*4.1.2 Fonte de Louzeiros: the maximum intensity in the whole macroseismic area*

Fonte de Louzeiros is a small rural hamlet located 7 km at east of Silves. In this settlement of sixteen houses at the time, the most of buildings were total or partially collapsed. The earthquake caused all type of damage mentioned above: X-shaped cracks, corner failures, overturning of load-bearing walls and roof collapses; almost no house could be rebuilt. As an exceptional example, in **Figure 10** we can see one of the few buildings left standing and showing the patched damage of a corner failure. About 95% of these single-story buildings of vulnerability class A suffered damage of grade 5.

Some seismologists have assigned to this place intensity VIII, the maximum level of destruction in the whole macroseismic area [16], although other researchers extend this isosist, in general, to the Algarve region [4] or enclose it to the Cape St. Vincent and surroundings areas [9, 15, 17, 18]. But this particular case of Fonte de Louzeiros, with a total destruction of buildings of vulnerability class A, does not correspond to an area of intensity VIII but rather to intensity IX, or at least VIII-IX [19]. Therefore, it is consistent to raise the damage recorded in Fonte de Louzeiros to intensity VIII-IX, where "a bombing would not have been worse", literally "wiped off the map", as defined by the *Diario de Lisboa* on March 2, 1969.

#### *4.1.3 Alentejo coast, Setúbal and Lisbon: the transition to vulnerability class C*

Outside the Algarve region, the intensity of the damage decreases slightly, except along the Atlantic coast between Aljezur and Setúbal, where the effects reached

#### **Figure 9.**

*Portimão, two-story building of class B with detachment and toppling of the outer leaf of the external wall on the second floor, due to a hammering effect between the wooden joists supporting the roof and the top of the loadbearing walls (grade 3). The lack of shear cracks indicates a ground displacement from back to front. Source: IPMA.*

#### **Figure 10.**

*Fonte de Louzeiros, building of class A rebuilt after the 1969 earthquake, showing the repair mark of a corner failure (dotted line). Inside the white circle is visible the red color of the clay used to join the adobe masonry. Source: Google Earth.*

**309**

*IPMA.*

**Figure 11.**

*Effects of Earthquakes on Buildings in the Ibero-Maghrebian Region*

intensity VII, or VI-VII in the Lisbon district. In São Teotónio, Longueira, Vila Nova de Milfontes, Cercal and Sines, midway between Cape St. Vincente and Setúbal, many houses of class A collapsed. The rural village of Longueira, completely built with the same construction techniques of the Algarve, was razed; and the same situation occurs in Vila Nova de Milfontes and Cercal, where only the RC buildings (class C) performed well. In Odemira, partial roof collapse can be observed in buildings of class A (grade 4), due to the hammering effect of the wooden logs supporting the roof against the top of the load-bearing walls, to which they were not well anchored (**Figure 11**). Compared to the previous locations, the city of Sines felt abnormally strong vibrations of soils, probably influenced by geological conditions and site effect. Some houses of class A or B total or partially collapsed (grade 4 or 5) and other buildings of class C as the City Hall, the church of São Salvador and the hospital suffered significant damage with fall of apparently non-structural elements. Further north along the coast, in Grândola, 38 km northeast, buildings of class B (simple stone) had a good behavior with some shear cracks and detachment of nonstructural elements (grade 1 to 3), but twenty houses of class A (adobe masonry) had to be rebuilt of demolished because of corner failures, overturning of load-

bearing walls, roof collapse and fall of plaster and cornices (**Figure 12**).

quences as we will see later when analyzing the 2011 Lorca earthquake.

*Odemira, damage of grade 4 in adobe masonry house of vulnerability class A: (a) detachment of plaster; (b) partial roof collapse due to the strong pounding of wooden logs against the top of the load-bearing wall. Source:* 

Finally, in Setúbal and Lisbon the structures of vulnerability A and B had been widely replaced a long ago by those of class C (monumental and RC buildings), contributing to a lower level of destruction. Even so, in Setúbal some old houses collapsed, and shear cracks arose everywhere. Ceramic shops were specially shaken, with high material losses of facilities and merchandise. The factory of Pinhal Novo, built of RC supporting structure with hollow clay floor slab blocks over RC beams (class C), became a mountain of debris (grade 5), due to the scarce rigidity of column-beam joints and the use of smooth steel rods (not corrugated) within the core of RC frames. The information available for Lisbon allows us to assess damage of grade 2 in buildings of class C and grade 3 for class B, with a lot of cars buried in rubbles by the fall of plasters, bricks, cornices, eaves, chimneys, balconies, windows and other non-structural elements form buildings of class C, with similar conse-

*DOI: http://dx.doi.org/10.5772/intechopen.94739*
