*4.2.1 Severe damage limited to Guadiana/Guadalquivir strip*

In Spain, as happened during the earthquake of November 1, 1755, the shocks were felt most strongly in western Andalusia, near the border with Portugal, along the strip between the rivers Guadiana and Guadalquivir. It is undoubtedly due to the increasing human settlement on young soils formed by sedimentary alluvial deposits from both rivers, tributaries streams and other intermediate rivers such as Tinto and Odiel. In the city of Seville, the seismic event caused a widespread partial fall of non-structural elements in buildings of class B or C (as in Setúbal, class A is not very representative, practically nonexistent) and moderate damage not higher than grade 3 to monumental buildings (class C) as La Giralda, Torre del Oro, Alcázar, Museum, Navy Command Headquarters, City Hall, Telefónica building, Post Office building and Cathedral.

However, in the western half of the province of Huelva, the level of damage was remarkably similar to that of the Algarve region, due to the analogy between the construction patterns, especially with regard to buildings of class B or monumental buildings of class C (adobe masonry structures were less common in this geographical area). About 274 buildings in the city of Huelva were damaged, 1 completely ruined and 18 partially collapsed. Several photographs published in newspapers allow us to diagnose grade 3 in residential buildings of class B and grade 2 and 3 in monumental buildings of class C (Cathedral, Iglesia de la Milagrosa, the Town Hall, etc.). In the surrounding villages little damage of grade 4 or 5 was recorded, with the exception of Ayamonte and Isla Cristina.

#### *4.2.2 Widespread damage to buildings of class A and B in Isla Cristina*

Isla Cristina and Ayamonte are two Spanish towns located in the province of Huelva, at the mouth of the Guadiana River, very near the border with Portugal just 10 km from Castro Marim. Obviously, there was a very close relationship between the damage caused by the earthquake and the fact that both towns were settled over

**311**

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

7 km away, damage of grade 4 and 5 was widespread.

Therefore, the site effect is also evident in the Guadiana estuary.

sedimentary soils. In Ayamonte, a few houses that already showed a previous state of abandonment collapsed, and only were recorded a few cases of fall of beams and roofs, or cracks in some load-bearing walls and infill partitions. But in Isla Cristina,

The historical and archival reports provided to us by the Town Council of Isla Cristina ―unfortunately, there are no photographic documents― are not very descriptive in relation to the damaging effects in this place. Three expert teams that carried out the disaster evaluation limited their analysis to estimating that 65% of the total number of buildings in this municipality were damaged (≈ 350 houses), resulting 21 of them in partial or total collapse and completely uninhabitable (grade 4 or 5). With this scarce official information available and based on the photos published by the press, we can compare this level of destruction with this one observed in Bensafrim or Vila do Bispo, in the Algarve region, but in an area 130 km further away from the epicenter with respect to the Portuguese towns here mentioned.

The earthquake took place in origin (t0) at 02.40.32 UTC (IGN), but P waves reached the seismographic stations of Spain and Portugal at different times depending of the epicentral distance (UTC): Lisbon, 02.41.20; Coimbra, 02.41.41; Porto, 02.41.52; San Fernando, 02.41.30.5; Toledo, 02.42.07; Canarias, 02.42.08; Granada, 02.42.09; and Barcelona, 02.43.10. In San Fernando we take as reference the record of the official seismic bulletin of the Real Observatorio de la Armada (ROA).

Just at 03.45 suddenly stopped the clocks of the City Halls of Cádiz, El Puerto de Santa María and the Compañía de Seguros building located in Plaza de Neptuno, Madrid. In Lisbon, the clock on the main façade of the Estação do Sul (railway station) stopped at 03.44 local time (+1 UTC), although the time gap is probably due to a lack of synchronization between local and UTC time. In Huelva, the clock of the Catedral de la Merced stopped at 03.41 and in Palencia, 860 km from the epicenter, the City Hall clock also stopped at 03:45, because the machinery had come out of its gear due to the strong motion. Surely this was the same cause that made all the

The earthquake caused strong shakes in Marrakech, Safi, Casablanca, Tétouan, Rabat, Salé and Tangier, among other sites in Morocco. In Salé, two houses that already had a previous state of ruin collapsed, and in Rabat some houses in the surrounding area (class A) were ruined. However, in Agadir the earthquake had not

The available macroseismic data from Morocco is very scarce, mainly due to the coincidence of an episode of severe flooding caused by a powerful storm that left torrential rain, flash floods and rivers bursting their banks along the Atlantic coasts and in the Moroccan Atlas. In the region of Casablanca-Settat (formerly named Dukala-Abda) large areas of crop fields were flooded and affected by landslides, with three villages submerged under waters. In the city of Salé, a short distance north of Rabat, a house collapsed due to the riverine flooding of the river Bou Regreg, forcing the evacuation of its residents. In Kenitra, 35 km north of Rabat, the roads were cut by flooding and 100,000 hectares of crop fields were devastated by the rainfall. Also, 39 houses were washed away by the floodwaters 120 km north of Rabat, leaving some villages isolated. Further inland, in the middle of the Atlas, 95 houses were left with water over rooftops. These widespread floods in much of the

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

*4.2.3 Clocks*

other clocks to stop.

been felt.

**4.3 Effects in Morocco**

#### *Effects of Earthquakes on Buildings in the Ibero-Maghrebian Region DOI: http://dx.doi.org/10.5772/intechopen.94739*

sedimentary soils. In Ayamonte, a few houses that already showed a previous state of abandonment collapsed, and only were recorded a few cases of fall of beams and roofs, or cracks in some load-bearing walls and infill partitions. But in Isla Cristina, 7 km away, damage of grade 4 and 5 was widespread.

The historical and archival reports provided to us by the Town Council of Isla Cristina ―unfortunately, there are no photographic documents― are not very descriptive in relation to the damaging effects in this place. Three expert teams that carried out the disaster evaluation limited their analysis to estimating that 65% of the total number of buildings in this municipality were damaged (≈ 350 houses), resulting 21 of them in partial or total collapse and completely uninhabitable (grade 4 or 5). With this scarce official information available and based on the photos published by the press, we can compare this level of destruction with this one observed in Bensafrim or Vila do Bispo, in the Algarve region, but in an area 130 km further away from the epicenter with respect to the Portuguese towns here mentioned. Therefore, the site effect is also evident in the Guadiana estuary.
