How was Iceland formed and why there is volcanic activity in Iceland?
The geographical location of Iceland on the Mid-Atlantic Ridge and above one of the hotspots in Earth’s mantle where the Eurasian and the North American tectonic plates are constantly spreading apart – result in strong volcanism and abundance of volcanic formations.
There is balance in nature and once the crust is melted in one spot on Earth, it has to get out to the surface elsewhere: in form of mountains as a result of tectonic movements or as a new island in the middle of the ocean. This is exactly the process in which Iceland was created when two tectonic plates started to spread out – lava from the mantle plum came out of to the surface and new land started to be built. Iceland is one of youngest lands on Earth and it’s still in a process of forming. As the tectonic plates are continuing to spread several earthquakes and eruptions take place.
Now, In Iceland, the remains of the previous eruptions of now-dormant volcanoes are being turned into touristic attractions that allow people to have a once-in-a-life-time experience to enter to a volcano or to have a walk inside a lava tube.
How lava tubes are created?
Lava caves in a shape of tubes are created when an active low-viscosity lava flow develops a continuous and hard crust on the surface, which thickens the walls while the lava cools down and forms a roof above the still-flowing lava stream which in the same time melt the rocks below and lowers the bottom.
One of the longest lava tubes is located not so far from Reykjavik as only around 30 min by car. Raufarhólshellir lava tube was created in eruption and it is totally safe to visit. This eruption created lava field stretching today along road number 39, where the cave is located.
The passage through Raufarholshellir. Near the entrance of the tunnel, three beautiful skylights were created.
While visiting Raufarhólshellir you can literally walk on the path of lava that flowed here, after the eruption of Leitahraun which took place in Bláfjöll mountain range approx. 5000 years ago.
Being in the cave gives a chance to see the secret performances of volcanic processes.
The step marks on the walls of drained tubes depict consecutive stadiums of the creation of the cave and following stadiums of lava cooling off. Inside a lava tube, you can admire a demonstration of flow ledges and flow lines – the depths at which lava flowed, depending on how conspicuously they stick out of the surface.
A floor of a lava tube may be often covered in the breakdown from the ceiling. That is why before opening the tunnel to the public metal bridges were built, making it is easier to visit.
Looking at the ceiling you can spot cross-section of the lava columns, so popular among tourists on popular Reynisfjara black sand beach in the Icelandic South Coast or recreated in the front of the Hallgrimskirkja church in Reykjavik.
The variety of colors inside the lava tunnel is astounding.
One of the characteristics of lava caves is creation of a main lava tube and a sequence of smaller tubes that supply the main lava flow. When the supply of lava stops at the end of an eruption or lava is diverted to another place, lava in the tubes drains downslope and leaves them partially empty.
When we entered one of the smaller side tubes we discovered another surprising thing about this place. The shinning bacteria, which are actually very common in this type of caves around the world.
Lava tube as a tourist attraction
Raufarhólshellir was opened to the public in 2017, but before it became a touristic attraction it was possible to explore it by yourself although it was extremely dangerous, as the skylights near the main entrance to the cave were created when the ceiling collapsed.
Before the tunnel was opened it was abundant with stalactites and today almost none are left. A variety of various cave formations may be found in lava tubes including various forms of stalactites. Sometimes changing a natural site into a tourist attraction is one of the ways to protect a place.
Thanks to observations from orbit, lava caves were also discovered on the Moon and Mars. Mars lava tunnels are considered one of the better places to set up a base and start the colonization.