**1. Introduction**

The Ibero-Maghrebian region comprises the southern part of the Iberian Peninsula, (including Andalusia, Murcia and Alicante) and North Africa from the Atlas range to the Mediterranean sea, bordering Tunisia to the east and the Atlantic coast of Portugal to the west, embracing Morocco and Algeria [1]. The seismicity of this region is characterized by the N-S to NW-SE convergence between Eurasian and Nubian plates [2]―with a possible rotational axis to the north of Canary Islands― and by the occurrence of shallow earthquakes (<30 km).

Along this area, between January 1, 1950 and December 31, 2019, 198 earthquakes of magnitude M≥5 took place and, of these, 42 shocks (21%) reached intensities ≥VI (**Table 1**). The most destructive event was that of El Asnam (Algeria) on September 9, 1954 with intensity X-XI [3]. However, the largest earthquake in magnitude was that of February 28, 1969 (Mw = 7.8), located in the Horseshoe Abyssal Plain, southwest of Cape St. Vincent [4]. This one caused a widespread destruction in Portugal, Spain and Morocco, and a moderate tsunami recorded in the tide gauges of Cascais (93.2 cm), Lagos (84.3 cm), Cádiz (28.4 cm) [5], La Coruña (12 cm),


**301**

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

**Date Time Lat. Long. Depth** 

Chipiona (30 cm), Santa Cruz de Tenerife (0.17 cm) and Casablanca (120 cm) [6]. On the other hand, the shallowest earthquake (depth = 1.4 km) and the second most damaging in this list, with ≈15,000 dead and 70% of all new buildings ruined [7], was that of February 29, 1960 in Agadir (Morocco), considered as a moderate

*Earthquakes felt with intensity* ≥ *VI in the Ibero-Maghrebian region between January 1, 1950 and December* 

**(km)**

2004/12/04 10:29:59 349.796 −29.722 6 VI 5.0 Mw Hasssi Berkane.

2006/03/20 19:44:23 366.736 55.604 — VII 5.1 Mw Bejaia.AL 2006/04/02 06:44:31 349.373 37.942 — VI 5.4 mb Bou Saada.AL 2008/02/01 07:33:41 368.223 35.288 12 VI 5.0 mb Boumerdès.AL 2011/05/11 16:47:26 377.175 −17.114 4 VII 5.1 Mw Lorca.SP 2016/01/25 04:22:01 356.004 −38.056 12 VI 6.3 Mw South Alboran

**Int. Mag. Epicenter**

MR

These initial considerations show us that the effects of earthquakes are not merely a proportional relationship between magnitude and intensity; moreover, there are some other parameters and more deterministic in terms of vulnerability, such as the distance from the epicenter to populated areas, the depth of the hypocenter, the geological characteristics of the soils and, mainly, the quality of the buildings regarding to the construction techniques, pattern, materials and antiseis-

To explain the effects of earthquakes on buildings using the same analysis criteria, we will use as reference the 1998 European Macroseismic Scale (EMS-98) [8], based on the MSK scale, consisting of twelve incremental levels of intensity in Roman numerals (I-XII) and six vulnerability classes identified by the first letters of the alphabet (A, B, C, D, E and F). The scale also distinguishes and describes four types of structures (masonry, reinforced concrete, steel and timber) of which we will focus on those of masonry and reinforced concrete (hereinafter, RC) without earthquake-resistant design (ERD), the most common in the Ibero-Maghrebian region. Both types of construction, masonry (non-engineered) and reinforced concrete (engineered), present a vulnerability class A, B or C; classes D, E or F, require the implementation of moderate or high ERD measures or the use of steel or timber as the main construction material, unusual within the study area. Here, as we will see later, the buildings share similar construction patterns and offer up the same level of resistance: vulnerability class A or B for masonry buildings, with the exception of those made of massive stone or ashlars (class C), and vulnerability class C for RC buildings. We will prove, for example, how a building of class A located in the Algarve (Portugal) is very similar in terms of construction pattern to another of equal vulnerability in Ait Kamra (Morocco); or how a building of class C in Lorca (Spain) can be damaged in the same way as a similar one in Al Hoceima. With respect to the classification of damage, which is carried out by direct observation in the field, the EMS-98 scale considers five levels: grade 1, negligible to slight damage; grade 2, moderate damage; grade 3, substantial to heavy damage;

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

earthquake compared to its magnitude M0 = 6.0.

*31, 2019. Source: Instituto Geográfico Nacional (IGN).*

mic design, which is the subject of this chapter.

