1 Introduction

Algeria is among the most seismic zones in North Africa. The seismicity of Algeria, which is essentially concentrated in the North of the country (Fig. 1) in the Atlas Mountains (Tell and Sahara Atlas ranges), is due to the 4–6 mm/year NW–SE Africa-Eurasia plate convergence (Nocquet and Calais 2004). Algeria experienced moderate-sized and strong earthquakes in the past. Figure 2 illustrates the most damaging and destructive earthquakes that occurred in the region during its seismic history. It is worthwhile noting that light to minor earthquakes occurred and continue to take place until recently in an area remote from the plate boundary, in the Hoggar shield, near Tamanrasset (Grandjean et al. 1960; Boughacha 2005; Boughacha et al. 2006; Harbi et al. 2010; Bourouis et al. 2013). The origin of this seismicity, whether or not it is from intraplate tectonics, is still subject of debate.

Fig. 1
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The spatial distribution of earthquakes from 1970 to 2016 (M ≥ 3). Data are from International Seismological Centre, On-line Bulletin, http://www.isc.ac.uk, Internatl. Seismol. Cent., Thatcham, United Kingdom, 2014

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Fig. 2
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Spatial distribution of damaging and destructive earthquakes in Algeria (I0 ≥ VIII EMS). Data are from Harbi et al. (2015)

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The perception of earthquakes is well known by the Algerian population from north to south. Therefore, the Algeria intellectuals and scientists took an interest in understanding and studying the earthquakes from time immemorial. In this paper, a chronological approach will be adopted in order to give a quick overview on what was done so far in terms of seismology in Algeria (Table 1). The objective of this paper is not to review the studies of Algerian earthquakes, but to present a summary of some important milestones on the way of progress of seismology in Algeria. The reader will notice that this discipline almost flourishes after each damaging to destructive event, which gives a fresh start and a boost to the earthquake science in Algeria and leads to the installation/acquisition of new high-performance equipment and to sound results. We do not pretend in this article to give a definitive and comprehensive account of the history of seismology in Algeria, but just a glimpse drawn from our experience as scientists mainly involved in historical seismology research. No new investigations were carried out to recount the history of seismology in Algeria. In fact, when seeking information on past earthquakes, we have often found very interesting details, which are more related to the history of seismology than to historical seismology itself. We have gone from surprise to surprise in discovering that Algeria, a colonized, then a developing country was not so far from what was done in terms of progress of seismology in its geographical area. The work of earthquake scientists of Algeria has significantly contributed to a better understanding of seismicity and active tectonics in Mediterranean and North Africa.

Table 1 Summary of the main events of the history of seismology in Algeria between 1830 and present
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2 Pre-French Period (Before 1830)

The historical Algerian earthquake catalogue (Ambraseys and Vogt 1988; Mokrane et al. 1994; Boughacha 2005; Harbi et al. 2007a, 2010, 2015) does not span a period of time as long as the period covered by earthquake catalogues worldwide, e.g., 815 BC (the Iberian Peninsula, Roca et al. 2004), 1365 BC (Syria, Sbeinati et al. 2005), and 23rd century BC (China, Wang 2004). In fact, we know very little about Algerian earthquakes earlier than 1825. The town of Dellys (Fig. 2), which experienced disastrous effects following the 2003 Zemmouri earthquake, was alleged to have been destroyed in 42 A.D. (see Harbi et al. 2007b for more details), but until now we have found no original sources confirming the occurrence of that earthquake. As already reported in Ferdi and Harbi (2014), earthquakes were relatively frequent in Algeria in the first century. According to Beaujeu (1973), the first Algerian scientist who discussed earthquakes and tsunami is Apulée de Madaure (125–170 A.D.) in his cosmographic book “De mundo”. Little information about the earthquakes that occurred in Algeria during ancient times was found in epigraphic and literary sources such as the 267 Lambaesis earthquake and the 419 Sitifis earthquake (Ferdi and Harbi 2014).

The Algerian scholars of the Middle Ages and those from the Maghreb countries, and Andalusia who traveled to Algeria (called Central Maghreb in medieval times) used to report the earthquakes, particularly in their chronicles or when they dealt with historiography. The Andalusian scholar Ibn El-Haj Ennoumeyri (1313–1367) who traveled to Algeria and worked for some years in Bejaia, reported in his travel notes, which are collected in a book presented by Ibn Chakroun (1990), that when he was in Miliana, he read a letter of the judge of this city to the Sublime Porte (Istanbul during the Ottoman Empire) informing that three shocks occurred in 1344 in Miliana and were followed by hail that damaged some houses. In his book “History of the Algiers Pashas”, Ibn Al Mofti Hussein Ibn Rajeb Chaouche (1095H–1144H ~ 1683/1684–1731/1732 A.D.) referred to the religious scholar El Brechki who experienced the 1365 Algiers tsunamigenic earthquake, and related the effects of this earthquake and the sea wave that inundated Bab El Oued following this seismic event (see the original information on http://naget.ictp.it/PUBLICATIONS/resources/AMD.pdf, last accessed in October 2017). Until recently (Harbi et al. 2015), this event was the first, which was reported in the Algerian earthquake catalogue (Ambraseys and Vogt 1988; Mokrane et al. 1994). Ibn Al Mofti also reported the effects of the earthquakes that occurred in Algiers (1585 and 1716), Dellys (1631), and Médéa (1632). It is important to recall that the first “seismic code” or preventive measures in reconstructing the city after the 1716 earthquake were issued by the Algiers Governor, Dey Ali Chaouche. It was recommended to build the houses in such a way that the balconies lie against one another over the streets, with an additional timber propping (in cedar or eucalyptus) in order to strengthen the supports, as we may see nowadays in the Algiers Casbah (Rothé 1970; Abdessemed-Foufa and Benouar 2010).

In a book on astronomy and astrology published in 1192 H (1778/1779 A.D.), Mohamed Ibn Ali Ech-Chellati, better known as Ibn Ali Cherif, related the destructive effects of an earthquake, which occurred in his region, Chellata in 1767 (Harbi et al. 2015). In the Western world, one claim that the 1755 Lisbon earthquake served as milestone on the road of progress of seismology, which is true. This somewhat applies for Algeria and the change of Algerian scholars’ interest in earthquakes is particularly perceptible in the work of Ahmed Ibn Sahnoun Al Rachidi (1791). For the first time, one has not only a summary of the effects of the earthquake, as the previous scholars used to do, but also a detailed description of these effects and how an earthquake is perceived at the time of the author. Ibn Sahnoun Al Rachidi experienced the 1790 Oran earthquake whose disastrous effects on the population were at the origin of the departure of the Spanish who were colonizing Oran from the sixteenth century. Al Rachidi reported a famous poem of Abou Ras on the effects of the 1790 earthquake and provided us with information on the definition of an earthquake by three categories of persons of his time in Central Maghreb (Algeria now): (1) ordinary people, (2) scientists, and (3) clerics (mainly Sufis). All these points of view were detailed by Ghalem (1998) and deserve to be known. In the diary of Al Hadj Ahmed Cherif Al-Zahar (1754–1830) presented by Al-Madani (1974), one finds some details on the effects of the 1802 Kolea and 1825 Blida destructive earthquakes, and especially on the emergency relief measures taken by the Agha (civil or military officer in the Ottoman empire) toward the population. For all authors, the earthquake is just an event that they experienced since the first objective of their respective work is merely historiographical.

Over a century before the French colonization, French consuls and clerics systematically reported on the earthquakes felt in Algiers and surroundings. This was the case of the events felt in Algiers between 1716 and 1811 (more details in Sebaï and Bernard 2008). It seems that the British consuls also were used to send accounts on the Algeria earthquakes since we found in the archives two letters describing the effects of the 1825 Blida earthquake (Harbi et al. 2017). As already reported in our previous works, press reports largely contributed to the survival of macroseismic information of Algeria earthquakes. The first press report available to us comes from “La Gazette de France” of February 20, 1723 and concerned the November 29, 1722 Algiers damaging earthquake (Harbi et al. 2015). British newspapers also reported information on Algeria earthquakes such as “The London Chronicle” (1763, 1766) and “The Times” (1790, 1825).

3 French Period (1830–1962)

3.1 1845: The First Compilation of Earthquakes of Algeria

It was long believed that the first compiler of the earthquakes of Algeria is Perrey (1847). The macroseismic survey that we recently carried out (Harbi et al. 2015) has shown that the first list of earthquake appeared in 1845 and was compiled by Dr. Finot who was physician in chief of the Blida hospital. This list contains the significant earthquakes that occurred in Blida and surroundings from 1760 to 1840 and seems to be based on Arabic documents since the dates are converted from the Hegira calendar by the author. However, the Finot’s list contains less than 10 events.

3.2 1847: The Perrey Earthquake Lists

Perrey is one of the most famous compilers of historical earthquakes in Europe and Mediterranean. He published annual lists of earthquakes that occurred throughout the world from 1844 to 1871. In 1847, he published a note on the earthquakes of Algeria and North Africa and continued reporting earthquakes of Algeria in his different lists until 1869. The work produced by Perrey, while providing useful data on earthquakes of those periods, did not involve studies of historical earthquakes. The second descriptive earthquake catalogue of Algeria was published in 1892 by Chesneau. The description of these catalogues and the successive catalogues compiled for Algeria, and briefly presented hereafter, is outside the scope of this paper.

3.3 1856: First Comprehensive Descriptions of the Effects of an Earthquake, Early Attempt to Record the Ground Motion, and First Picture on the Damage Caused by a Seismic Event in Algeria

The occurrence of a destructive seismic event in Algeria has always sparked the interest in earthquakes and boosted the earthquake studies. We will see throughout this paper the progress made in seismology for better knowledge of the seismicity, understanding of seismotectonics, and assessment of earthquake hazard in Algeria.

Two destructive seismic events struck Djidjelli and surrounding areas on August 21 and 22, 1856, with an estimated intensity VIII, IX (EMS), respectively. These shocks, which triggered tsunami, are the first well-documented historical earthquakes in Algeria (Harbi et al. 2011), thanks to the wealth of information produced in the wake of these earthquakes. At the time it was the largest and most intense investigation of an earthquake in Algeria. Among all the available materials that we found with regard to these events, two detailed and invaluable reports drew our attention. These reports were made by military officers: Schoenagel (1856) and De Sénarmont (1857). Both authors reported on the underground noise heard during the shaking, the ground and hydrological earthquake effects, the tsunami effects, the damage to buildings, and the number of aftershocks and how they were felt. This was the first time when one estimates the height of the sea wave triggered by an earthquake in Algeria (see Harbi et al. 2011 for more details). Schoenagel (1856) detailed the damage to private houses and public buildings at Djidjelli by providing us with drawings, which highlight the damage to some specific buildings. He also recommended new ways of improving local constructions procedures following these earthquakes. De Sénarmont (1857) provided a clear description of all the effects at each site of the felt area and the direction of the ground motion on these sites. He reported the effects on objects, while Schoenagel reported the effects on animals. De Sénarmont wrote an additional section on the absence of any meteorological phenomenon before, during, and after the earthquake. The correlation between the occurrence of earthquakes and the atmospheric disturbance was frequently made at that time as we will see hereafter. According to De Sénarmont, a pendulum was installed in the morning of August 22 (before the earthquake) by the Engineer Maevus at Constantine. Little is known of its operation except that it recorded a ground motion in an NE–SW direction. The reports of Schoenagel and De Sénarmont were the first such accounts of destructive earthquakes and illustrate the level of the understanding about seismic phenomena at that time in Algeria. It is true that none of the authors estimated the intensity of the events; however, the way with which they synthesized the information makes it easy for any analyst to estimate and draw an intensity map for these earthquakes. 1856 was also the first year in which an engraving showing the damage caused by an earthquake (Djidjelli 1856) is published in Algeria (Ambraseys 1982).

3.4 1858: Creation of the Algiers Observatory

The Algiers Observatory was created on November 26, 1858, under the name “stations of astronomical observations.” It was under the aegis of the Ministry of Education until July 6, 1861 when it moved to the General Government of Algeria, and then it returned to the Ministry of Education on December 26, 1873. The mission of the institution consisted in making meteorological, magnetic, and astronomical observations (see http://www.obs-hp.fr/dictionnaire/observatoires.pdf). The meteorological observations included the earthquakes too. Previously located at Algiers at its inception in 1858 (Bulard 1873) then at Kouba in 1881 (Trépied 1884), the Algiers observatory moved to its present location at Bouzaréah in the outskirts of Algiers in 1885.

3.5 1864: The Earthquakes in the Algerian Scientific Periodicals

The scientific periodical “La Gazette Médicale de l’Algérie”, which was founded in 1856, started reporting the earthquakes that occurred in Algeria in June 1864 after the publication of a decree of the Marshal-Governor General of Algeria, dated February 23, 1864, prescribing the centralization of all the meteorological observations, which were daily collected in the meteorological stations throughout the country, at Algiers Observatory (see La Gazette Médicale of March 1864). From that year onward, the “Meteorological Bulletin of the Algiers Observatory” was regularly published in the Algiers Press (see Le Moniteur de l’Algérie of July 26, 1864). Other Algerian scientific periodicals took the example of “La Gazette Médicale” and published information on the earthquakes of Algeria whenever they occur (for more details, see Harbi et al. 2015).

3.6 1867: A Step Toward Teamwork, from a Simple Pendulum in 1856 to a Seismograph, First Mapping of Geological Effects,…

The year 1867 for the first time saw the beginning of a team effort by scientists while the previous earthquakes have been undertaken almost exclusively by military officers. This happened after the destructive Mouzaia-El Affroun earthquake, which occurred on January 2, with an estimated intensity IX EMS (Harbi et al. 2017), when some meetings gathering experts were organized to present and discuss the observations that the experts made. The bulletin of the Algerian society of climatology, physical, and natural sciences published in 1867 revealed (on page 294) that Cochard presented detailed explanations on the recording provided by the seismograph of the naval dockyard of Algiers after the earthquake. This was the first time when the word “seismograph” is used. After that presentation, the Society instructed Cochard, Vatonne, and Marès to prepare as complete a summary of the earthquake effects as possible. We are told, on page 297, that Cochard, the Rapporteur of a committee working on the Mouzaia-El Affroun earthquake, presented the required details and informed the Algerian society of climatology and physical sciences about the improvement that he made in the seismograph. Vatonne presented a map on the ground fissures caused by the earthquake and Marès accounted on the boreholes carried out at Oued El Alleug by the Mines service of Algiers province 1 year before (Vatonne 1866). On the other hand, Marès drew the attention of the Society of climatology, physical, and natural sciences to the increase of the water flow in August or September 1866 in the Mitidja basin. Surprisingly, it is the bulletin of the “Société de Médecine d’Alger”, which published a comprehensive report on the effects of the earthquake. The structure of this report is quite similar to the structure of the report by De Sénarmont (1857) on the 1856 Djidjelli earthquakes (see above), but with some differences. This report inter alia has addressed the following issues: (1) Physical effects, which mainly concern the damage caused to the buildings at several sites of the epicentral area; (2) meteorological phenomena with an attempt to provide the temperature at the time of the occurrence of an earthquake; (3) physiological and pathological effects; and (4) number of aftershocks, the extent of the affected area, duration, direction, and origin time (see the original information in Harbi et al. 2017). We also note the availability of several engravings and photographs on the damage caused by the earthquake at Mouzaïa, El Affroun, and Blida in contrast to the 1856 Djidjelli earthquake for which one has only one picture. These illustrations, which document damage, were very recently used as a research tool in the retrospective construction of the macroseismic field of the 1867 Mouzaïa-El Affroun earthquake (Harbi et al. 2017). It is worthwhile noting that from 1867 onward, the directors of the observatory of Algiers started to author the “Meteorological Bulletin of the Algiers Observatory”. In 1867, the Director Charles Bulard (from December 30, 1858 to 1880) sent the exact origin time (hour, minute, second) of the Mouzaia-El Affroun earthquake to the national press. Bulard used to correlate the occurrence of the earthquake with the change of temperature or the atmospheric disturbances as he often wrote in most of his reports (for the period 1870–1880) to the national press and sometimes to the scientific periodical “Comptes Rendus des Séances de l’Académie des Sciences”.

3.7 1891: Very First Questionnaires

On January 15, 1891, a destructive earthquake struck the locality of Gouraya and its surrounding villages, with an estimated intensity IX EMS (Maouche et al. 2008). It was the first time when a senior geologist (Pomel) paid attention to an earthquake in Algeria. Pomel (1891) described in details the earthquake effects in almost the same way as previous authors for the 1856 and 1867 earthquakes. He informed us that the first shock was recorded by the seismograph. He observed the first coastal uplift (30 cm) documented for an Algerian earthquake and set up the first questionnaires in order to get details on the earthquake effects at many sites and delineate the perceptibility area. Pomel said that these questionnaires, sent to the officials of the primary schools, allowed him to collect 380 useful information. Unfortunately, we could not find any of these questionnaires in Algerian archives and therefore we ignore the information that they requested.

3.8 1906: First Seismicity Map of Algeria and Its Adjacent Areas

The first seismicity map available for the Maghreb region including Algeria was drawn by Montessus de Ballore (1906). One may see from this map (Fig. 3) that Algeria was already more seismically active than its adjacent areas.

Fig. 3
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Seismicity map of Algeria by Montessus de Ballore (1906)

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3.9 1907–1910: Creation of the Service of Seismology, First Seismic Stations, Use of Reinforced Concrete…

We mentioned above that the successive directors of the Algiers observatory contributed to the circulation of information on Algeria earthquakes. This was the case of its second director Charles Bulard as previously cited. However, we could find any work or communication in the field of seismology left by his immediate successor who is Charles Trépied (1880–1907). François Gonnessiat, Director of the Algiers observatory from 1907 to 1931 gave an impulse to earthquake science and created the service of seismology under the umbrella of the “Service météorologique de l’Algérie”. Gonnessiat who was an astronomer compiled a list of the earthquakes that occurred in Algeria from 1871 to 1881 on the basis of the meteorological bulletin that Bullard sent to the newspapers “Akhbar” and “Le Moniteur de l’Algérie”.

Instrumental recordings of earthquakes became possible in the late 1800s with the development of the seismograph as one has seen for the 1867 Mouzaia-El Affroun earthquake. A description of this seismograph is available in Cochard (1867). We learnt from the archives (Harbi et al. 2015, 2017) that this seismograph installed at the naval dockyard of Algiers recorded the earthquakes of Mouzaia on September 20, 1869, Boufarik on October 16, 1873, Cherchell on March 28, 1874, and Marengo on October 22, 1882. According to Chesneau (1892), this seismograph was still operating in 1892. The only information provided by this instrument is the direction of the ground motion. One may notice from the figure drawn by Cochard that one was still at the preliminary stage of trial and error (see Fig. 4 in Harbi et al. 2017). Other seismometers were installed across the country as reported in the “Annales des sciences physiques et naturelles, d’agriculture et d’industrie” following the November 22, 1872 Mostaganem earthquake. We know from the “Echo d’oran” that the May 21, 1883 Oran earthquake was recorded by a seismometer installed at the Direction of Artillery of Oran. The astronomer Gonessiat, a tireless worker as described in the press reports whenever a strong earthquake occurs, was the pioneer in seismology at the Algiers observatory, and it really is to him that we owe the first seismic station installed at Bouzaréah in 1910. We read in the February 27, 1909 annual report of the Commission inspection of the Algiers observatory that the meteorological service is led by Gonnessiat proposing to carry out research in Earth physics. The 1911 report of the same commission informs us that a Bosh-Mainka seismograph with a 450 kg mass was installed in the basement of the library, which was specially designated to include it. In the 1914 report, one learns that the seismograph operated without interruption under the control of Mr. Maubert and that the director Gonnessiat was providing seismograms readings that he circulated to ten European stations and printed out the seismograms in the “Bulletins mensuels du Bureau Central Météorologique” of the meteorological service. Actually, the meteorological observations were daily collected at the Algiers observatory (also called Bouzaréah observatory) and sent to the meteorological service, which was located at Algiers City Hall and linked to the observatory by an active telegraph (Boutequin 1911). The first seismic event reported in the earthquake catalogue as event recorded by the Bouzaréah station is the February 25, 1911 Aumale earthquake (Hée 1925). The first known seismogram available to us was recorded on August 25, 1922 during the Cavaignac earthquake and sent to the national press by Gonnessiat (Fig. 4). However, we know from the annual reports of the Commission inspection of the Algiers observatory that the Bouzaréah seismic station operated on a regular basis and constantly communicated with the “Bureau Central” of Strasbourg. This station was gradually supplemented by other stations distributed in northern Algeria to constitute the first seismic network of the country (see hereafter).

Fig. 4
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Seismogram of the August 25, 1922 Cavaignac earthquake

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We think that the 1906 San Francisco earthquake boosted the interest in seismology over the world at that time. In addition to the creation of the service of seismology by Gonessiat, we found in the literature (L’Afrique du Nord Illustrée of June 19, 1909) an article entitled “Earthquakes”, dealing with the necessity to reduce the disastrous effects of the earthquakes by using steel-reinforced concrete in constructing buildings. A picture of the first villa built with reinforced concrete in Algiers (Fig. 5) and a detailed description on the mode of construction are provided in that newspaper (see an extract in the original language in Appendix).

Fig. 5
figure 5

First building constructed with steel-reinforced concrete at Telemly (Algiers) in 1909 (L’Afrique du Nord illustré)

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3.10 1916: First Intensity Estimate?

We know that the first macroseismic scale which is the Egen scale was set up in 1828 according to Rothé (1925). The first attribution of an intensity estimate to a seismic event in Algeria, as communicated by the meteorological service to the national press, dates back to 1916 following the October 18 Algiers earthquake, for which an intensity VI on the Rossi scale is allocated (Echo d’Alger of October 19, 1916). However, one will see hereafter that the assessment of intensity started much earlier.

3.11 1919: Annals of the Institute of Earth Physics of Strasbourg

The year 1919 saw the appearance of “Annales de l’Institut de Physique du Globe de Strasbourg” (AIPGS), which are authored for Algeria by Hée from 1919 to 1939. Hée mainly based her work on the bulletins of Algiers observatory and its meteorological service. As mentioned above, the Algerian meteorological service was linked to the “Bureau Central” of Strasbourg, which belongs to the institute of earth physics. Hée’s lists of earthquakes are invaluable and comprise brief descriptions of the shocks, the date, origin time, intensity, and the name of the sites where each event was felt. This is therefore the first attempt at anything like a parametric catalogue of Algerian earthquakes. However, we note that except for some destructive events for which a detailed report is available, there is no information justifying the estimation of any intensity and there is seldom any attempt to determine the position of the epicenter. Despite these shortcomings, the annals of the institute of earth physics of Strasbourg remain invaluable. In addition to her contribution to these annals, Hée compiled three earthquake catalogues for Algeria. The first two catalogues by Hée (1925, 1933) start in 1911 to 1918, then merged with contemporary observations from 1919 to 1932 (already included in the AIPGS by Hée). The third catalogue by Hée (1950) went back to 1850, running forward to 1911. The materials used by Hée for this investigation are mainly the bulletins of the Algiers observatory, the bulletins of the Algerian meteorological service, and the press reports. We mentioned above that the first intensity estimate dates back to 1916. It seems that the observers of the Algerian meteorological service started assessing the intensity earlier since we found in Hée (1950) an intensity estimate for the August 23, 1904 Relizane earthquake. The main drawback of the Hée’s catalogues is the difficulty to attribute a location to the seismic event. Hée divided the Algerian territory into 19 quadrangles. There is any attempt to discover the relation between shocks felt at the same time at different places. One may find an earthquake that is reported at several quadrangles whenever it was felt at sites belonging to the different quadrangles. This seems to be the primary reason for which many of the subsequent authors ignored her invaluable work (Harbi et al. 2010).

