"Probably the most famous of all earthquakes is that which destroyed Lisbon on Nov. 1, 1755. There were three great earthquakes (the first was the largest) at 9:40 A.M., 10 A.M. and at noon. The main shock lasted six to seven minutes, an unusually long duration. Within six minutes at least 30,000 people were killed, all large public buildings and 12,000 dwellings were demolished. It was a church day, and great loss of life occurred in the churches. A fire followed which burned for six days. A marble quay at the riverside disappeared into the river bottom laden with people. Alexander von Humboldt stated that the total area shaken was four times that of Europe."
--Encyclopaedia Britannica (1961 ed.), Vol. 7, p. 848.

     "By far the most spectacular earthquake of earlier times was that of Lisbon, in 1755. This has some claim to be regarded as the greatest earthquake on record. If it is possible to believe reports, the felt area, which was certainly more than 700 miles in radius, extended from the Azores to Italy, and from England to North Africa. A source of confusion in the reports of this shock, which makes it difficult to judge the real extent of the felt area, was the widespread occurrence of seiches,...wave movements in ponds and lakes....
     "Oscillations of this kind were observed in France, Italy, Holland, Switzerland, and England, and reports of the movements even came from Norway and Sweden, at a distance of nearly 1800 miles from the epicentre. In those countries, however, the shock was certainly not felt....
     "In 1755, the damage to Lisbon itself was very great. At that time, the city had about 230,000 inhabitants, nearly 30,000 of whom were killed, according to conservative estimates. Great numbers of people were in the churches, for it was All Saints' Day, and the time of the first Mass. The shock was followed by a tsunami (tidal wave:) about twenty feet in height, and by fire.
     "The disaster shocked all Europe, and the moralists and the wiseacres were not slow to make capital of it." --G. A. Eiby, About Earthquakes (New York: Harper, 1957), pp. 141, 142.