Volcanology is cool

Volcanoes are very, very, very hot, but volcanology is cool! And this is a great time to delve into a little volcanology because some fiery drama is threatening to unfold in Iceland sometime soon.

I think many people - including myself - were unaware that Iceland even has volcanoes until the eruption of Eyjafjallajökull in 2010. That eruption was big international news because it was an explosive one, sending a huge plume of ash into European airspace. Over 100,000 flights were canceled, affecting 10 million passengers. Businesses that rely on air shipping were stymied. It is estimated that the European economy lost $5 billion (yes, with a "b") due to Eyjafjallajökull. That got people to pay attention to Iceland's volcanoes!


Eyjafjallajökull looking very innocent in 2012. Its peak is 5,400 feet above sea level, and its ice cap is 650 feet thick in places.

Eyjafjallajökull looking very innocent in 2012. Its peak is 5,400 feet above sea level, and its ice cap is 650 feet thick in places.

Fjallsjökull glacier, descending from Iceland's largest ice cap, Vatnajökull.

Fjallsjökull glacier, descending from Iceland's largest ice cap, Vatnajökull.

Iceland is often called the Land of Fire and Ice because much of its natural splendor has been shaped by volcanic activity, and of course, it has about 300 beautiful glaciers. (As an aside, Iceland is also the land of unpronounceable names, so if you are reading this out loud to a friend, good luck with that!)


An amazing display of the icy side of Iceland's split personality: Jökulsárlón, a beautiful glacial lake where large chunks of ice have broken off the end of Breiðamerkurjökull glacier (an outlet glacier of Vatnajökull).

An amazing display of the icy side of Iceland's split personality: Jökulsárlón, a beautiful glacial lake where large chunks of ice have broken off the end of Breiðamerkurjökull glacier (an outlet glacier of Vatnajökull).

Volcanologists love Iceland. With 33 active volcanoes and over a hundred dormant ones, the island is like a laboratory for volcanic study. Icelandic volcanoes have a nice diversity of eruptive styles and magma types. That's a lot of volcanic goodness packed onto one relatively small island.


Volcanic history

Iceland was first settled in 874 CE, and there have been about 200 volcanic eruptions since then. On average, there is a volcanic eruption in Iceland every 4-5 years, but you certainly can't hold volcanoes to any kind of schedule. Most of the eruptions happen without too much impact. However, some of the eruptions have been devastating. The Laki eruption in 1783-84 killed about 10,000 people - nearly a quarter of Iceland's population at that time - when volcanic gases caused a famine by affecting crops, sheep and fish. Eyjafjallajökull was a relatively small eruption, and even that was enough to create a mess that spread far beyond Iceland.


Skaftáreldahraun lava field, covered in colorful moss. The lava was deposited here during the devastating Laki eruption.

Skaftáreldahraun lava field, covered in colorful moss. The lava was deposited here during the devastating Laki eruption.

I traveled to Iceland with my husband, brother and sister-in-law in 2012 - two years after Eyjafjallajökull erupted. We soon came to realize that signs of Iceland's volcanic nature were all around us - not just volcanoes, but also beautiful lava formations and mysterious geologic features that steamed, bubbled or boiled.


Lava formations in Lake Mývatn. This lake was created about 2,300 years ago during a volcanic eruption.

Lava formations in Lake Mývatn. This lake was created about 2,300 years ago during a volcanic eruption.

Black volcanic sand makes Iceland's beaches spectacular.

Black volcanic sand makes Iceland's beaches spectacular.

This volcanic activity makes Iceland an incredibly beautiful place, and it also enables them to use renewable geothermal and hydropower resources to generate all of their electricity. The hot baths are pretty nice, too! On the downside, volcanic activity can be unpredictable and very destructive. And in Iceland, it's not a matter of if - it's when.


Mývatn Nature Bath, geothermally heated by nature, is a great place to relax while anticipating the next volcanic eruption.