3.12 1922: First Macroseismic and Instrumental Study and First Attempt of the Identification of the Causative Fault

The first damaging earthquake in history to be studied comprehensively both macroseismically and instrumentally by a contemporaneous author is the August 25, 1922 Cavaignac earthquake (AIPGS by Hée 1922). Based on press reports and accounts of anonymous observers of the Algiers observatory, Hée described the effects of that earthquake and allocated maximum intensity to 12 sites, without drawing an intensity map. Hée determined the instrumental epicenter using the seismograms of the following stations: Algiers, Cartuja-Granada, Barcelone, San Fernando, Coïmbra, Rome, Zurich, Strasbourg, and Helwan. It is also following the 1922 Cavaignac earthquake that Brives and Dalloni (1922) attempted to show the probable fault that generated the seismic event. However, the authors just described the geological structure of the affected region and made some correlations without presenting any illustration and/or evidence of the causative fault. They reported the hydrological effects caused by the earthquake, but nothing about the geological effects that one can often observe after the occurrence of a damaging earthquake (M 5.9, Aoudia and Meghraoui 1995), as it was the case for the aforementioned earthquakes. It seems that the study performed by Brives and Dalloni (1922) is based on their own knowledge of the geological structure of the region, not on fieldwork carried out after the occurrence of the earthquake.

3.13 1924 Questionnaires and First Isoseismal Map Drawn by a Contemporaneous Author

In a recent paper (Harbi et al. 2015), we said that the oldest questionnaire archived in the Center of Research in Astrophysics, Astronomy and Geophysics (CRAAG) dates back to 1954. It seems that the questionnaires, which were probably set up by the seismological service of the Algiers observatory or by the French institution to which that service was also affiliated, were used by Hée to perform the macroseismic study of the November 5, 1924 Douéra earthquake. This is also the first time where an isoseismal map was drawn and published (AIPGS by Hée 1924). Grandjean (1954) who used this kind of data sources in her work indicated that the dispatching of questionnaires by the IMPGA has spread after the Second World War. However, none of the questionnaires of the pre-1954 period exists in Algeria and we do not know if they are similar to the questionnaires available to us, and which were set up to be used according to the Rossi–Forel scale (see details in Harbi et al. 2017).

3.14 1925: First Map on the Earthquakes Frequency

In 1925, an anonymous author mapped the frequency of earthquakes of Algeria and Tunisia. This map showed the distribution in Algeria and Tunisia of areas with high, medium, and low earthquake frequencies (Ayadi and Bezzeghoud 2015).

3.15 1931: The Algerian Meteorological Service Became the “Institut de Météorologie et de Physique du Globe d’Algérie” (IMPGA)

The Institute of Meteorology and Earth Physics of Algeria was operating under the Algiers Faculty of Sciences until the end of the 1970s. Its main tasks, at its inception, were to carry out research in meteorology and geomagnetism while seismology remained at the Bouzaréah observatory, which was also affiliated to the Algiers Faculty of Science. It seems that seismology was undertaken at the Bouzaréah observatory till 1962. An astronomer who worked at the observatory from 1950 to 1962 informs us that the header of the official documents was labeled with three letters O.A.S, which correspond to “Observatoire d’Astronomie et de Sismologie” (Milet 1999). The Algiers observatory and IMPGA were liaising with the scientific agencies of North Africa and France, and were affiliated to the Council of the institutes and observatories of Earth Physics in France (Hubert 1932). Following the installation of the “Bureau Central International de Séismologie” at the institute of earth physics of Strasbourg (IPGS) in 1921 (Rothé 1983), the studies in earth physics including seismology were developed in the French colonies and the IMPGA was based on the model of IPGS. Joanny Lagrula, a geophysicist, was appointed as a new director of the Algiers observatory (1931–1938). The same year, M. Vesselovski was appointed as head of the seismological service and was in charge of the analysis of the seismograms. Lagrula wrote a document entitled “Rapport sur les travaux et la vie scientifique de l’Observatoire d’Alger” (report on the scientific works and life at the Algiers observatory, Lagrula 1931). Regarding seismology, Lagrula reported what follows: “Ladies Canovas and Feirar prepare the paper with black smoke (noir de fumée) and every month, M. Reiss prints a table of the measures read by M. Vesselovsky. Copies of these tables are regularly sent to the seismological observatories, particularly to the institute of earth physics of Strasbourg, which sends from its part its three-monthly bulletin. This bulletin is helpful for the final check of our seismograms, the original of which are often sent to the institute of Strasbourg upon their request” (translated from French).

3.16 1934: First Picture of the Seismograph of Bouzaréah

On September 7, 1934, a moderate damaging earthquake (M 5.1) struck Carnot in the Cheliff basin (Benouar 1994). As used by most of the directors of the Algiers observatory, Lagrula sent to the national press the information on this earthquake. Lagrula also sent to the newspaper “l’Echo d’Alger” a photograph of the Bosh-Mainka seismograph, installed at the Bouzaréah observatory (Fig. 6).

Fig. 6
figure 6

(photograph taken in 1934)

The Bosch-Mainka seismograph of the Bouzaréah observatory

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3.17 1935: Oued Fodda Seismic Station

After the installation of the first seismic station at Bouzaréah, a second one was installed in the Cheliff basin after the 1934 Carnot earthquake to monitor the induced seismicity near the Oued Fodda dam. This station operated until 1982 (see its characteristics in Bezzeghoud et al. 1994).

3.18 1948: Tamanrasset Seismic Station

The Tamanrasset station which is still in operation was installed in 1948 (Bezzeghoud et al. 1994) and was dedicated to teleseismic recording, thanks to its strategic position at a very quiet site. The data of this station have been already merged with data of other stations to study the anisotropy of northeast Africa (Hadiouche and Jobert 1988) and the anisotropic structure of the African upper mantle (Sebaï et al. 2006). The data of the Tamanrasset station were also recently used in studying the seismic activity in the Hoggar shield (Bourouis et al. 2013).

3.19 1949: The Algiers Seismic Station

A second seismic station (after that of Bouzaréah in the outskirts of Algiers) was installed in 1949 in the premises of IMPGA at Algiers University in the city center and operated until 1982. The Algiers station was equipped with two Coulomb-Grenet vertical seismographs, two horizontal seismographs and a Willmore vertical seismograph (Rothé 1970).

3.20 1950: First Mapping of the Causative Fault of an Earthquake, First Determination of Epicenter of Past Earthquakes and First Seismicity Map of Algeria

During the period March 13–18, 1949 upon the request of the General Government of Algeria and the “Centre National de la Recherche Scientifique (CNRS)”, Rothé (1950) investigated the M 4.9 Kherrata February 1949 earthquake, visiting and mapping the geology of the Babor mountains. Rothé benefited in this work from the expertise of the senior geologist Dalloni (see above for the 1922 seismic event) and the questionnaires of IMPGA already analyzed by Seltzer. This investigation was published in 1950 in Algeria in the bulletin of the “Service de la Carte Géologique de l’Algérie” along with two additional studies: (1) an overview on the seismicity of the Babor region and (2) a catalogue of the destructive earthquakes of Algeria (1716–1949) for which Rothé determined the epicenter in most of cases, and a seismicity map showing the distribution of the destructive earthquakes of Algeria. Grandjean who worked at the IMPGA until 1963 continued the work of Rothé (1950) and published in 1954 a quite similar catalogue for the earthquakes that occurred from 1940 to 1950. For many years until the 2000s, these catalogues remained the definitive account of historical Algerian earthquakes.

3.21 1955: Installation of the Relizane Seismic Station

This station operated until 1961 (Bezzeghoud et al. 1994). We know from the newspaper “l’Echo d’Oran” of December 19, 1959 that it recorded the December 12, 1959 Oran earthquake (I0 VII, Ms 4.5)

3.22 1958: Installation of the Setif Seismic Station

This station was equipped with a Coulomb-Grenet vertical short-period seismograph (Rothé 1970; Bezzeghoud et al. 1994).

