Fifty years ago, a giant earthquake hit off the coast of Portugal that caused a tsunami that killed over a dozen people. Two hundred years before that an earthquake hit the same spot, killing more than 100,000 people and destroying Lisbon. The interesting thing about the earthquakes is they were far away from faults or cracks in the Earth’s crust. There is one idea that a tectonic plates is peeling into two layers.
For more info, please read the original article by LiveScience: