The effects, combined with a large tsunami or tidal wave triggered by the earthquake, are devastating.
Estimates of fatalities vary, but may be as high as 200,000.
The quake's magnitude is equal to 7.5 on the modern Richter scale.
"The crash of falling houses, the tottering of towers, and the groans of the dying, all contributed to raise my terror and despair," writes one eyewitness.