There was also a seismic station located at Beni Abbes in the Sahara but we do not know when it was installed. Rothé (1970) informs us that the data of this station were handled by the French “Centre National de la Recherche Scientifique” (CNRS) and were sent to Algiers, then transmitted to Paris. We are also told that the Beni Abbes and the Tamanrasset stations were installed by the French for nuclear tests in the Hoggar and Sahara.

3.23 1960: First Analysis of the Seismicity of the Hoggar Shield

As mentioned above, the seismicity of Algeria is confined to the north of the country. To the south in the Hoggar shield (Tamanrasset region, Fig. 1), a seismic activity is also observed as already reported in Grandjean et al. (1960). Grandjean et al. revealed that 48 earthquakes (including nine aftershocks) were recorded between January 1, 1949 and December 31, 1958 by the seismological station of the Tamanrasset observatory (Fig. 7). About 70% of the recorded earthquakes have been located in the Silet area (SW of Tamanrasset) and would be linked to a recent volcanism according to Bordet (1952).

Fig. 7
figure 7

Histogram of the number of seismic events recorded in the Hoggar by the Tamanrasset station between January 1, 1949 and December 31, 1958. 67% of the earthquakes are located 50–100 km from Tamanrasset (Boughacha 2005, data are from Grandjean et al. 1960)

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4 Post-independence Period (1963–Today)

4.1 1963–1968: Research Activity of the IMPGA Under the Umbrella of Franco-Algerian Agreements

After the war of national liberation which lasted from 1954 to 1962, research activities in Algeria were carried out within the framework of an agreement (1963–1968) between Algeria and France. In this context, a council of the scientific research (CRS) was created. A second agreement signed for the period 1968–1971 led to the creation of the “Organisme de Coopération Scientifique” (OCS). During the period 1963–1971, CRS, then OCS handled the research activity of the Algerian institute of earth physics (Khelfaoui 2001). The seismological service of the IMPGA has continued its routine tasks regarding the determination of magnitude and epicenter of the earthquakes, which occurred during this period in Algeria. However, we noticed that the upturn of research activity has been somewhat slow at the beginning. For example, no attention was paid by the contemporaneous seismologists to the September 9, 1963 Bir Hadada destructive earthquake (M 5.7, Mokrane et al. 1994). This event was neglected in the subsequent catalogues and studies until the end of the 2000s when Harbi and Maouche (2009) reconstructed the macroseismic field of the Bir Hadada earthquake and estimated the epicentral intensity at VIII-IX EMS. It was not until 1966 that a first earthquake study appeared. This was related to the study of the January 1, 1965 M’sila earthquake (M 5.5, Grandjean et al. 1966). In this study, the authors attempted to use a multidisciplinary approach to analyze the 1965 event including macroseismology, tectonics, and gravimetric anomalies of the M’sila region. It was the first time when gravimetric data are integrated into a seismological study in Algeria.

4.2 1969–1970: Seismology in Algeria Faced Tough Times

This is what we learned from the mission report of Rothé (1970). Under the UNESCO/SC/1769/69, Rothé paid a visit to the seismological service of the IMPGA the December 5–9, 1969 to get inquired about the status of seismology in Algeria. He regrettably concluded that both macroseismic and microseismic surveys, which were before performed on a regular basis stopped, due to recruitment difficulties that IMPGA was facing at that time. We can confirm, as researchers working in the field of historical seismology and macroseismology in Algeria, that IMPGA stopped to disseminate questionnaires just before the independence in 1961, 1962, then in 1969 and 1970 after the end of the Franco-Algerian agreement. Benhallou who was physicist at IMPGA and affiliated to Algiers University where he had been teaching since 1961 (Bezzeghoud 2012) informed Rothé about the status of the seismic network that included the seismic stations mentioned above, most of them were operating in 1969. We are told that the seismological service planned to develop the seismic network and to acquire additional seismic stations, aiming at surveying the natural seismicity in northern Algeria and the induced seismicity in the vicinity of the dams of Oued Fodda, Meffrouch (Tlemcen region), Zerdaza (Skikda region), and near Biskra. During the mission of Rothé who was accompanied by Benhallou in the field, there were discussions about the necessity to (1) publish the macroseismic observations from 1951 onward (the last publication concerned the earthquakes prior to 1950 studied by Grandjean 1954), (2) update the map of maximum observed intensities, which was already prepared by Grandjean at IMPGA, and (3) develop the seismic network. These three important tasks constituted the first objective of the future head of the seismological service at IMPGA and future founder of the present Centre of Research of Astronomy, Astrophysics and Geophysics (CRAAG), Hadj Benhallou who met practical impediments in achieving results. We will see hereafter that the occurrence of destructive and damaging earthquakes in 1980, then in 1989 greatly contributed in realizing Benhallou’s ambitions.

4.3 1970–1979: Start of the Revival of Seismology in Algeria

In 1970, the ministry of high education and scientific research (MESRS) is created in Algeria. In 1971, the “Conseil Provisoire de la Recherche Scientifique” (CPRS) is created under the MESRS aegis and was replaced in 1973 by the “Office National de la Recherche Scientifique” (ONRS). Therefore, the IMPGA was affiliated to CPRS (Khelfaoui 2001), then to ONRS in December 1974. In the meanwhile, Benhallou was struggling for the revival of seismology in Algeria. Actually, after the Algeria independence, there was a drastic shortage of financial, material, and human resources. In addition, most of seismic data were generally moved to France. We noticed for example that even for the questionnaires left in Algeria and which cover the period 1954–1969, the questionnaires which are related to the strongest events, such as the 1954 Orléansville (M 6.7) and the 1959 Boumedfaa (M 5.6) earthquakes are lacking. Through thick and thin, Benhallou finally succeeded to publish the macroseismic catalogue of the Algerian earthquakes from 1951 to 1970. For the first time, this publication was edited by IMPGA (Benhallou et al. 1971). In 1972, Bockel (1972) who was a French consultant working at IMPGA published a second article first edited by the same institute, on the structure of the earth crust in Algeria using the seismic waves and determined a velocity model for Algeria. Roussel (1974) who was working at IMPGA and Algiers University presented a short note on the 1973 Mansoura earthquake. The resumption of the publications regarding Algeria seismicity materialized the revival of the IMPGA activities. Later on, Girardin et al. (1977) based on these last important papers (Benhallou et al. 1971; Bockel 1972) to relocate 80 earthquakes of the period 1950–1970 using P-wave arrival time of near-field stations (Algeria, Morocco, Spain, and Italy) and determine focal solutions for five events of the same period. This was the first time when focal mechanisms are calculated including Algerian data.

Geophysics with its various branches, such as seismology, geomagnetism, gravimetry, seismics, etc., started to be taught at the Department of Physics at Algiers University by the 1970s, while petroleum geophysics was taught at the “Institut National des Hydcrocarbures” since 1964 and at “Institut Algérien du Pétrole” since 1971, both at Boumerdes.

4.4 1980: Creation of CNAAG, El Asnam Earthquake the Largest Earthquake Ever Known in Algeria, Renaissance of Seismology in Algeria

In April 1980, the “Centre National d’Astronomie, Astrophysique et Géophysique” is created. Hadj Benhallou, the CNAAG founder, was appointed director of this center (1980–1998), which inherited from the Algiers Observatory and IMPGA. The headquarters of CNAAG, which is under the Ministry of High Education and Scientific Research, are based in the Bouzaréah Observatory. Macroseismic and microseismic surveys were continued by the technicians of CNAAG under the Benhallou supervision. Benhallou can be stated to have been the first Algerian seismologist who was involved in conducting microseismic and macroseismic surveys of recent events, in historical seismology, and in developing the local instrumental network. He was helped in this by the occurrence of the largest seismic event that Algeria had ever known, the 1980 El Asnam earthquake (M 7.5) and by the young researchers that Benhallou later on recruited at CRAAG (see hereafter).

