Iceland's largest volcano, Katla, is nearly 5,000 feet tall and hasn't had a major eruption since 1918, even though scientists report it usually erupts once every 50 years. But two earthquakes underneath the massive volcano triggered a recent increase in seismic activity, and experts at the Icelandic Meteorological Office say they can't rule out the possibility of an eruption.
In 2014, a remote Icelandic volcano called Bárðarbunga began experiencing an intense, high-frequency earthquake swarm — a series of seismic events occurring in a short period of time that typically precede volcanic eruptions. The small island nation also made headlines during the 2011 eruption of Grímsvötn, which was the largest eruption the country had witnessed in more than 50 years. The ash that spewed from Grímsvötn eventually made its way into the atmosphere, disrupting air travel for several days.
Grímsvötn and Bárðarbunga are part of the same volcanic system that was responsible for the most catastrophic volcanic event in Iceland's history: The 1783-1784 eruption of the Laki volcanic fissure (seen above). The resulting clouds of poisonous gas killed over 50 percent of the country's livestock, which in turn sparked a famine that killed 25 percent of Iceland's human population.
The Laki eruption affected more than just Iceland, though. As poisonous clouds of sulfur dioxide gas drifted into the atmosphere, global temperatures dropped, throwing human agriculture out of whack. Crops in Europe began to fail, and even regions as far south as India suffered debilitating droughts. It's estimated that a staggering 6 million people across the globe were killed by Laki, making it the deadliest volcanic eruption in recorded history.
So how worried should Icelandic residents and air travelers be about an impending explosion? Well, Bárðarbunga holds the distinguished honor of erupting "more lava than any other volcano on the planet in the last 10,000 years," but luckily, most eruptions in the past several centuries have been relatively small. It's difficult to get a complete picture since much of the volcano sits below the thick ice of the Vatnajökull glacier, making it more difficult to study than other volcanoes.
If Bárðarbunga or Katla does erupt, it's impossible to know how it will develop, but politicians and scientists are taking the necessary precautions necessary to prepare the country for the best- and worst-case scenarios.
While Icelanders play the waiting game, here's a brief visual tour of some of the country's most beautiful volcanic and geothermal creations. Turbulent geysers, ancient mountains, steaming fumaroles, craggy volcanic slopes, serene crater lakes, bubbling mudpots — they're all awe-inspiring reminders of how beautiful yet dangerous our ever-changing planet can be.
These steaming geothermal currents are found in Kerlingarfjöll, a mountain range located in the central highlands of Iceland.
A brilliant blue pool known as Bláhver is found in the geothermal fields of Hveravellir in Iceland's highlands.
Öskjuvatn, a green crater lake found within Askja's Víti crater, was formed after an eruption in 1875.
Kirkjufell, which means "Church Mountain" in Icelandic, lies on the north coast of the Snæfellsnes peninsula.
Found in a geothermal area next to the Hvita River, the Strokkur geyser erupts every four to eight minutes.
Krýsuvík is a geothermal area on the Reykjanes peninsula that boasts hot springs, fumaroles and mud pots.
Kirkjufell is a great place to capture photos of the aurora borealis.
The Fjallabak Nature Reserve features a collection of screes of volcanic rock and geothermal attractions.
The vibrant colors found on the slopes of Brennisteinsalda volcano are attributed to sulfur spots, live mosses, volcanic ashes and iron deposits.
A blue-colored fumarole steams at a geothermal area near the Krafla caldera in the Mývatn region.
Situated at the edge of a lava field, the surreal landscapes of Landmannalaugar are found in the Fjallaback Nature Reserve.
Ófærufoss is a picturesque waterfall perched on the chasm of the Eldgjá volcano.
A small footbridge helps tourists traverse the geothermal area of Námafjall in northern Iceland.
Lake Mývatn stretches out in front of the Krafla caldera.
The 1973 eruption of Eldfell volcano on the Icelandic island of Heimaey came without warning, and caused a major crisis for the country.
Editor's note: This story has been updated since it was originally published in August 2014.