Mývatn Nature Bath, geothermally heated by nature, is a great place to relax while anticipating the next volcanic eruption.

Why is Iceland so volcanic?

For one thing, plate tectonics! You probably remember from your high school geology class that giant plates of the Earth's crust essentially slide around on the more fluid layers of Earth below it. Iceland sits right on the Mid-Atlantic Ridge, where the North American and Eurasian plates are pulling apart from each other at a rate of almost an inch per year. Geologically speaking, that's pretty fast. This divergence tears open the Earth's crust and allows magma (molten rock below the Earth's surface) to rise to the surface in a volcanic eruption. You can actually see the divergence in action in Þingvellir.


This valley at Þingvellir National Park is widening a little bit each year as the North American and Eurasian plates pull apart from each other.

This valley at Þingvellir National Park is widening a little bit each year as the North American and Eurasian plates pull apart from each other.

The other thing that makes Iceland so volcanic is that it sits over a "hot spot." That's not something you would expect of a place with "ice" in its name. There are several interesting theories as to what causes this, but whatever the cause, volcanologists agree there is increased melting of rock in the Earth's mantle below Iceland. Diverging plates and a hot spot add up to lots of volcanic activity, and explain why Iceland is the only place along the entire Mid-Atlantic Ridge that's not underwater.


This geyser, named Strokkur, erupts every 5-10 minutes, shooting hot water and steam as much as 130 feet in the air. Nearby is a geyser named Geysir. It is the largest in the world, but erupts very infrequently. Its name became the generic term for all such geologic phenomena. Geysers are rare. They require lots of water, a special plumbing system, and plenty of heat from magma beneath the Earth's surface.

This geyser, named Strokkur, erupts every 5-10 minutes, shooting hot water and steam as much as 130 feet in the air. Nearby is a geyser named Geysir. It is the largest in the world, but erupts very infrequently. Its name became the generic term for all such geologic phenomena. Geysers are rare. They require lots of water, a special plumbing system, and plenty of heat from magma beneath the Earth's surface.

Fumaroles at the Hverir geothermic field. Fumaroles are small vents in the ground through which volcanically heated steam escapes. Sometimes a little sulfur dioxide or hydrogen sulfide gas escapes, too, giving the area a nice rotten egg smell.

Fumaroles at the Hverir geothermic field. Fumaroles are small vents in the ground through which volcanically heated steam escapes. Sometimes a little sulfur dioxide or hydrogen sulfide gas escapes, too, giving the area a nice rotten egg smell.

Mud pot at the Hverir geothermic field. This is basically a hot spring with lots of thick, gooey mud in it. Boiling mud! How awesome is that?

Mud pot at the Hverir geothermic field. This is basically a hot spring with lots of thick, gooey mud in it. Boiling mud! How awesome is that?

What happens when a volcano erupts?

Magma collects in magma chambers 1-6 miles below the surface of the Earth. Volcanic eruptions occur when the pressure in the chamber builds to the point where the magma has to go somewhere - usually upward and out through some kind of a vent. This could be a central summit vent in the center of a volcanic cone (what we typically picture), or a fissure in the ground that's many miles long. Volcanic eruptions fall broadly into two main categories. In effusive eruptions, lava flows from the volcano, often creating lava fountains and rivers of hot, molten rock. In explosive eruptions, rock and magma is forcefully ejected, usually along with some nasty gases and a lot of ash. Needless to say, these are the most dangerous eruptions.

Explosive eruptions are especially likely to occur where hot magma comes in contact with water. Because many of Iceland's volcanoes are covered by ice caps, their volcanoes can get pretty feisty. In addition to the usual volcanic hazards such as lava flows, ashfall, poisonous gases, earthquakes and volcanic lightning, they have to worry about flooding. Really serious flooding. Volcanoes that erupt beneath a glacier cause ice to melt, creating a huge lake under the glacier that's held back by a dam of rock or ice. If the dam gives way, or the collecting water floats the glacier upward, all of that water can be released in one sudden, catastrophic flow. That is called a jökulhlaup - an Icelandic term that has made its way into everyday vocabulary for volcanologists. A jökulhlaup can destroy any vegetation, roads, bridges and buildings in its path.