Since the El Asnam earthquake, Algerian seismology has received a tremendous impetus. The CNAAG acquired the first portable network (MEQ 800), several studies of El Asnam earthquake were carried out in the framework of the Algero-French bilateral cooperation and many earth scientists from over the world visited the epicentral area and investigated the earthquake. These studies covered many subtopics of seismology and active tectonics including paleoseismological investigations and geodesy measurements, which were carried out for the first time in Algeria. This resulted in the publication of a collection of scientific papers (e.g., Ouyed et al. 1981, 1983; Deschamps et al. 1982; Yileding et al. 1981; Ruegg et al. 1982; Philip and Meghraoui 1983; King and Yielding 1984; Meghraoui et al. 1986, 1988a, b; Dimitrov et al. 1987, 1991 etc.) and the education of some postgraduate students who formed the first nucleus of Algerian seismologists. Up to now, the 1980 El Asnam earthquake, which can fairly be considered as a textbook case, continues capturing the scientists’ interest who are still working on many aspects related to this event (e.g., Roger et al. 2011; Bellalem et al. 2015).

4.5 1985–1989: Creation of the Department of Geophysics at USTHB, First Group of Geophysics Researchers at CRAAG

In February 1985, the CNAAG became a research center under the name “Centre de Recherche en Astronomie, Astrophysique et Géophysique” CRAAG. Another research center, with a role focusing on earthquake engineering, was created under the aegis of the Ministry of housing and urban planning in April 1985, the “Centre de Recherche Appliquée en Génie Sismique” (CGS). At the Algiers University which is the so-called “Université des Sciences et de la Technologie Houari Boumediène” (USTHB), a group of geophysicists created the Department of geophysics after receiving their degree of first post-graduation (in Algeria, for long time the first post-graduation degree corresponded to the so-called doctorate of third academic cycle or magister, whereas the second post-graduation corresponded to the doctorate or Ph.D.) and started to teach geophysics (fundamental and applied geophysics) to the first class of engineers in geophysics from 1986 onward. In 1987 after the 1985 Constantine earthquake (M 6.0), Benhallou, the director of CRAAG succeeded to get, from the government, a budget that allowed him to recruit the first core of geophysics researchers who had just defended their doctoral thesis in France.Footnote 1 A special tribute should be paid to Hadj Benhallou who spared no efforts in laying the foundations of a research center dealing with fundamental geophysics in Algeria. Benhallou took on the task of traveling to Paris (France) in order to meet six Ph.D. students who were preparing their defense thesis, and to convince them to return home and to helping him in driving geophysics forward at CRAAG. In the meanwhile he continued, until his death, to supervise the successive Ph.D. students in geophysics, particularly in seismology at the USTHB.

During this period, the earthquake studies were generally carried out by the CRAAG researchers or in the framework of local and international cooperation mainly between CRAAG, USTHB, and the traditional collaborators of the Algerian seismologists based in France. This was the case with the 1985 Constantine and Chenoua Mount 1989 earthquakes (M 6.0) (e.g., Bounif et al. 1987; Deschamps et al. 1991; Meghraoui 1991). The MEQ 800 portable visual recorders acquired after El Asnam earthquake were used in the investigation of the 1985 and 1989 earthquakes. In 1989, the first class of the engineers in geophysics of USTHB received their graduation degrees.

4.6 1990–2003: Inception of the Department of Seismological Studies and Survey, Installation of the First Modern Seismological Network, First Tomography Study, First Earthquake Catalogues in Independent Algeria

After the 1989 earthquake, which occurred in October at Chenoua mount near the Capital Algiers (Meghraoui 1991; Bounif et al. 2003), the installation of a modern seismological network was needed more than ever to increase understanding of the seismicity and seismotectonics of Algeria. CRAAG moved to the Ministry of Interior in April 1990. Right after, CRAAG received funding to install the first modern telemetered seismic network RSTA (Réseau Sismologique Télémétré Algérien). The funding for the acquisition of the Telemetred seismological network was done from Arab Fund for Economic and Social Development (AFESD). The Kinemetrics seismological network was shipped to Algiers and installed between 1989 and 1990 (personnal communication from Abdelhakim Ayadi, head of the seismic network from 1990 to 1998). In the meanwhile, things were beginning to take off for the ancient seismological service, which grew up and became “Department of seismological studies and survey”, which was constituted by important laboratories involved in modern and historical seismology, active deformation (geodetic measurements), seismotectonics, and paleoseismology. This department was created and headed by Mourad Bezzeghoud. The young researchers who just returned from France and joined CRAAG had started recruiting the engineers in geophysics and geology who were trained at the Algiers University (USTHB) and get them involved in several studies covering several aspects of fundamental geophysics. As mentioned above, the widespread interest that the 1980, 1985, and 1989 earthquakes generated was accompanied by a realization for the need to continue the work on the 1980 El Asnam earthquake regarding paleoseismicity and post-seismic deformation (Bezzeghoud et al. 1995; Meghraoui and Doumaz 1996; Lammali et al. 1997), to take interest in offshore seismicity and tectonics (Yelles-Chaouche 1991; Yelles-Chaouche et al. 1996), to get back to historical earthquakes through a multidisciplinary approach for a better understanding of the seismotectonics of the Tell Atlas (Aoudia and Meghraoui 1995), and above all to deploy a modern seismological network in the country.

The CRAAG which acquired and installed a modern Algerian Telemetred Seismological Network constituted of 32 short-period stations had the opportunity to study the Rouina (central Algeria) earthquake of January 19, 1992 (M 5.2), which was the first moderate seismic events recorded by this first telemetred network and studied by Bezzeghoud et al. (1994). Unfortunately, from 1992 to the beginning of the 2000s, the country experienced a bad security situation, which disrupted seismological research in Algeria. It was difficult to maintain the seismic stations distributed in isolated sites in Northern Algeria, most of them stopped, and few were lost or destroyed. This has not prevented the CRAAG researchers and their collaborators of USTHB to do what they could for keeping the flame of seismology alive in Algeria. As such, papers were devoted to the earthquakes that occurred during this decade of unstable security situation, which are the earthquakes of Mascara (1994, M 5.9, Benouar et al. 1994; Bezzeghoud and Buforn 1999; Ayadi et al. 2002), Algiers (1996, M 5.7, Maouche et al. 1998; Harbi et al. 2004), and Ain Temouchent (1999, M 5.8, Yelles-Chaouche et al. 2004).

As the political situation was getting increasingly unstable in Northern Algeria in the 1990s, the seismologists of CRAAG led an important project in southern Algeria, in the Hoggar shield, which is known as one of the most important swells in Africa. The objective was to explore the structure of the crust and upper mantle beneath the Hoggar swell and the Sahara basins through a teleseismic field experiment, which was carried out using a portable network of 33 seismic stations installed along a 700-km-long NNW–SSE profile running from Tamanrasset to In-Salah at north. This was the first time that teleseismic tomography is performed in Algeria with the collaboration of a French team from the CNRS and the University of Strasbourg (Ayadi et al. 2000).

In 1994, CRAAG published the first parametric earthquake catalogue of the whole Algeria (1365–1992) (Mokrane et al. 1994). This catalogue, which is the continuation of the earthquake catalogue of Algeria by Benhallou (1985), was compiled by young scientists under the direction of Mourad Bezzeghoud and Hadj Benhallou. The earthquakes included in this catalogue are mainly studied by means of questionnaires and instrumental data of IMPGA and CRAAG, and a macroseismic atlas is also provided. The same year, Benouar who was the PhD student of Ambraseys published a parametric catalogue for the seismicity that occurred in the Maghreb countries between 1900 and 1990 (Benouar 1994). Benouar reviewed the most important destructive events of Algeria through primary and secondary sources found in National and regional archives and relocated the instrumental earthquakes using the procedures of the international seismological center (ISC). Both catalogues (Mokrane et al. 1994; Benouar 1994) are still considered important guides for the knowledge of the seismic history of Algeria. In 1996, based on the first CRAAG earthquake catalogue, Bezzeghoud et al. (1996) mapped the maximum observed intensities of Algeria (1365–1989). This map was first published as a report for the Algerian National Insurance and Reinsurance Company (CAAR) and then as a scientific paper (Bezzeghoud et al. 1996). This map was updated until 2014 by Ayadi and Bezzeghoud (2015).

