In December 2014, a submarine's volcano exploded in the Kingdom of Tonga in the South Pacific, spitting a huge amount of rock, ash and steam into the air. The satellites caught a cloud of material 30,000 feet high (9 km), which forced to divert air traffic in the area. A few weeks later, in January 2015, these ash settled, giving rise to a new island with a 120 meter summit.
The island was born in the middle of two elderly and was baptized as Hunga Tonga-Hunga Ha of the combined name of its neighbors. Nearly four years later, a scientific expedition has traveled to this strange ephemeral world and has discovered that it is nothing but what was seen in the satellite images.
Tonga baby island & # 39; is quite unusual. It is the third that has emerged from outbreaks in the last 150 years that have survived the erosion of ocean waves in a few months. Most people disappear very soon, but scientists believe in this can last between six and 30 years. In addition, it is fascinating because its formation can provide traces of how volcanic landscapes interacted with water on ancient Mars.
Dan Slayback, from NASA's Goddard Space Flight Center in Greenbelt, Maryland, is one of the researchers who has observed the new island since its birth.
Your goal is to try to make a 3D model of its shape and volume, as it changes over time to understand how it manages to be so resistant to ocean erosion. But the satellite images couldn't tell him everything so he started an expedition to see the island with its own eyes, explain in a NASA blog.
Upon his arrival in October, the researcher found something unexpected. The island turned out to be different from what I thought. The satellite observations seemed to show that on its southern side it had shallow beaches where it could dock.
However, the bays proved to be too steep and the waves too large to reach easily. For this reason, the team walked on the quieter north coast and took GPS measurements of the location and height of the rocks and other erosive formations visible in the satellite image.
A mysterious mud
"We saw everyone as staggering children," says Slayback about his visit. Soon they realized that the earth, which was covered by an annoying black gravel that hurt them when they left, was not as flat as it seemed of satellite. It also got their attention clay that comes out of the cone, light and sticky.
"We didn't really know what it was and it still baffles me where it comes from. Because it's not ash" moreover, the researchers were able to observe how the vegetation has begun to take root on the isthmus that connects the island with its neighbor, and the patches are probably planted by bird droppings on the flank of the volcano cone.
An owl was a surprising appearance (it probably came from one of the oldest islands and with vegetation) and hundreds of terns that had taken refuge in the rocks around the crater lake could also be seen.
The whole island collapses
Using a high-precision GPS device, the researchers took about 150 measurements to try to find out what the true height of the island is.
"I was really surprised at how valuable it was to being there personally to do this" explains Slayback. One feature that revealed was the deep erosion bells running along the volcano cone.
"The island erodes from the rain much faster than I imagined. We focus on erosion on the south coast where the waves collapse what happens. But the whole island is falling. It's another aspect that is very clear when standing in front of these huge Gorges. Well, it wasn't here three years ago, and now it's two meters deep. " points out
Back at Goddard, the researchers treat the new data and developer a more realistic 3D model on the islandwhich they will use to find out their volume and the amount of ash and volcanic matter that erupted from the venting along the edge of the underwater caldera below.
There are still major issues, such as how the superficial seabed looks over the island, and whether the hydrothermal processes can solidify the material and allow it to withstand erosion for decades to come. Slayback hopes to return next year to find more answers.
source: Judith de Jorge / ABC,
Reference Article: https://www.abc.es/ciencia/abci-visitan-extrana-isla-nasa-surgir-nada-hace-cuatro-anos-201902050838_noticia.html,