Could there have been cracks in the earth in Lisbon itself during the great Lisbon earthquake of 1755?

Question

There are eyewitness accounts of great holes opening up in the ground during that earthquake, but modern research seems to suggest that the epicentre was some distance away under the North Atlantic. Probably garbled accounts of the sea withdrawing during the tsunami?

Lisbon is built on a series of extinct volcanic domes

Answer 1

There is a book that was popular many years ago, which I've seen yet in a few libraries. It is called "Southern Folklore" (I believe). Anyway, there were two Young trappers on the east side of the Mississippi river, near the New Madrid area when the earthquake happened at the beginning of the 1800s. The youngest of the two, writing later, stated that during the time of that earthquake there were ripples in the earth itself of a 15 foot height. The trees whipped back and forth as these waves passed, snapping them in half, and the earth opened up and closed as great gaps appeared and then shut. The lake were they were hunting beaver drained into these cracks and then was expelled as they slammed shut. At the end of the earthquake the lake was gone.

I expect there could be "wild" things happens according to the type of rock the energy passed through. If I remember correctly, the rock in that area is limestone, rather soft stone. Granite and other hard rock, who knows what would happen?

Answer 2

The 1755 earthquake, despite being centred some distance away from Lisbon, could have re-mobilized ("fluidized") soft sediment in the estuary adjacent to Lisbon. This is a common, albeit poorly-appreciated aspect of earthquake activity. I do not know much of the details of the geology of the Bay of Lisbon. That said, any buildings located over the soft, uncompacted estuarine sediments could have easily succumbed to destruction via subsidence as a result of soft sediment fluidization and dewatering. I believe that fluidization of this type was also responsible for many of the phenomena associated with the Mississippi quake quoted by "noddarc" above.

The 1755 quake was certainly a big one, which destroyed much of the old city of Lisbon. The effects of the Tsunami were felt even as far away as the south coast of England.

Answer 3

yes there is a chance that cracks could have appeard in the earth, but that would depend upon the geology of the area, but i can see the point of the withdrawal of the sea becasue of the tsunami