Skeiðarársandur, the world's largest outwash plain, created as meltwater from glaciers made its way to the sea, depositing lots of black lava sand and ashes. Jökulhlaups caused by Grímsvötn rush across this plain.

Skeiðarársandur, the world's largest outwash plain, created as meltwater from glaciers made its way to the sea, depositing lots of black lava sand and ashes. Jökulhlaups caused by Grímsvötn rush across this plain.

Pseudocraters look like mini-volcanoes - but they aren't. They are created when hot lava oozes across a swamp or lake. Steam explodes up through the lava, breaking the lava up into fragments and forming cones around the vents.

Pseudocraters look like mini-volcanoes - but they aren't. They are created when hot lava oozes across a swamp or lake. Steam explodes up through the lava, breaking the lava up into fragments and forming cones around the vents.

Predicting volcanic eruptions

When it comes to predicting volcanic activity, volcanologists are stuck between a rock and a hard place. They need to give people enough advance warning of an impending eruption that they can get out of harm's way, but they also don't want to freak people out unnecessarily. In Iceland, this interesting but tricky job falls to the Icelandic Meteorological Office (IMO). They monitor all 33 active volcanoes using 170 instrument stations that send data back to the main IMO office in Reykjavík 24/7. By measuring seismic activity, volcanologists can tell when magma is starting to rise toward the surface. Deformities in the shape of a mountain or higher emissions of carbon dioxide or sulfur dioxide gases can also signal that magma is on the move. Changes in the flow of glacial rivers can indicate an increase in geothermal activity.

Because many volcanoes are being tracked all around the world, volcanologists are getting a better understanding all the time of how changing patterns of activity can signal an eruption. However, predicting eruptions is still not an exact science. Early warning signs can go on for months or years. Further, each volcano has its own personality, and its behavior can change at any time. I would think this could keep volcanologists awake at night.

When scientists at the IMO feel an eruption is imminent (minutes to hours away), they contact local civil defense authorities. Automated phone and text messages are then sent to people in the affected area. Can you imagine getting that text message? OMG! They could be told to evacuate within 30 minutes, or they could be told to leave immediately. Either way, they don't have a lot of time to think about it. Feeling seismic activity beneath their feet probably gives people a sense of urgency.


The town of Vik is in danger of being washed away by a jökulhlaup caused by the eruption of Katla. This town with 300 residents hosts up to 3,000 tourists per day.

The town of Vik is in danger of being washed away by a jökulhlaup caused by the eruption of Katla. This town with 300 residents hosts up to 3,000 tourists per day.

What's going on in Iceland now?

In recent weeks, volcanologists have been detecting signs of increased activity from four of Iceland's volcanoes: Grímsvötn, Bárðarbunga, Katla and Hekla. These precursor signals could go on for days, weeks, months or years. When volcanologists see a very intense cluster of earthquakes, or significant swelling of the volcano, they'll know an eruption is about to happen - and that's when it's time to make that awkward call to the civil defense authorities.


Untitled photo

What will the eruption be like?

Most of the time, Icelandic volcanoes erupt without excess drama. While it's probably pretty exciting for the people who live nearby, the effects are not widespread. However, any one of these volcanoes could create a situation like we saw when Eyjafjallajökull erupted in 2010 - or worse. If they all erupt at the same time...well, we don't really want to dwell on that.

All four of these volcanoes usually produce explosive eruptions that can ebb and flow for months, with the worst of it often happening in the first few days or weeks. They are known to generate a lot of ash, and the ash cloud can cause hours of total darkness in the area around the volcano. It can disrupt ground transportation, cause power outages and loss of radio communication, damage vegetation and cause respiratory distress. If the ash cloud is big enough, and the wind is right, it can disrupt air traffic in Europe and beyond. Volcanic gases can cause widespread air pollution and acid rain. There is also likely to be damage from jökulhlaups.

