The unique geological origin of the island makes it a real research center
Thingvellir National Park is one of the must-see places in Iceland. It is located in the southwestern part of the island, about 45 kilometers from the capital, Reykjavik, and together with the Gullfoss waterfall and the Haukadalar valley of geysers forms the so-called "Golden Circle" - the most popular tourist route in Iceland. It became the first protected area of the country, which was recognized as the heritage of mankind by UNESCO in 2004.
The landscapes presented in the park amaze with their diversity: cracks, gorges, waterfalls, rivers, lakes - a real sanctuary for Icelanders. It was here that the first parliament in Europe was founded in 930, and there you can also observe with the naked eye how Europe is moving away from North America by about two centimeters a year.
“You can put one foot on the N American tectonic plate and the other on the Eurasian plate and say that there is a mid-ocean ridge right below you. This is not common,”says José Luis Fernández-Turiel, Fellow of the Spanish High Council for Scientific Research and director of the Institute of Earth Sciences. Jaume Almery.
Iceland is generally a unique place, a planetary anomaly. It is located on the Mid-Atlantic Ridge, just above the divergence of the North American and Eurasian tectonic plates. In such areas, where fragments move and collide that form the lithosphere - the surface solid layer of our planet, semi-molten substance - magma - often escapes from the interior of the Earth.
If it hits a continental plate on its way to the surface, a volcano will form; if the plate is oceanic, then the water quickly cools the emerging magma, and it freezes. Although new solid material is formed, it rarely forms new islands as it spreads evenly over the oceanic crust. This is because, as Fernandez-Turiel explains, “the rate at which the plates are spreading is too fast to cause this. Such a large volcanic island like Iceland is an exception in this sense, which became possible due to the anomalously large magma output."
Why such an amount of magma is formed, which makes the island grow not only in height, but also along the perimeter, remains a mystery to scientists. Along the entire ocean ridge, there is only one more similar island opposite the coast of Brazil, but much smaller. “In addition to Iceland's unique location right on the ridge, there must be some other factor behind such abundant magmatism. Geophysicists suggest that we are talking about the so-called "hot spot" - says the scientist.
Hot spots are called areas of permanent volcanism caused by thermal anomaly in some places of the earth's crust, "weak crustal zones that facilitate the movement of magmatic flows to the surface." Such points are found in various regions of the Earth, they arise above hot mantle streams, or plumes, coming from the core of the planet from a depth of almost three thousand kilometers.
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"Volcanoes that have formed over hot spots like Iceland, Hawaii or Samoa are extremely interesting for scientists, because the composition of lava in them is different than in volcanoes in other regions of the world ocean, where new crust is formed at the point of divergence of tectonic plates," - says in during the video conference Barbara Romanowicz, a researcher at the University of California at Berkeley and author of a study recently published in Science. She concludes that there is a giant reservoir of molten rock beneath Iceland, fed by the mantle plume that formed the island.
To reach this conclusion, geophysicists used seismic waves. Like X-rays, they help to complement the image of the "center of the Earth", drawn by Jules Verne in his fantasy novel, which the heroes intended to reach through the crater of the Icelandic volcano Snfells. “We used a seismic tomography technique very similar to the one used in medicine to see the brain,” explains Romanovich. Scientists have collected data on earthquakes from nearly 400 seismological stations and, based on them, calculated the speed of seismic waves as they pass through various parts of the earth's crust. Then mathematical models were applied.
At some points located between the mantle and the Earth's core at a depth of 2,900 km, accumulations of semi-molten rock were found at the base of the plumes. “In these anomalous areas, waves travel 10-30% slower,” explains Romanovich. This is due to the temperature of the substance - the higher it is, the denser the substance and the slower the speed of the seismic wave in it.
