O OVGA é um Centro de Ciência que desenvolve atividade de investigação aplicada e de divulgação científica na área da Vulcanologia, da Sismologia e da Geotermia.
Africa Is Splitting in Two and Here’s the Proof [África está a dividir-se em dois, conforme se prova adiante] (texto original em Inglês) - Notícia OVGA 03-04-2018
Kenya's Rift Valley Split
A piece of East Africa is expected to break off the main continent in tens of millions of years. And if you need any proof, look no further than Kenya's Rift Valley, where a giant, gaping tear opened up following heavy rains and seismic activity, according to Face2Face Africa.
The enormous crack appeared on March 19 and measures more than 50 feet (15 meters) wide and several miles along, Face2Face Africa and other news sources reported. Moreover, it's still growing longer.
The rift is likely a sign of things to come as the plate tectonics under Africa rearrange themselves. The majority of Africa sits on top of the African Plate. However, a long, vertical piece of eastern Africa lies on top of the Somali Plate. This juncture where the two plates meet is known as the East African Rift, which stretches an astonishing 1,800 miles (3,000 kilometers), or about the distance from Denver to Boston.
To avoid confusion (given that Africa doesn't sit on only one plate), researchers call the giant African plate the Nubian Plate. In essence, the Nubian and Somali plates are being split in two, according to a piece in The Conversation by Lucia Perez Diaz, a postdoctoral researcher at the Fault Dynamics Research Group at Royal Holloway, University of London.
Here's how two plates split apart: The lithosphere, which is broken up into tectonic plates, is made of the Earth's crust and the upper part of the mantle. When the lithosphere experiences tugging forces, it becomes thinner, until it eventually ruptures, Perez Diaz wrote. This rupture has already led to the formation of the rift valley.
Como se forma um rifte
The rupture process is often accompanied by seismic activity and volcanism. In the East African Rift's case, a large mantle plume under the lithosphere is weakening it, allowing it to stretch, Perez Diaz said.
Rifts lead to recognizable land formations — that is, a series of depressions surrounded by higher ground. The East African Rift has a series of rift valleys that can be seen from space. However, not all of these rifts formed at the same time. Rather, they started in northern Ethiopia about 30 million years ago and spread southward toward Zimbabwe at an average rate of between 1 and 2 inches (2.5 and 5 centimeters) a year, Perez Diaz said.
According to Kenyan geologist David, the origin of the movements is probably a shield volcano called Suswa that lies at the base of the Great Rift Valley with a history of tectonic and volcanic activity.
“You cannot stop a geological process because it occurs from deep within the crust of the Earth,” he said, adding that more studies need to be conducted to understand the geology of the area and map the fault lines.
As the Somali and Nubian plates move apart, the region can experience earthquakes, as it did in southwestern Kenya last week. The giant crack tore the busy Mai Mahiu-Narok road in two and split apart houses, including the home of a 72-year-old woman who was eating dinner with her family when it happened, according to Face2Face Africa.
A bird's-eye view of a gorge in the East African Rift at Engaruka, Tanzania.
Credit: Ulrich Doering/Alamy
Vídeo disponível em: https://www.youtube.com/watch?time_continue=1&v=wO7s5zIhX6k