Fire and Ice - the Volcanoes of Iceland Quiz

Answer: Both of these

Most of the world's volcanoes are found along ocean ridges where tectonic plates are separating, or where tectonic plates are colliding. Relatively few are found at hotspots, where plumes of molten rock rise from the mantle - which can be anywhere, even in the middle of a tectonic plate, like Hawaii. Iceland is on the mid-Atlantic ridge, and thought to be on a hotspot as well, which explains why this is one of the most volcanically active places on Earth.

Answer: Tornadoes

The word "geyser" for a spouting hot spring comes from Geysir, an actual geyser in Haukadalur, Iceland, sometimes called the Great Geysir. This was the first geyser known to Europeans and the first to be described in written records, as early as 1294.

The name Geysir comes from the Icelandic "Geysa" - "to gush". Earthquakes are frequently associated with volcanoes, often as an indicator that an eruption is imminent. Iceland has numerous hot springs, including Deildartunguhver, which emerges at 97 °C with a flow rate of 180 liters/second, making it the most effusive hot spring in Europe. Tornadoes, however, are not related to volcanic activity.

Answer: An outburst flood from a sub-glacial lake

The word "jökulhlaup" is Icelandic in origin, and means "glacier run". It was originally used to refer to the frequent outburst flows from Iceland's largest glacier, Vatnajökull, mostly triggered by geothermal activity, but on occasion by volcanoes like Grímsvötn, which erupted in 1996. What happens is that the geothermal heat from the volcano melts the glacier from underneath, eventually causing the ice to break, releasing a great deal of water in a very short time.

These outburst flows can be tremendously destructive and cause massive flooding.

The 2010 eruptions of Eyjafjallajökull were also accompanied by jökulhlaup.

Answer: It has a flat top and steep sides

A tuya looks a bit like an inverted cupcake, and is formed when lava erupts through an ice sheet or glacier. The name actually comes from Tuya Butte, in the far north of British Colombia in Canada, where a number of tuyas were formed as volcanoes broke through the ice sheet that covered North America during the Pleistocene.

Herðubreið and Hlöðufell in Iceland are tuyas that also formed during the Pleistocene, erupting under the thick ice.

Answer: 18

There are over 130 volcanic mountains on Iceland, 18 of which have erupted since the island was first settled - some of them as many as twenty times - to 2010. It is thought that Icelandic volcanoes have produced a third of the world's total lava output over the last 500 years.

Answer: Hekla

Hekla is actually the most volcanically active part of a ridge 40km long, a series of craters and cones in the shape of an upturned boat stretching for some 5.5km. It was a major eruption of Hekla in 1104, covering half of Iceland with tephra, that made Hekla famous across medieval Europe.

There is evidence of even more massive eruptions in prehistoric times. Hekla is now considered Iceland's most active volcano, erupting two or three times a century. During the 1947-48 eruption event, which lasted over a year, ash was propelled high into the atmosphere, falling as far away as Russia!

Answer: Sulphur dioxide and hydrogen fluoride

Sulphur dioxide is the main gas causing that acrid odour noticed around geothermal areas. Laki erupted for eight months, generating more lava than any other Icelandic eruption in the last 500 years. The toxic gases from Laki killed half of Iceland's livestock, leading to the deaths of a quarter of the inhabitants.

The clouds of sulphur dioxide and ash rolled across Europe as a thick and deadly haze, killing thousands of people and animals. It entered the upper atmosphere of the Northern Hemisphere, resulting in freak weather conditions.

There was a severe winter across North America, causing the Mississippi to freeze over at New Orleans! There was crop failure and famine to Japan, drought in India, and famine in Egypt. It became arguably the deadliest volcanic eruption in historic times, resulting in the deaths of over two million people around the world.

Answer: Katla

Katla has normally erupted every forty to eighty years - and there is a pattern where Katla regularly erupted after an eruption of the Eyjafjallajökull. That said, there were minor eruptions in 1955 and 1999 that didn't breach the ice filling the caldera, but might have released some of the pressure. Katla has erupted sixteen times since the settlement of Iceland to 2010, producing massive basaltic floods in 934 (up to 18 km³ of lava) and majorly destructive glacier runs. Furthermore, it is believed that a prehistoric eruption of Katla produced the Vedda Ash - a layer of tephra found as far away as Scotland, Norway and North America!

Answer: Surtsey

The eruption went on for four years, to the fascination of the world's vulcanologists. Lava flows built up the island to 174m above sea level. It was named for Surtr, the giant with the flaming sword who will battle Freyr at the end of time. Surtsey is now a World Heritage Site, studied by biologists watching the colonisation of the island by plant life.

Answer: Sprayed the lava flows with cold sea water

The eruption began almost without warning. A fissure opened, lengthening to cross the small island, as lava began to fountain from it, together with volcanic ash and tephra, building a cone 100m high in less than two days. The island was evacuated, and soon homes were buried in ash.

The important thing for residents was to save as much as they could, as the fire fountains gave way to a slow-moving mass of lava that threatened to bury both town and harbour. First, citizens sprayed cold seawater onto the lava from a dredging ship offshore, and then they bravely used bulldozers to lay pipes across the top of the flow to spread more cold seawater across the lava.

The cold water solidified the lava, stopping the flow, and after the eruption ended, the inhabitants were able to rebuild and return to their island.