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Fig. 3 Main localities of Continental Portugal and Lisbon Region cited in this paper
Figure 2 was used as basis to define the outline of the seismic areas established
in the Construction Regulation (RSCS 1958) promoted after the meeting of 1955
(Symposium about the action of the earthquakes 1955).
From general patterns to details for the city of Lisbon (in Fig. 3 we present the
main localities mentioned throughout this paper), we find in Figs. 4 and 5 differ-
ent aspects of the distribution of the damages in the interior of the city. The first
Figure outlines the isoseismals according to Pereira de Sousa (1929) for the area
corresponding to the entire district, overlapping once more the type of superficial
geology, higher intensities being shown in the area of downtown and in the northern
part of the district. Figure 5 presents in detail the most damaged areas (intensity X)
corresponding to the outline of the city by that time, as well as the area of the impact
of the fire (Fran¸a 1978). As we can see, there is a big overlap in the outlines of the
most damaged areas by shaking and by the fire, being hard to distinguish the main
causes from the damages suffered. Also we can not forget the effect of the tsunami,
responsible by the damages from flooding along the river.
It is important to remark that a study done in the years of 1990 (Mendes-Victor
et al. 1994) for a scenery corresponding to the earthquake of 1755, using a simplified
model to represent the effect of the surface geological layers, proposed variations
of intensity (MMI) of 5 degrees, with a geographical distribution very different
from the one referred by Pereira de Sousa (1929), Fig. 4(b). More recent models
(Oliveira 2004), although based in more sophisticated developments than those used
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