The history of the Azores archipelago, from its discovery and settlement in the first half of the 15th century through the present, is marked by the social and economic impacts produced by earthquakes, mainly the high-intensity ones. Information that has been compiled leads to the conclusion that in this period, 33 earthquakes with intensity equal to or greater than VII have affected the Azores, which caused approximately 6,300 deaths and widespread destruction on some islands of the archipelago, principally S. Miguel, Terceira, Graciosa, Faial, S. Jorge and Pico Islands. The accommodation of strain resulting from the dynamics of the Azores triple junction (ATJ) plate boundary and volcanism, which also occurs in the region, are the main factors responsible for the intense seismic activity in this archipelago. This work reviews the scientific issues of the known earthquakes that have severely interfered with the lives of the Azorean people throughout their history, which we call large earthquakes.

This work describes the most important earthquakes (I > VII) that took place in the area close to the Vega Baja of the Segura River. From new works related to the seismicity of the area and considering the known historical documents, an individual analysis of each earthquake in order to assign the parameters of location more accurately is carried out. A new assessment of the points of macroseismic intensity, allowing in some earthquakes to determine its size, either in terms of moment magnitude or maximum intensity, is also conducted.

En este trabajo se presenta un estudio de los catalogos que recogen los terremotos de la peninsula Iberica sucedidos antes de 1900. Entre los primeros catalogos globales anteriores a 1800 destaca el de Moreira de Mendonca (1758) publicado despues del terremoto de Lisboa y en que se recopilan 45 terremotos en la peninsula. Los catalogos globales posteriores a 1800 recogen un numero mayor de terremotos en la peninsula correspondiendo a los de mayor tamano. El que contiene mas terremotos de la peninsula es el de Mallet y Mallet (1858) con 110 terremotos. Entre los terremotos contenidos en varios catalogos se han seleccionado 21 considerados los mas importantes. El primer catalogo regional de terremotos de la peninsula es el de Perrey (1847) con 220 terremotos. En otros catalogos regionales aumenta el numero de terremotos recogidos, el de Navarro Neumann (1921) contiene 260 y 1200 el de Galbis (1932). A partir de estos catalogos se han desarrollados los catalogo modernos en los que se introduce la cuantificacion de la localizacion (epicentro) y tamano (intensidad y magnitud). Para los terremotos anteriores a 1900, el catalogo mas completo es el de Martinez-Solares y Mezcua (2002) que incluye 2417 terremotos. El desarrollo de los catalogos es importante para el estudio de la sismicidad y el riesgo sismico.

Algeria has experienced many destructive earthquakes during the last few centuries (e.g., Ayadi and Bezzeghoud, 2015). The city of El Asnam (formerly Orleanville, today Chlef) was severely damaged in 1954 and 1980 by magnitude 6.7 and 7.3 earthquakes, respectively. On October 10, 1989, a magnitude 5.9 earthquake struck the Mont Chenoua-Tipasa coastal area approximately 150 km west of Zemmouri, which is where the May 21, 2003 earthquake occurred (Mw6.8). Many other large historical and instrumental earthquakes have severely damaged the coastal cities of Algeria over the last few centuries (i.e., around Algiers, Oran, Mascara, Djidjelli, Constantine and Bejaia). These earthquakes suggest active deformation of the margin in conjunction with the clear offshore extent of active coastal faults. According to several studies, the main active geological structures around El Asnam, Algiers, Zemmouri and Boumerdes have experienced several disastrous earthquakes. Many other earthquakes have occurred in and around the Chlef and Mitidja Basins, underlining the seismic activity in the area. In this chapter, we highlight the main characteristics of the two largest earthquakes that have occurred in Algeria in the modern period: the El Asnam earthquakes of September 9 (Mw6.7) and October 10 1980 (Mw7.3), and the Zemmouri-Boumerdes earthquake of May 21, 2003, (Mw6.8).

The 11 May 1624 Fez earthquake is one of the worst natural disasters in the history of Morocco, and caused serious damage in the city of Fez and its surroundings. It occurred in one of the most active seismic zones in the country, and in an area that is now densely populated. The 1624 earthquake occurred at a crucial time in the history of Morocco (decline of the Saadian dynasty and outbreak of internal wars) which explains the lack of sufficient information on the extensive devastation that resulted from the earthquake. We consulted several Moroccan and European sources, whenever possible first hand. A complete historical review of testimonies and journals of the time describing this particular earthquake has been carried out. Correlation these effects with the local geological setting and the most recent seismological data shows that the focal region of the 1624 Fez earthquake is likely to be located somewhere along the E—W trending Rides Prerifaines, the main frontal thrust of the Rif. An evaluation of the magnitude of the earthquake is proposed, on the basis of existing empirical relationships. Understanding this earthquake may improve the seismic hazard assessment of the region.

Catalonia, in the NE part of the Iberian Peninsula, was shaken by large earthquakes in the XV Century. As these are the largest events consigned in the regional catalogues of seismicity, a proper knowledge of their epicentral parameters and their effects is essential for any further analysis of regional seismic hazard and risk. We review the present knowledge of these important events and some applications of the obtained results for the calculation of scenarios and other products really useful for civil protection for present earthquakes.

The Montesa (Valencia) earthquake of 23 March 1748 and the Orán (Algeria) earthquake of 9 October 1790 caused heavy damage and were felt over a wide area. The abundant contemporary documentation about the damage caused by these earthquakes, allows a re-evaluation of the seismic intensity distribution giving a maximum intensity I = IX (EMS-1998) for Montesa and IX-X for Oran. From intensities distribution it is possible to correlate the seismic ruptures with the geological faults in the epicentral area. For the Oran earthquake we propose an off-shore focus due to the occurrence of a tsunami. The Montesa and Oran earthquakes have occurred in a region considered of low seismic hazard where few large earthquakes have happened.

In northern Algeria, large earthquakes occurred in the past as the El Asnam earthquake of October 10th, 1980 (Ms:7.3), one of the strongest event ever recorded in the western Mediterranean region. There were located mostly in the Tellian Atlas, some of them off the coastline as the Algiers (1365), Oran (1790), Djidjelli (1856) earthquakes or the last Boumerdes earthquake (2003). On land, no strong earthquakes have been recorded in the High plateaus or along the Saharan Atlas. From a synthesis of seismological or geodynamical studies carried out on the Algerian seismicity, we conclude that these main events along the African-Eurasiatic plate boundary are representative of the actual deformation pattern of the different geological domains of northern Algeria. They are generated mainly by reverse faults or strike slip faults in relation with the NW-SE to NNW-SSE stress regime (σ 1 striking N330°- N350°) inherited from the oblique convergence process between the two main plates in the western Mediterranean region. They are in general superficial located in the upper part of the crust (no more than 20 Km). Important earthquakes do not occur very often in Algeria in comparison with other seismic regions of the world. Their return period are estimated in some regions to be of many hundred of years. Large earthquakes still cause important damage to cities and villages, sometimes with the loss of thousand of citizens.