"This is strange. There must be interaction with the core of the Earth, made of iron and feeding these anomalous clusters, which explains the increase in density,”says geophysicist Jaume Pons, professor at the Department of Earth Physics at the University of Barcelona. “Iceland is made up of mantle rocks that come from perhaps the deepest layers of the planet,” adds Jordi Díaz of the Institute of Earth Sciences. Jaume Almery. "Its volcanoes are like open windows deep into the Earth."
Plume-powered volcanoes have always been a mystery to science studying plate tectonics, Pons notes. A good opportunity to get closer to the answer presented itself in 1963 and 1967, when Icelanders witnessed the formation of a new island on the southwest coast - Surtsey.
It arose as a result of a series of eruptions of an underwater volcano at a depth of 130 meters. Despite the fact that its area does not exceed 1.3 square kilometers, it is a unique pristine territory of the planet, to which only scientists have access. Since the beginning of its formation, the island has been the subject of research, first by volcanologists and geophysicists, and then by biologists who study the emergence of life on a barren rock.
The latter was launched this summer and, if all goes according to plan, two probes will be lowered into the heart of the black basalt island to a depth of 200 meters to determine how such volcanic islands form, when and how microorganisms begin to populate them and what is the role of the biosphere of the deep layers of the crust in the creation of ecosystems. One of the probes will be located parallel to the other, installed in 1979 at a depth of 181 meters, in order to compare microbial populations and see how they have changed over that time. Scientists will also analyze the biogeographic evolution of newborn islands, determining the timing of their colonization by seabirds. Another probe will investigate how hot water seeps through cracks in the volcanic craters that created the island.
Channels for both probes will be drilled in areas of the seabed not affected by the eruptions of the 60s, at a depth of about 190 meters. At the same time, scientists plan to learn more about the structure of the volcano, see how its layers are located under the seabed and how a mixture of hot water and hydrothermal minerals formed in the volcanic rock reduces their porosity, which means it helps to resist erosion. Among other things, the results of the study could provide information for thought for engineers developing materials of increased strength, like cement, from which containers for radioactive waste are built.
A song of ice and fire
On March 20, 2010, the eruption of the Eyjafjallajokull volcano in the south of Iceland began. A couple of weeks later, a large volume of volcanic ash, consisting of particles of rock, glass and sand, was released into the atmosphere. The ash cloud spread over Europe, leading to the closure of the airspace over fears that it could damage turbines and aircraft engines. About 100,000 flights were canceled, millions of passengers were affected, and airlines suffered colossal losses.
However, this was not the first time a volcanic eruption on a distant island plunged the European continent into chaos. In 821, Katla volcano, one of the largest and most active in Iceland, made it, also in the southern part of the island, which now sleeps under a layer of ice 700 meters thick.
At the beginning of 820, its eruption affected the climate: the temperature in Europe dropped sharply, such non-freezing rivers as the Seine, Danube or Rhine were covered with ice. The crops were lost, and the famine began in Europe.
It is known that volcanic eruptions can cause periods of sharp drops in temperatures. This is precisely what the scientists at Cambridge University suggested as they investigated that dark moment in European history. The relic forest discovered in the flood allowed them to prove their guess, the results of their work are published in the journal Geology.
In 2003, a flood caused by the flooding of the Tverau River exposed an area of an ancient birch forest buried for centuries under a layer of volcanic sedimentary rocks. Although there are practically no trees in Iceland today, the island was covered with forests until the colonization of the island in the late 9th century.
Scientists analyzed the tree rings of the remains of relict birches of the so-called Drumbabot forest to determine when the eruption that destroyed it occurred. It was established that this happened between the fall of 822 and the spring of 823. A study of ice and ash was also carried out, and historians compared the data with archival documents. Thus, it was possible to restore the climatic conditions of that era and determine what exactly Katla brought a long winter to Europe.
During volcanic eruptions, particles that rise into the atmosphere along with hot gas escaping from the ground - mainly sulfur dioxide particles - interact with atmospheric gases and form an aerosol that does not let the sun's rays down to the Earth, causing a cooling snap.
Christina Saez (CRISTINA SÁEZ)