A recent study published in the journal Geology suggests the Atlantic Ocean’s looming fate that it could be swallowed by the expanding subduction zone known as the ‘Ring of Fire.’
The research by the University of Lisbon focuses on the subduction zone beneath the Gibraltar Strait, also known as the Gibraltar arc, which stretches between Portugal and Morocco. This subduction zone can expand westward into the Atlantic Ocean and swallow it.
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Understanding the Gibraltar subduction zone
In geological terms, the Gibraltar subduction zone’s shift is expected to happen soon, likely in about 20 million years.
Tectonic plates are constantly moving slowly, causing oceans to disappear and form over millions of years as these plates come closer and separate from each other. Such a process is known as the Wilson Cycle, which formed the Atlantic Ocean when the Pangaea supercontinent broke down and the Tethys Ocean was squeezed.
Subduction zones are places where tectonic plates are pushed under each other, usually causing earthquakes and volcanic eruptions. These areas often happen at converging plate boundaries.
The Atlantic Ocean has two recognized subduction zones – the Lesser Antilles subduction zone in the Caribbean and the Scotia arc near Antarctica.
It is a stretch of water where the Eurasian and African Plates meet. In this region, the African plate is moving downwards below the Eurasian plate, posing a high risk of earthquakes.
The Gibraltar subduction zone began moving 30 million years ago when it formed along the northern coast, which is now the Mediterranean Sea. However, it has stayed the same for the past 5 million years, leading to questions about whether it is still active.
The subduction zone’s shift towards the Atlantic Ocean
Professor João Duarte, a faculty of sciences from the University of Lisbon, has suggested that the subduction zones can expand, a concept referred to as “subduction invasion.” According to him, the study indicates that subduction invasion may have already been underway in the Atlantic.
Duarte’s team created a 3-D model to predict the fate of the subduction zone over the next 40 million years. They found it will gradually move through the narrow Gibraltar Strait over the next 20 million years. After this, the speed of the Gibraltar arc will increase, making the subduction zone wider and expanding into the ocean.
After it enters the Atlantic Ocean, the subduction zone will become more active, leading to the closure of the ocean over millions of years.
Image Source: Duarte et. al., 2024
The 3-D model uses gravity to predict the expansion of the subduction zone beneath the Gibraltar Strait into the Atlantic, creating the Atlantic subduction system. This research is the first to demonstrate the invasion directly.
Duarte highlighted the importance of modern tools and computers in modeling the system. He mentions that these resources were only available recently. He adds that we can now stimulate the formation of the Gibraltar arc with great detail and predict what will happen.
This work shows that the Gibraltar subduction zone is active, which poses the risk of earthquakes in the region. The 1755 Great Lisbon Earthquake, which caused about 12,000 deaths, is a reminder of how vulnerable the area is to earthquakes and the ongoing need for preparedness.