In 1998, Benhallou left the CRAAG and was then appointed dean of the “Faculté des Sciences de la Terre, de la Géographie et de l’Aménagement du Territoire” (FSTGAT, USTHB). Benhallou was replaced at CRAAG by Abdelkarim Yelles-Chaouche (1998–present) who, at that time, was the head of the Geophysics Department at CRAAG. Yelles-Chaouche published the second CRAAG earthquake catalogue (Yelles et al. 2002), which is the continuation of the catalogue by Mokrane et al. (1994), running forward to 2001, and particularly focused, with the technical staff at CRAAG that he supervised, on maintaining and restoring the seismic network. These efforts allowed increasing the number of operating seismic stations from 4 to 28 in 2000 and led to studying the Ain Temouchent earthquake of December 22, 1999 using Algerian data (Yelles-Chaouche et al. 2004). The second step toward the improvement of the Algerian seismic network consisted in its digitization and the acquisition of new seismic stations, among which mobile stations. These new acquisitions allowed performing comprehensive seismological studies of the second largest Algeria earthquake that occurred during the instrumental era (see the next section). The study of the Algerian margin for a better understanding of offshore seismicity and tectonics was one of the main objectives of Yelles-Chaouche who initiated in 2000 the MARADJA project with French partners (Domzig et al. 2006).

4.7 2003–Present: Seismology in Algeria, a Second Wind, New Motivations and Projects After the 2003 Zemmouri-Boumerdes Earthquake

It is commonly known that one learns more whenever a damaging seismic event occurs anywhere around the world. The progress in seismology owes much to the occurrence of earthquakes and we have seen throughout this article how true it is for Algeria. The security situation somewhat improved in Algeria when on May 21, 2003, a second strongest earthquake with magnitude 6.8 (after the 1980 El Asnam earthquake M 7.5) struck the region of Boumerdes, 50 km east of the Capital Algiers (Ayadi et al. 2003; Yelles-Chaouche et al. 2003). This seismic event, which had disastrous effects (Harbi et al. 2007b) mobilized the seismologists in Algeria, particularly the CRAAG newly trained scientists, and at international level (particularly from France, Turkey, Japan, Portugal, and USA). This was not just because of its size and its proximity to the Capital, but particularly to the tsunami that it triggered and the large coastal uplift of marine terraces that it induced, and which implied an important continental deformation related to an SE dipping and 55-km-long thrust fault (Meghraoui et al. 2004). This earthquake has been a subject of several studies covering many topics such as relocation of the main shock using the double difference model and the analysis of the aftershocks or the accelerometric record, teleseismic inversion, study of the coseismic and post-seismic deformation from GPS measurements, modeling the fault from geodetic and accelerograms, tsunami modeling, tomography, interferometric aperture radar, combination of gravity data and aftershocks sequence, stress transfer, earthquake engineering, macroseismology, etc. (Bounif et al. 2004; Delouis et al. 2004; Yelles et al. 2004; Semmane et al. 2005; Alasset et al. 2006; Laouami et al. 2006; Harbi et al. 2007b; Ayadi et al. 2008; Mahsas et al. 2008; Maouche et al. 2008; Belabbès et al. 2009; Sahal et al. 2009; Ouyed et al. 2011; Lin et al. 2011; Maouche et al. 2011; Cetin et al. 2012; Heidarzadeh and Satake 2013; Santos et al. 2014; Heddar et al. 2016; Kherroubi et al. 2017, etc.).

The 2003 earthquake did not just mobilize the scientists, but also funding of the Algeria Government. It was a good opportunity for the new director of the CRAAG, Yelles-Chaouche to upgrade the seismological network since the network installed in 1990 was in a bad state due to the difficulty of maintaining the seismic stations during the period of insecurity. The present ADSN network (Algerian Digital Seismic Network) has been developed on the former network RSTA, then updated. It consists of 20 broadband, 2 very broadband, and 47 short-period stations, and 21 accelerometers (for more details, see Yelles-Chaouche et al. 2013a). Refinements of the ADSN are continuously made toward an effective earthquake early-warning system (EEWS). From 2000 onward, precise instrumental data on earthquakes began to accumulate, and seismology has developed from the qualitative toward the quantitative side. Thanks to these improvements in recording continuously and steadily the events, the Algerian seismologists (mainly from CRAAG, CGS, and USTHB) started to systematically study recent earthquakes, such as the 2006 Laalam earthquake (M 5.2, Beldjoudi et al. 2009; Guemache et al. 2009; Bouhadad et al. 2010), the 2006 Tadjenna earthquake (M 5.0, Beldjoudi et al. 2011), the 2010 Béni Ilman earthquake (M 5.2, Yelles-Chaouche et al. 2013b; Abacha et al. 2014; Beldjoudi et al. 2016), the 2012 Béni Haoua earthquake (M 4.9, Abbès et al. 2016), the 2014 Bordj-Menaïel earthquake (M 4.1, Semmane et al. 2015), the 2013 Hammam Melouane earthquake (M 5.0, Yelles et al. 2017), the 2014 Algiers earthquake (M 5.3, Benfedda et al. 2017), the 2014 Mihoub earthquake (4.3, Semmane et al. 2017), etc.

As known, the 2003 Zemmouri earthquake triggered a tsunami (Alasset et al. 2006) that generated interest to Algerian scientists in exploring past tsunami (Maouche et al. 2008; Yelles-Chaouche et al. 2009; Harbi et al. 2011), tsunami deposits (Maouche et al. 2009), and studying tsunami risk (Amir et al. 2012, 2013, 2015; Amir and Theilen-Willige 2017) in Algeria. The study of tectonic activity of the Algerian margin was undertaken before and after the 2003 Zemmouri earthquake by two Algero-French collaborative projects, MARADJA and SPIRAL projects initiated by Yelles-Chaouche (https://spiral.oca.eu/), and resulted in a slew of papers (Yelles et al. 2009; Kherroubi et al. 2009; Bouyahiaoui et al. 2015; Hamai et al. 2015, etc.). The study of induced seismicity is also a topic that interested the Algerian seismologists and the first study was performed near the Beni Haroun dam (Semmane et al. 2012). The configuration of seismic stations and high quality of the collected data enable Algerian seismologists in using modern techniques in seismology at national, regional, and global scales (Radi et al. 2015, 2017; Haned et al. 2016; Kariche et al. 2017). The GPS technology is also currently used in Algeria by CRAAG and the GPS network REGAT (Réseau Géodésique de l’Atlas) with 60 GPS stations is collocated with the ADSN (Yelles-Chaouche et al. 2010). First results concerned the velocity field around the Ain Smara fault that was reactivated during the 1985 Constantine earthquake (Bellik et al. 2014). Reviewing the instrumental earthquakes for which a consistent database of seismic signals related to aftershocks is available is also a project carried out at CRAAG. Using new procedures, Ousadou et al. (2013) relocated the 1985 Constantine earthquake, and then they constructed a focal mechanisms database for the aftershocks of the 1985 Constantine, 1989 Chenoua Mount, 2003 Zemmouri, and 2004 Al-Hoceima (Morocco) earthquakes. This allowed them to calculate by inverting focal solutions the stress field and its variation along the northern part of the Maghreb area (Ousadou et al. 2014). This was the first time when focal mechanisms are calculated using Algerian data exclusively.

