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Review of the 1755 Lisbon Earthquake Based
on Recent Analyses of Historical Observations
C. S. Oliveira
Abstract The importance of the 1755 Lisbon earthquake is known worldwide not
only among the scientific and technical communities but also in many other disci-
plines of human kind related to the effects and consequences of the earthquake. A
re-visiting of the 1755 Lisbon earthquake is made based on the historical descrip-
tions in what regards the multiple aspects of scientific and technological background
in his smaller details as, for example, the predominant direction of shaking, the
duration of the event, the anisotropy in propagation, the enormous area of percep-
tion with its direct effects along all the Iberian Peninsula and Morocco, the water
movement in Scotland (seiches), the enormous tsunami that affected the Portuguese,
Spanish and Morocco coast, being remarkable the waves in the other side of the
Atlantic, in New Jersey. These examples illustrate that the 1755 earthquake was a
unique seismologic event for which a great deal of information already exists but,
on the other hand, still contains many unresolved problems.
We review the historical descriptions of several different physical phenomena,
compiling available data and discussing models proposed recently in the literature,
with the aim of contributing to a better characterization of the seismic source, the
wave propagation, and also to the causes behind the observations in nature, in
housing and population. The interpretations are supported, as much as possible,
on physical evidences such as the structural characterization of simple objects and
structures for which it was possible to partially recover the seismic input acting at the
foundation level. The analysis of the tsunami, of several monumental structures, and
especially the “Aqueduto das Aguas Livres”, the damage inflicted to different types
of buildings, etc., represent the essential basis to place a few pieces to reconstitute
the large and intriguing puzzle that the 1755 earthquake still is. Though science has
already given many important clues, there are yet a large number of questions to be
answered which will contribute to a full comprehension of the phenomenon and to
the definition of future hazards.
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