Researchers have finally unraveled the mystery behind Europe’s largest earthquake that struck Lisbon in 1755, killing tens of thousands in deadly calamity.
Researchers from the University of Lisbon in the recent study have found a piece of tectonic plate sinking in an area of the Atlantic Ocean under the Iberian Peninsula.
According to the findings, the piece was responsible for an 8.6 magnitude megaquake which was earlier considered an unknown seismic phenomenon.
The phenomenon called “lithosphere delamination” is responsible for causing such unprecedented seismic calamities. Earlier, this phenomenon had been observed on continents.
The study utilized sophisticated mapping techniques on a vast dataset from hundreds of land and ocean-bottom seismometers to construct a detailed model of the Earth’s structure down to 800km deep.
Beneath the Horseshoe Abyssal Plain, a region between the African and Eurasian plates, the researchers found a high velocity anomaly that is considered to be a sign of dense, sinking material.
The research also found that a portion of the oceanic plate is peeling away and sinking into the mantle. Due to which, there are deep faults but no obvious signs on the surface.
This process explains the genesis of massive historical quakes in the region.
Co-author of the study, Dr. Chiara Civiero from the University of Trieste stated, “This discovery opens up new avenues for understanding the evolution of the very early stages of oceanic subduction with important implications for plate tectonics.”
“If even areas without obvious surface faults, such as Horseshoe Abyssal Plain, can be subject to strong earthquakes, there is a need to revise seismic hazard models to include deep processes and structures that cannot be mapped using traditional methods.”