De Riftvallei: Splitsing Oost-Afrika gaat mogelijk sneller dan gedacht

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Afrika dreigt in tweeën te breken: kloof van ruim 3200 kilometer

Ooit was Afrika één grote tektonische plaat, maar 30 miljoen jaar geleden ontstond er een scheur. Die lijkt nu veel sneller uit te groeien tot een flinke breuk dan gedacht.

De verwachting was namelijk dat het nog 5 tot 10 miljoen jaar zou duren voor er een oceaan zou ontstaan tussen het oosten en westen van Afrika. Maar Amerikaanse onderzoekers schatten nu dat het nog maar 1 miljoen jaar duurt voor de afscheiding een feit is.

Aardbevingen versnellen het proces. Daardoor breekt de plaat op in een aantal slenken, vertelt Wouter Schellart, hoogleraar geofysica en geologie aan de Vrije Universiteit aan De Telegraaf. "Dat zijn een soort lange, gekke dalen. Die zorgen ervoor dat er twee nieuwe platen ontstaan.”

De scheur langs de Afrikaanse oostkust wordt nu ieder jaar 0,8 tot 2,5 centimeter breder. Waar dat door komt, is niet helemaal duidelijk. "De theorie die de meeste mensen aanhangen, is dat er vanuit heel diep in de aarde een soort superpluim, een hele grote hete massa, omhoog komt. Naarmate die omhoog komt, zorgt die ervoor dat vlak onder de Afrikaanse plaat de aardmantel in het westen naar het westen stroomt en die in het oosten naar het oosten stroomt”, aldus Schellart.

Of er daadwerkelijk sprake is van een versnelling, is volgens de hoogleraar nog speculatief. "Geologen spreken al van twee platen. Waar het nu vooral over gaat, is wanneer er daadwerkelijk een nieuwe oceaan ontstaat, zoals nu al eentje tussen de Arabische plaat en Afrika. Daar is een hele kleine oceaan aan het ontstaan, de Rode Zee.”

Negatief hoeft dat niet te zijn. "Uit riften zijn rivieren en meren ontstaan en er zijn ook de eerste mensachtigen gevonden”, legt de hoogleraar uit. Maar zo stelt hij ook: "De komende paar duizend jaar zal er niet heel veel veranderen. Je spreekt van miljoenen jaren totdat er pas een zee ontstaat.”

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Powerful vent opens at Dofan volcano as seismic crisis hits Afar region, Ethiopia

A new vent opened at Dofan volcano in Ethiopia’s Afar region, releasing powerful jets of steam, rocks, and mud on January 3, 2025. The development comes during a series of earthquakes recorded in the region since December 22 and raised concerns about a potential volcanic eruption — which would be the first on record.

A powerful vent emerged at Dofan volcano, located in the Dulecha district of Ethiopia’s Afar region, on January 3, 2025. The vent is releasing a mix of gas, rocks, and mud, suggesting an escalation in the ongoing volcanic and seismic crisis in the area. This volcano is also known as Dofen.

The activity is believed to be linked to magma intrusion beneath the surface which is a phenomenon suspected to have caused the ongoing seismic swarm.

The new vent is emitting what appears to be hydrothermal or phreatic explosive activity where groundwater heated by magma rapidly turns to steam.

Videos captured at the site show jets of steam escaping from a crack in the ground. It remains unclear whether this vent existed before the vent or formed recently because of increased seismic activity.

“It has erupted frequently from fissures parallel to the rift axis and produced young lava flows and rows of cinder cones. Similar to Fentale volcano to the south, which earlier was the main suspect of the seismic crisis, it would be indeed not entirely surprising if the volcanic activity takes place at Dofan,” volcanologist Tom Pfeiffer noted.

The seismic activity began on December 22, 2024, and included numerous shallow earthquakes with magnitude reaching up to 5.1. The epicenters are located near the Dofan volcano making it a prime suspect in this geological unrest.

