It occurred where the Eurasian and African plates meet off the Moroccan coast. At Al Hoceima more than 600 people died and the tremors were felt from Gibraltar to Malaga. As I write this there is report of yet another one, this time in Eastern Turkey. We may one day be able to do something about terrorism but such natural disasters are unavoidable. Every year there are 20 earthquakes greater than 7.0 on the Richter scale.
The most famous in recent history took place in 1755 and became known as "The Great Lisbon Earthquake." It struck at 9.30 on All Souls Day, November 1st 1755 with its centre in the Atlantic, about 200km from the mainland. The quake itself lasted ten minutes with three distinct jolts. The effects were amazingly far reaching although the worst damage occurred in the south-west of Portugal. Lisbon, with 275,000 inhabitants, was the most important city to suffer damage, however severe tremors were felt in North Africa and there was heavy loss of life in Fes and Meknes. More modest damage was done to Algiers and in Spain buildings collapsed as far inland as Carmona near Seville. The quake was also reported from France, Switzerland and Northern Italy. Suspended objects were set in motion as far away as Finland, suggesting to seismologists a magnitude approaching Richter 9.0.
A devastating fire followed that burned for five days and destroyed a large part of Lisbon. Half an hour after the quake later the huge tsunami tidal wave caused heavy destruction along the coasts of Portugal, southwest Spain and western Morocco.
The water level in Spanish wells dropped and islands appeared off the Algarve. Mosques, synagogues, churches, and many other buildings collapsed in Meknes and numerous casualties were reported. Lisbon with an estimated population of 275,000 was one of the largest and most beautiful cities in Europe. Several buildings which had suffered little damage due to the earthquake were destroyed by the fire.
The Royal Palace and the Opera House were totally gutted by the flames. The Patriarchal suffered relatively little damage in the earthquake and religious services continued there during the afternoon, but the church was evacuated as the fire approached. Later the building was completely burned out.
Immediately after the earthquake, many inhabitants of Lisbon looked for safety on the sea by boarding ships moored on the river. But about 30 minutes after the quake, the large wave swamped the mouth of the Tagus, flattening the custom house. A total of three waves struck the shore dragging people and debris out to sea and leaving exposed large stretches of the river bottom. The maximum height of the waves was estimated at 6 meters. Boats overcrowded with refugees capsized and sank. The destruction was even greater in the Algarve where the tsunami dismantled coastal fortresses and in some places the waves crested to more than 30 m. Almost all the coastal towns and villages were heavily damaged, except Faro which was already protected by sandy banks. At Lagos, the waves reached the top of the city walls.
Along the Spanish coast the tsunami was much more disastrous than the earthquake, causing damage to Cadiz and Huelva. Waves penetrated the Guadalquivir, reaching up to Seville and at Gibraltar the sea rose suddenly by two meters. At Conil, near Vejer de la Frontera, the Almadraba catch of 70,000 tuna was reduced to a mere 4,000 when the sandbanks raised by the disturbance drove the fish into deeper waters and the same happened along the coast of the Algarve. This was the worse recorded earthquake in living history.