The Climate of Iceland

Iceland is fairly unique when it comes to climate. There are only 2 prominent seasons: winter and summer. Considering the geographical location, Iceland's winter is exceptionally mild with average temperatures ranging from 14 °F to 32 °F. Summer weather averages around 50-55 °F, with a record high of 86.9 °F (recorded in 1939). Is indicated by the map, these temperatures can indeed be viewed as mild, despite the location:

Iceland is part of a greater pressure system, referred to as the North Atlantic oscillation (NAO). This climate phenomenon consists of the fluctuations of the atmospheric pressure at sea level between the Icelandic Low and Azores High, taking place in the North Atlantic Ocean. The Icelandic Low is the semi-permanent low atmospheric pressure center found between Iceland and southern Greenland. Depending on the strength of the Icelandic Low and Azores High, the strength and direction of westerly winds and storms across the North Atlantic are effected. The NAO even effects storm paths of tropical cyclones and hurricanes.

As discussed in class, in order for a hurricane to form, there needs to be a strong Coriolis Effect, high sea surface temperature, few changes in wind speed, lots of water vapor, and convergence to trigger. That being said, though Iceland's low pressure system certainly contributes to hurricane and storm paths, it is rarely effected by such natural disasters itself.

Instead, Iceland's natural disasters seemingly always involve its overabundance of volcanic activity and earthquakes. As previously discussed in this blog, the high level of volcanic activity is due to the fact that Iceland, and specifically The Crack of Silfra is a result of, the Eurasian and North American tectonic plates meeting. However, something a little more exclusive to Iceland and other volcanic areas occurs when the ash from the volcanic eruption interacts with the water, ice, and hail to create an electric charge...AKA Volcanic Lightning!

I mean, can you really get anything more badass than volcano lightning?

The answer is no. No, you cannot get more badass than this.

Intro to Geography: Silfra and Volcanoes

There are different types of extrusive volcanoes:

Shield Volcanoes, the least dangerous type of volcano, are named for their shape which resembles that of a shield laid down onto the earth. They are wider and have a dramatically less steep slope than that of a cone volcano, as shown here:

Eruptions for shield volcanoes are not isolated, but rather occur over several points on the fractured volcano, as illustrated in the following diagram:

Iceland is home to approximately 130 volcanoes of various types. It is located over the Mid-Atlantic ridge, where the North American and Eurasian plates meet.

Skjaldbreiður, aptly named and meaning broad shield in Icelandic pictured below, erupted nearly 9,000 years ago. Shield volcanoes have slow moving effusive eruptions, where lava is poured out onto the ground. This eruption created lava fields and the basin for Þingvallavatn, Iceland's largest lake. Silfra is a fissure extending from Þingvallavatn, totaling at about 300 meters long.

Glaciers would melt from a river directly into Þingvallavatn, but the eruption of this shield volcano blocked the river. Now, for several meters, the melted glacial runoff is filtered through the porous lava rock. This filtration system is why Silfra has become such a scuba haven, offering some of the clearest diving waters and highest underwater visibility ever known.

Silfra and Plate Tectonics

Tectonic plates are the pieces of the Earth’s crust, together with the uppermost part of the Earth’s mantle, that create the lithosphere. These pieces are not stagnant, and interact with each other in different ways: convergence, divergence, and transform.

Convergence occurs when two plates slide towards each other. The denser plate moves underneath the less dense plate to create the subduction zone. The magma from the mantle creates either continental volcanoes or volcanic islands, depending on if the convergence is with continental plates against each other or oceanic plates. Trenches are also formed, and earthquakes occur across the affected areas.

Divergence is when two plates spread apart. In the ocean, this is caused by seafloor spreading. Small volcanoes and shallow earthquakes are often a result of divergence.

Tectonic plates transform if they slide next to, or grind against, each other, causing faults. Earthquakes occur along fault lines.

Silfra is the result of divergence. When the North American and Eurasian Tectonic plates moved apart, lava was pushed out from underneath the crust, eventually forming the Mid-Atlantic Ridge. The divergence is not finished, as the area continues to move apart 2 cm every year. This puts an incredible amount of tension on the surrounding area, resulting in massive earthquakes approximately every ten years.

Silfra is a tectonic fissure in Thingvellir. When it formed, an underwater spring was broken and thus Silfra was filled with incredibly clear water, allowing for the greatest underwater visibility accessible for diving.

Despite Silfra being a diving hot-spot, there are very distinct parts of the fissure that are permitted for such activities. The cave system within the fissure, though fascinating, is dangerous, and the massive earthquakes also pose a threat for safety.

Intro Blog

The Who (not the band): Lauren Sganga

• 21 years old
• 4th year student at UCD
• Psychology major with minor in education
• Engaged to a strapping lad, Nick Hernandez
• Loves any social dancing, primarily blues dancing (where she met aforementioned strapping lad)
• Also enjoys trivia nights

The Where: The Crack of Silfra, located in Iceland

Pictured: The view from above

Pictured: The view from below

The Why: Many cool reasons

• Formed as a consequence of the tectonic drift between the North American and Eurasian plates
• Is continually getting bigger, causing massive earthquakes (one approx. every 10 years)
• Water is exceptionally clear, due to being glacial meltwater which is filtered through miles of volcanic rock
• There's also a cave system
• Iceland is pretty dang fascinating