In their research, the scientists point to an earthquake that occurred off the coast of Portugal in 1755, which destroyed the city of Lisbon, and a 7.9-magnitude quake that struck the Portuguese capital in 1969. Duarte describes the newly-found “structure” in the tectonic plate as “a very good candidate” for the source of these events. “The 20 upper kilometers [12.4 miles] of the plate is made of soft rocks that are light and the bottom is dense and heavy (because the plate is very old, more than 100 million years),” Duarte told Fox News. “This causes this lower part to...