Once the worst of the eruption ends, the cleanup begins. It's really important to get rid of the ash as soon as possible. Volcanic ash is actually teeny tiny pieces of rock and glass, and is abrasive and corrosive. When wet, ash makes roads slippery and can conduct electricity. It can cause health issues for people and livestock, and can damage crops, cars, buildings, wastewater treatment systems, and more. Oh, and it can basically turn into cement if it gets wet. Yuck. Effective cleanup requires a collective and coordinated community effort.


After the 2010 eruption of Eyjafjallajökull covered the town of Vik in ash, a British newspaper, The Telegraph, interviewed Vik's mayor, Sveinn Palsson. He said, "Volcanoes are just not the sort of thing that panic us. In Florida, they live with hurricanes. In Iceland, we live with volcanoes." Katla is bigger than Eyjafjallajökull, and is even closer to Vik. Let's all keep our fingers crossed that the next eruption in Iceland is relatively tame, that everyone stays safe, and that Vik doesn't wash away in a jökulhlaup.



Cast of Characters

Volcanoes each have their own distinct personality that reveals itself over time. Here's some additional information about each of the Icelandic volcanoes that are threatening to erupt in the near future.


Grímsvötn

• Most active volcano in Iceland, erupting every 10 years, on average.

• Last eruption was in 2011.

• Sits beneath Vatnajökull, Iceland's largest ice cap.

• Notorious for causing jökulhlaups.

• Usually produces small to medium size explosive eruptions, but its larger eruptions have been doozies. The highly destructive Laki eruption, mentioned above, was from one of Grímsvötn's fissures. And, a jökulhlaup caused by a Grímsvötn eruption in 1996 destroyed a bridge on the Ring Road, creating a transportation nightmare.


Bárðarbunga

• 26 eruptions in the last 1,100 years (since Iceland was settled and people were around to witness eruptions).

• Last eruption was in 2014-2015.

• Sits under the Vatnajökull ice cap - fueled by the same source of magma as Grímsvötn

• Mostly produces explosive eruptions, but the last one was more effusive, with lots of lava and very little ash. The last eruption also belched out lots of sulfur dioxide gas, causing pollution problems in Iceland and the UK.


Katla

• 21 eruptions in last 1,100 years.

• Ominously dormant since 1918 - the longest dormant period in its known history.

• Sits beneath the Mýrdalsjökull ice cap, so has the potential to be very explosive and cause jökulhlaups with a flow rate similar to the Amazon River. The town of Vik would be in harm's way as massive quantities of water make their way to the sea. Yikes.

• Its activity seems to be connected to Eyjafjallajökull. When Eyjafjallajökull erupts, Katla tends to erupt several months or years later. It has been 7 years since Eyjafjallajökull erupted, so Katla seems overdue.

• Has not erupted since instrumental monitoring of volcanoes began, so volcanologists don't have a past history of measurements to help with prediction of eruptions.


Hekla

• 23 eruptions in the last 1,100 years, making it the third most active volcano in Iceland.

• Last eruption was in 2000.

• Interval between eruptions varies from 9 to 121 years.

• Does not have an ice cap, so does not produce jökulhlaups. However, it is covered in snow all year long, so floods from melting snow can be expected.

• Its eruptions tend to be a mix of explosive and effusive events, so there can be a lot of ash, as well as lava flows. It can also create a pyroclastic flow, in which a cloud of superheated rock, ash and poisonous gas rush down the side of the volcano at high speeds. This is what killed most of the people in Pompeii when Mount Vesuvius erupted in 79 CE.

• Known to have a short fuse. Eruptions come without much warning!



Click here to sign up for the Nature Notes email newsletter. That way, the next time I post a new blog entry, the content will land conveniently in your inbox.

Powered by SmugMug Owner Log In