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(NASA / NASA)
The surface of the Earth is not continuous. It is divided into solid segments called tectonic plates, which interlock like puzzle pieces and float on the mantle: an extremely hot layer (up to 5000 ° C), consisting of incandescent rock of pasty consistency, magma.
The place where two plates meet is a real monster clash. We ride on it and go up. The other wells – a process called subduction . Sinking means diving into the burning magma below, at depths greater than 100 km. Not very tasty. The unlucky, of course, melts.
The walnut twists its tail: "A part of the magma formed, less dense, goes back to the surface in the form of lava", explains the geologist Fábio Machado, Secretary General of the Brazilian Society of Geology (SBG). . This lava winds through the tectonic plate and melts its fragile stretches.
If this clash of plates on the open sea, the lava leak on the top of the plate forms an underwater volcano. Underwater volcanoes are full of potential. As the lava comes into contact with the water, it solidifies and forms a pile of rock. This mound grows more and more – it can even grow enough to emerge above the waterline. When that happens, we have a new island.
In the last 150 years, only three islands born this way have survived long enough to appear on the map. Indeed, this type of volcanism, called "volcanism in the bow of the islands", is quite violent. If the lava contains more than 60% SiO 2 (silicon dioxide, or simply silica, sand base), the risk of explosion increases considerably. Too much gas generates pressure and does not help. Few of these islands last more than a few months.
A very recent case of island arch volcanism is a puzzle for NASA. In late December 2014, a submarine volcano in the Pacific just outside the kingdom of the Tongan Archipelago, entered a hostile eruption. The column of smoke, ash and rocks reached 9 kilometers above sea level and the planes had to be hijacked.
When the rocket was over, more than a year later, in January 2015, an island was high, with a peak of 120 meters above sea level. It still has no name, that is why it is called the neighboring islands: Hunga Tonga-Hunga Ha'apai.
The said, whose counter-hand of all expectations, is already firm and strong for 3 years, surviving erosion caused by the impact of the waves with the terrain. You can see a time interval growth in the video below. This is the first time that a large island is born under satellite surveillance. This is a unique moment for science: we have never had so many tools to track the phenomenon. Now, after watching the young island at a safe distance, the crew of Dan Slayback of the Goddard Space Flight Center NASA was finally able to land there. The emergence of islands is of great interest to the world's science specialists. It can help us understand the formation of Martian relief as well as it helps to understand the relief of the Earth.
They brought a surface that, judging from the satellite imagery, appeared to be black sand (very dark gray that can be formed by the granulation of igneous rocks). They understood that it was actually a very thick gravel that was hurting barefoot. The beans were the size of a pea. Some plants, whose seeds were probably introduced into the stomach of birds, were already thriving. An owl had made a nest.
The weirdest thing, though, was mud. A mud that looks like clay, lighter in color than the relief. "It's very sticky, we do not know exactly what it's all about, and we're still a little confused as to where it came from, it's not volcanic ash," Slayback said in a statement. blog post about his journey on the islet. The mud is expelled by the volcano's cone, which is at the bottom of the photo below:
– – (Dan Slayback, Goddard Space Center / NASA)
L & # 39; erosion of the walls in volcanic rocks is quite intense – so, it is estimated that the island will last 30 years. It is little related to the long history of the Earth, but scientists have ample time to follow it, just like the childhood of a small piece of land. The NASA team used drones and highly accurate GPS equipment to improve the information already collected by the satellite.
"The goal is to take the satellite images and badociate them with a known reference point, preferably a vertical elevation," says Slayback. "The software that generates 3D maps does not work well in remote places like this, sometimes with GPS, you look at the water and you are told that you are at an altitude of four feet. must say no, you are at sea level. "
Good luck, little island. SUPER expects you to last a little over 30 years – it would be nice to visit you after the trees grow.
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