Field evidence of Quaternary seismites in the Mostaganem-Relizane (western Algeria) region: seismotectonic implication
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ORIGINAL PAPER
Field evidence of Quaternary seismites in the Mostaganem-Relizane (western Algeria) region: seismotectonic implication Nabila Guessoum 1
&
Azzeddine A. Benhamouche 1 & Youcef Bouhadad 1 & Hamid Bourenane 1 & Moustafa Abbouda 1
Received: 2 January 2018 / Accepted: 15 October 2018 / Published online: 24 October 2018 # Saudi Society for Geosciences 2018
Abstract Northwestern Algeria, Tell Atlas chain, belongs to the converging Africa-Eurasia plate boundary. Several active faults have been previously identified and several earthquakes occurred in the past. In the present study, seismites are observed in the Quaternary deposits. The identified seismites include injection sand dykes, pillar structures, pillow structures, load-cast structures, water escape structures, sismoslumps, thixotropic wedges, and thixotropic bowls. The following arguments support their seismic origin: (i) presence of active faults able of producing strong earthquakes, (ii) the granulometric characteristics of the deposits are favorable to liquefaction, (iii) the observed features, mainly those related to water escape structures, are comparable to those observed in modern earthquakes. Therefore, such features are evidence of the occurrence of earthquakes of M > 5.5 magnitude in this study area, which may occur in the future. Keywords Seismites . Quaternary deposits . Liquefaction . Active faults . Earthquake . Algeria
Introduction Seismites are soft-sediment deformation structures (SSDS) induced by seismic shocks (Seilacher 1969), in recent, not yet compacted deposits (Plaziat and Ahmamou 1998; Montenat et al. 2007; Owen and Moretti 2008; Ezquerro et al. 2015). In some cases, these deformations may also affect the hardened rocks by means of hydro-fracturing (Montenat et al. 2007). Seismites can be found in different geological ages; nevertheless, Quaternary seismites are interesting to study because they can be used in seismic hazard studies (Sims 1975; Obermeier et al. 1985; Obermeier 1996; Marcos et al. 1996; Mc Calpin and Nelson 1996; Hibsch et al. 1997; Bowman et al. 2001; Ken-Tor et al. 2001; Jewell and Ettensohn 2004; Owen and M o r e t t i 20 11; O w e n e t a l . 20 11) . I n A l g e r i a ,
* Nabila Guessoum [email protected] 1
National Center of Applied Research in Earthquake Engineering (CGS), Rue Kaddour Rahim prolongée, BP. 252, 16040 Hussein Dey, Algiers, Algeria
liquefaction features were reported for the historical Djidjeli earthquake of 1856 (Mokrane et al. 1994; Harbi et al. 2011) and were observed during the El Asnam 1980 earthquake (surface wave magnitude, Ms = 7.3) and the Zemmouri 2003 earthquake (moment magnitude, Mw = 6.8) (Philip and Meghraoui 1983; Bouhadad et al. 2004; Bouhadad 2007). Study of seismites in Algeria is relatively recent. In the Algiers region, Djediat et al. (1995, 2011) described seismites in the Tyrrhenian marine terrace deposits. Bouhadad et al. (2009) observed Holocene liquefaction-induced features in the epicentral area of the Zemmouri earthquake (Mw = 6.8) occurred on
