never get to see,” says volcanologist Edward Marshall. 

The island of Iceland is only about the size of Kentucky. But it’s home to more than 30 active volcanoes. The reason there are so many volcanoes is that Iceland sits on the Mid-Atlantic Ridge. That’s one of the borders between giant slabs of rock called tectonic plates. At the Mid-Atlantic Ridge, plates pull apart about 1 inch (3 centimeters) per year. Magma, melted rock underground, seeps through the cracks and bursts to the surface as lava.

Fagradalsfjall is a shield volcano. This type of volcano doesn’t usually have violent eruptions. But some volcanic eruptions do major damage to surrounding areas. The more scientists know about a volcano, the better they can detect signs an eruption might be coming. They use data to build digital models of volcanoes. These computer programs show how volcanoes work.

Weeks before the 2021 eruption, scientists detected 50,000 earthquakes in the area—far more than normal. That was one of many signs that the volcano was about to erupt!

Iceland is an island. It’s only about the size of Kentucky. But it has more than 30 active volcanoes. There are so many volcanoes because Iceland sits on the Mid-Atlantic Ridge. That’s a border between giant slabs of rock. These slabs are called tectonic plates. At this border, the plates pull apart. They pull apart about 1 inch (3 centimeters) per year. There is melted rock underground called magma. It seeps through the cracks. Then it bursts to the surface as lava.

Fagradalsfjall is a shield volcano. This type of volcano doesn’t usually have violent eruptions. But some eruptions damage surrounding areas. Knowing more about a volcano is important. It helps scientists better detect signs of future eruptions. They use data to build digital models of volcanoes. These computer programs show how volcanoes work.

Weeks before the 2021 eruption, scientists noticed something. They detected 50,000 earthquakes in the area. That’s far more than normal. It was one of many signs that the volcano was about to erupt!