**2. Method of analysis**

**Table 1.**

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


**Table 1.**

*Natural Hazards - Impacts, Adjustments and Resilience*

**Date Time Lat. Long. Depth** 

**(km)**

1950/04/20 17:19:14 339.000 21.000 — VI 5.1 M0 El-Gheicha.AL 1951/03/10 10:38:26 375.950 −39.750 15 VII 5.2 Mw Castillo de

1951/05/19 15:54:26 375.670 −39.170 19 VII 5.3 Mw Castillo de

1953/08/29 14:08:50 358.000 50.000 — IX 5.2 M0 Hodna.AL 1954/09/09 09:28:42 360.000 15.000 — X 6.0 M0 El Asnam.AL 1954/09/09 01:04:37 362.833 14.667 — X-XI 6.7 M0 El Asnam.AL 1954/09/10 05:44:05 366.000 13.000 — VIII 6.0 M0 Tenes.AL 1954/10/10 06:01:48 363.000 18.000 — VI 5.5 M0 Kerba.AL 1954/10/12 19:23:29 362.500 17.000 — VII 6.0 M0 Fodda.AL 1955/06/04 03:41:35 371.333 −36.467 5 VI-VII 5.1 M0 Armilla.SP 1956/04/19 18:38:54 371.917 −36.833 5 VII-VIII 5.0 M0 Purchil.SP 1956/08/16 02:09:40 369.100 −86.067 5 VI 5.0 M0 Gulf of Cádiz 1959/05/24 13:19:38 363.383 45.317 5 VIII 5.1 M0 Bordj Bou

1959/08/23 22:21:30 355.133 −32.267 20 VI 5.4 M0 South Alboran 1959/11/07 02:32:08 364.000 25.000 — IX 5.1 M0 Bou Medfa.AL 1960/02/21 08:13:33 356.517 42.500 5 VIII 5.5 M0 M'Sila.AL 1960/02/29 23:40:14 304.500 −96.167 — X 6.0 M0 Agadir.MR 1961/02/10 18:52:01 417.250 −61.967 — VI 5.2 M0 Zamora.SP 1964/03/15 22:30:26 361.317 −77.500 30 VII 6.2 MbLg Gulf of Cádiz 1965/01/01 21:38:26 357.000 45.000 — VIII 5.2 MbLg M'Sila.AL 1967/07/13 02:10:21 355.300 −0.1267 5 VII 5.0 MbLg Mascara.AL 1967/08/13 22:07:47 432.950 −0.6767 5 VIII 5.3 MbLg Navarrenx.FR 1969/02/28 02:40:32 359.850 −108.133 20 VIII 7.8 Mw SW Cape St.

1973/11/24 15:22:09 361.000 44.000 — VII 5.1 MbLg Mansourh.AL 1975/05/26 09:11:49 359.000 −176.000 — VI 6.7 MbLg Athlantic

1980/10/10 12:25:23 361.533 14.467 5 IX 6.5 MbLg Chlef.AL 1988/10/31 10:12:59 364.433 26.083 13 VII 5.4 MbLg Blida.AL 1989/10/29 19:09:14 367.483 24.333 5 VIII 5.7 MbLg Mediterranean-

1989/12/20 04:15:05 372.250 −73.917 23 VI 5.0 MbLg Ayamonte.SP 1992/10/23 09:11:08 312.200 −43.567 7 VI-VII 5.3 MbLg Morocco 1992/10/30 10:44:01 314.117 −43.833 21 VII 5.1 MbLg Morocco 1993/12/23 14:22:35 367.800 −29.367 8 VI-VII 5.0 MbLg Berja.AL 1994/08/18 01:13:07 354.783 −0.1417 5 VII 5.7 MbLg Mascara.AL 1997/05/21 23:50:45 427.833 −72.583 13 VI 5.1 MbLg Triacastela.SP 2003/05/21 18:44:19 368.187 37.203 — IX-X 6.6 Mw Boumerdès.AL 2004/02/24 02:27:46 351.563 −39.841 — VIII 6.2 Mw Al Hoceima-

**Int. Mag. Epicenter**

Locubán.SP

Locubán.SP

Arreridj.AL

Vincent

Ocean

Algeria

Tamassint.MR

**300**

*Earthquakes felt with intensity* ≥ *VI in the Ibero-Maghrebian region between January 1, 1950 and December 31, 2019. Source: Instituto Geográfico Nacional (IGN).*

Chipiona (30 cm), Santa Cruz de Tenerife (0.17 cm) and Casablanca (120 cm) [6]. On the other hand, the shallowest earthquake (depth = 1.4 km) and the second most damaging in this list, with ≈15,000 dead and 70% of all new buildings ruined [7], was that of February 29, 1960 in Agadir (Morocco), considered as a moderate earthquake compared to its magnitude M0 = 6.0.

These initial considerations show us that the effects of earthquakes are not merely a proportional relationship between magnitude and intensity; moreover, there are some other parameters and more deterministic in terms of vulnerability, such as the distance from the epicenter to populated areas, the depth of the hypocenter, the geological characteristics of the soils and, mainly, the quality of the buildings regarding to the construction techniques, pattern, materials and antiseismic design, which is the subject of this chapter.