The largest earthquake measuring M5.1 occurred at 22:20 UTC on December 29, 2024. Its epicenter was approximately 46 km (28 miles) north of Metahara and 119 km (74 miles) northeast of Nazret at a depth of 10 km (6.2 miles).

“Over the past few days, seismic activity in the Awash area has picked up significantly. The real number of quakes is unknown as there is no seismic network (or at least no publicly available) covering the area, and only the largest events can be identified on global networks,” Pfeiffer commented.

The Dofan volcano stands at 1 151 m (3 776 feet) above sea level (a.s.l.) and lies within the northern section of the Main Ethiopian Rift. It is known as the “smoking mountain,” and features numerous cinder cones along a 10 km (6.2 miles) north-south rift line.

The area around Dofan has displayed fumarolic activity with large amounts of sulfur deposits observed on its southern flank in history.

The potential for an eruption at Dofan shows what could be its first recorded eruption in history. Geological records suggest the volcano has produced young lava flows and extensive cinder cones during the Holocene epoch.

There are about 1 900 people living within 5 km (3 miles) of Dofan volcano, 12 450 within 10 km (6 miles), and 54 930 within 30 km (19 miles).

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Op woensdag 15 januari 2025 16:10 schreef InTrePidIvity het volgende:
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Interessant! Maar het betreft vooral het oosten van Afrika dus? In het artikel uit de OP wordt gesproken over 'een oceaan tussen het oosten en westen van Afrika', ik nam aan dat het continent gehalveerd zou worden. Maar het lijkt er meer op dat Somalië op termijn een broertje van Madagascar wordt?

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Seismic unrest near Fentale volcano persists month after rare methane emissions, Ethiopia

Nearly a month after satellites detected massive methane plumes spewing from Ethiopia’s Mount Fentale on January 31, 2025, new data shows emissions have declined since February 9—yet ongoing seismic unrest, including a magnitude 6.0 earthquake on February 14, keeps scientists and locals on high alert.

Significant methane emissions were detected from Mount Fentale, a stratovolcano in Ethiopia’s Main Ethiopian Rift, on January 31, 2025.

The emissions were identified using the “tip-and-cue” method, which integrates data from Europe’s Sentinel-5P TROPOMI satellite and GHGSat’s high-resolution sensors. This discovery is unusual, as volcanic degassing is typically dominated by carbon dioxide (CO2) and sulfur dioxide (SO2), with methane emissions being rare.

The January 31 finding was flagged by the SRON Netherlands Institute for Space Research, which monitors methane plumes for the European Copernicus Atmospheric Monitoring Service (CAMS).

GHGSat’s targeted follow-up pinpointed the source at the volcano’s crater, estimating the emission rate at 58 metric tonnes per hour.

“This was a very surprising and exciting finding; we have never detected such large methane emissions from a volcanic area before,” said Ilse Aben, Senior Scientist at SRON and TROPOMI co-principal investigator.

Experts suggest the methane may stem from a shallow geothermal or hydrothermal reservoir beneath the volcano rather than direct magma degassing.

Prof. John Stix of McGill University noted that magma beneath Mount Fentale may have migrated northeast, creating new pathways for gas escape. “It will be very interesting to see if TROPOMI detects sulfur dioxide at Fentale in the coming weeks and months, which may signify magma degassing,” he said.

Satellite imagery from the UK Centre for the Observation and Modelling of Earthquakes, Volcanoes, and Tectonics (COMET) has identified a dike—a subsurface crack where magma intrudes—extending approximately 50 km (31 miles) from Mount Fentale toward Dofen volcano.

Local monitoring agencies report continued seismic swarms and ground deformation, with GHGSat noting a decline in methane emissions since February 9, though the cause remains unclear.

“Combining the regional-level view of TROPOMI with GHGSat’s ability to pinpoint emission sources, we can detect and quantify changes in greenhouse gases from low-Earth orbit—even from areas like an active volcano site,” said Stephane Germain, CEO of GHGSat, which recently joined the Copernicus Contributing Missions program.