The nation of Iceland contains 34 active volcanoes such as Katla and Hekla. In
March of 2021, one of these began to show substantially elevated levels of activity,
via a swarm of earthquakes. These earthquakes have only been increasing in frequency,
and at this point scientists like myself are pretty sure that this volcano is about to erupt.
What I am referring to is the Krysuvik volcano. This video will discuss this volcanic chain, its
imminent eruption, and what hazards it might pose. Before we begin, I must stress that this video
was made on March 4th, 2021. Actively erupting volcanoes can change with very little notice,
so information from this video could rapidly become outdated.
The Krysuvik volcano is located in the far southwestern portion of Iceland. A majority
of the nation's population lives close to this volcano, as its only 21 kilometers
south-southwest of the capital Reykjavik. As we take a closer look at this volcano, we can
see how unusual it truly is. You see, Krysuvik does not have a single high peak typical of a
volcano. It is also NOT a caldera. Rather, this volcano could best be described as a 50 kilometer
long weak point in the crust which contains a series of loosely connected faults and fissures.
These faults are almost all oriented in a southwest direction,
and formed as a result of Iceland slowly being split in two by a mid ocean ridge.
During a typical eruption, lava rises to the surface and erupts at a several kilometer long
and narrow fissure. As lava spills out of the vent, it generally spreads out perpendicular
to the orientation of the fissure. It then flows downhill and follows the path of local topography.
The amount of area covered during these effusive eruptions often varies between 10
and 30 square kilometers. However, some historical eruptions have covered more than
a hundred square kilometers with fresh lava. Over the last 10,000 years, 10 eruptions have
occurred from this volcano. One such eruption in 5290 BC covered a third of the modern Reykjavik
metro area with lava. This eruption began along a fissure 11.5 kilometers south of the capital.
Over time, the erupted lava coalesced into a single 250 m wide vent known as a spatter
cone. From this cone erupted a river of lava, which allowed the lava flows to
travel a long distance before it cooled. Although lava from these eruptions often
travels to the northwest, they on occasion can travel instead to the southwest.
One example of a southwest flowing eruption occurred in 1340, which also happened to be
the most recent volcanic eruption in this area of Iceland. During this eruption, a fissure
emerged in-between two high points created by faulting and previous lava flows. Due to gravity,
the lava flowed downhill to the southwest for several kilometers until it reached the ocean.
Currently, the alert level from the Krysuvik volcano is orange. This means that although an
eruption may not happen, the science data is currently pointing towards an eruption
occurring in the near future. If an eruption was to take place at the center of the current
earthquake swarm, it would most likely flow in a southern and then southwestward direction
away from any population centers. However, these same earthquakes have indicated that
an eruption could also occur further to the north. The further north an eruption is,
the higher of a chance that it will flow northwest and reach homes and vital infrastructure.
I need to stress that the initial phase of eruptions from this area of Iceland
are also the most deadly. Although this volcano produces effusive eruptions,
large explosions can occur in a specific set of circumstances. If molten rock comes into contact
with groundwater or ice, it can cause a large explosion in what it termed a phreatic eruption.
These phreatic eruptions throw boulders several kilometers, emit a plume of ash,
and create short distance pyroclastic flows. Via a geologic map of the area,
we can see that dozens of these explosions have happened during previous eruptions. After
the initial phase of an eruption, it would pose only a negligible hazard to aircraft.
The main hazard from these eruptions are long distance lava flows. Luckily,
the lava from these flows move rather slowly, so you can easily get out of harms away.
During the next eruption, there are a number of at risk areas which may require attempts to divert an
advancing lava flow. If manpower is required, please volunteer to assist with these efforts.
As a reminder, the local government has more information than I do, so please follow their
instructions. Please stay informed, and stay safe. I hope that you enjoyed this video. If you would
like to request a specific topic, please leave a comment below!