The development of quantitative seismology in Algeria did not mean that the qualitative seismology has been abandoned. To the contrary, the occurrence of the 2003 Zemmouri earthquake in a region not known before to have experienced such a destructive event had reinforced the belief that the best way to predict damage of future earthquakes is to explore past earthquakes of Algeria. In fact for many things in life, only the past is happening over and over again. It can be inferred from the above that the time range of reliable instrumental data is far too short when assessing seismic hazard for Algeria. Therefore, historical seismicity represents a wealth of potential information on long-term seismicity, which in its turn contributes to understanding seismotectonics and assessing seismic hazard. After 2003, there was a reawakening of interest in historical earthquake studies at CRAAG. Mining historical earthquake information with the aim to find out primary information sources is a time consuming and sometimes frustrating task, but very challenging for the historical seismology group created at the end of the 2010s at CRAAG. The group members are diligently constructing the Algerian earthquake archive. The macroseismic database still in development and available online reproduces verbatim historical accounts with references that permit verification and further work (see Harbi et al. 2015). The objective of the group is twofolds: (1) to improve the knowledge on the seismicity of Algeria and (2) to provide a credible input for seismic hazard assessment. Considering Ambraseys as a pioneer of the modern vision of historical seismology, the group is following the modus operandi which Ambraseys recommended in handling historical data and analyzing macroseismic information (Ambraseys et al. 1983; Ambraseys 2001). This cogent approach allowed obtaining efficient and reliable results. Nevertheless, the experience showed that the study of the historical earthquakes by the local scientists could give more sound results because they are more grounded in field reality. The historical earthquake research is becoming a matter of increasing returns in Algeria since it allowed us to go back further in time regarding the seismic history of Algeria (Ferdi and Harbi 2014). The acquisition of historical materials from a large variety of sources (Harbi et al. 2015) allowed intensity to be estimated/re-estimated for many events and isoseismal maps to be drawn/re-drawn, without forgetting to mention the newly discovered earthquakes, numbering today about 300 events only for eastern and a part of central Algeria (Sebaï and Bernard 2008; Harbi et al. 2015, 2017). As work continues for the rest of the country, this number will certainly be revised upward.

Besides the historical seismology group, seven other teams were created at CRAAG in quantitative seismology, earthquake warning, active deformation, seismotectonics, and seismic hazards and risk. The department of seismological studies and survey, which was created in the 90s, was developed and splitted into two divisions with eight research teams. After the period of late Hadj Benhallou who started almost from the scratch with very few resources to lay the foundations for the development of seismology in independent Algeria came the period of Abdelkarim Yelles-Chaouche with a modern strategy to strengthen and extend these foundations toward all the aspects related to earthquake science including the mitigation of seismic hazard and risk (for more details, see Yelles-Chaouche 2015). Both directors gained effective and whole-hearted support from the scientists and technicians involved in seismology, and the number of seismologists in Algeria is currently steadily increasing.

As mentioned above, efforts were made since the 1970s toward training and capacity building in geophysics. For now, a few dozen students defended their PhD thesis in seismology at USTHB. For long time, geophysics and/or earth physics were taught at Algiers and Boumerdes only. In 2005, an academic program devoted to earth physics including seismology has been initiated, with the help of CRAAG researchers, at Setif University (300 km east of Algiers), then at Khemis Miliana University (120 km west of Algiers) since 2015. Hence, one expects more scientists involved in seismology than before. The syllabus regarding seismology and related topics is quite the same in Setif and Khemis Miliana Universities and is inspired from the syllabus of USTHB (Algiers). It consists for the graduate students of plate tectonics and associated seismicity, faults, elasticity, propagation, seismometry, and source mechanism, while postgraduate students are involved in seismotectonic studies, interferometry, fault interaction, earthquake catalogues, aftershocks analysis, inversion, and very recently, active deformation (GPS), and historical seismology.

International conferences and symposia on seismology and related fields provided useful forums to discuss and spread the results obtained by Algerian earthquake scientists. CRAAG started this tradition during the Benhallou period in 1990 to commemorate the 1980 El Asnam earthquake and has continued in 1997 after the 1996 Ain Benian earthquake, and during the Yelles-Chaouche period in 2000 (on the Mediterranean seismicity), and on the occasion of the commemoration of the most significant Algeria earthquakes, which are the 1980 El Asnam earthquake (in 2010), the 2003 Zemmouri-Boumerdes earthquake (in 2013), and the 1985 Constantine earthquake (in 2015).

We shall not forget the continuous efforts of the regional science network The North-African Group for Earthquake and Tsunami studies (NAGET) and the Algerian academic association Société Algérienne de Géophysique (SAG) in disseminating the seismological information at regional and national level, and toward seismology in general. NAGET (http://naget.ictp.it), which was founded at the Abdus Salam International Centre for theoretical physics (ICTP, Trieste, Italy) in 2000, fosters and coordinates advanced research in earthquake science in North Africa through bilateral and/or multilateral projects by putting emphasize on interconnections within the group and maintaining joint links with the international scientific community. SAG (http://www.sag.dz), which was founded at USTHB in 2007, hosts the commission of seismology and natural risks, which aims at improving knowledge of the seismicity, seismic, and natural hazards of the country for a better risk mitigation.

5 Outlook

In this chapter, we wanted to share with the reader what we have learnt about the history of seismology in Algeria (see the timeline in Table 1) in our capacity of Algerian actors in the field of seismology. However, we believe that additional search in the archives of the institutions, which inherited from the Algiers observatory and the former IMPGA and, which are the CRAAG (Algiers) and especially the IPGS (Strasbourg), could provide substantial data related to many aspects of seismology in Algeria, such as the early seismograms (before 1922), the first stations and how they operated, the first questionnaires (before 1954), etc. Further archive search will allow filling some gaps and enriching the history of seismology presented here with respect to Algeria. This will be also a very good opportunity to perform a quantitative analysis of early seismograph recordings. This issue matters to us, but unfortunately most of early seismograms are lacking in Algeria and could be available at IPGS as we may infer from the present study (see above).

Several studies and projects lie ahead in terms of seismology in Algeria in addition to the projects, which had already been launched. A due contribution of the historical earthquakes to the seismic hazard assessment implies the estimation of their magnitudes on the basis of a robust method using generally intensity attenuation. The current work on historical seismicity of Algeria (Harbi et al. 2015) may increase the sample of the macroseismic data points on the basis of which a new intensity attenuation law could be derived. The calibration to the instrumental earthquakes may give good results especially if the intensity of all the earthquakes is objectively estimated according to a unique macroseismic scale. In the same way, the maximum calculated intensities (MCI) already mapped by Boughacha et al. (2004) could be updated. Algerian seismologists are currently taking a keen interest in induced seismicity and projects will be developed soon in this topic. A definite plan for a network in the Hoggar shield exists at CRAAG and USTHB to study and understand the mechanism of the seismicity of the region (Boughacha et al. 2006; Yelles-Chaouche 2015).

The reader certainly noticed that the history of seismology in Algeria is intertwined with the history of CRAAG and its father, the seismological service of the Algiers observatory and IMPGA to which the seismologists of the Algiers University were associated. After the Zemmouri–Boumerdes earthquake, the “Centre de Recherche Appliquée en Génie Sismique” (CGS) also developed seismological and accelerometric networks and its researchers published many valuable papers in earthquake engineering, which is, with seismic hazard and risk, outside the scope of the present paper. However, from last year onward, the CGS researchers started to perform earthquake studies (Abbès et al. 2016; Benfedda et al. 2017). The community of Algerian seismologists is growing up and this augurs well for the future of seismology in Algeria.

Last but not least, Algeria being an earthquake-prone country, raising awareness of living in a seismic country must be our first goal to reach. Therefore, it would be beneficial for the progress of seismology in the country and very challenging to attract students to earthquake science. The best way to achieve this, in addition to the awareness-raising campaigns on earthquakes that CRAAG takes in charge toward Algerian schools, is to introduce students to seismology through installing seismometers in schools. Our experience in teaching seismology to students showed us that they are more motivated when one allows them to have a close look to a seismic signal or damage caused by an earthquake that occurred in Algeria, or when we involve them in practical work, such as picking the P and S waves or training them in observational seismology (macroseismology and seismometry). They easily interact with real data. This concept produced successful results in the United Kingdom, USA, and Australia. Such a project permits connecting the school with research, higher education, and the world of the profession (monitoring). Algerian seismologists should draw on the experience of Australian seismologists for example (see Balfour et al. 2014 for more details) and, as such, will contribute to the risk assessment and its mitigation through education.