Evidence of seismites in coastal Quaternary deposits of western Oranie (northwestern Algeria)

Abstract

Coastal Quaternary deposits of western Oranie show typical soft-sediment deformations including sedimentary dykes, sand volcanoes, sismoslumps, thixotropic bowls, thixotropic wedges, diapir-like structures, and faults grading. Field observations indicate that these deformations exist at several levels of the studied deposits along the west Oranian coast. This study demonstrated that these structures are earthquakes-related, by analysis of potential trigger sources. Several arguments demonstrate the seismic origin: the depositional environment rich in water that located in an active tectonic region, the thixotropic nature of deformations and their large vertical and horizontal diffusion in the Quaternary series consistent with a seismic recurrence. This allows characterizing these Quaternary soft-sediment deformations as seismites that were triggered by earthquakes

Record of Late Neogene seismites in turbidite deposits of the Tafna Basin (NW Algeria)

“…Djedir) (Benzina, 2014). More over, the pres ence of seismites in the Qua ter nary ter race de pos its was pre vi ously noted in the Bieder, Ghazaouat and Terga ar eas (Boukhedimi et al, 2017).…”

“…The study area be longs to the Tafna Ba sin, in flu enced by the Al ge rian ac tive con ti nen tal mar gin. The lat ter is com monly re garded as a plate bound ary be tween Af rica and Eur asia, and cor re sponds to a seis mi cally-ac tive con ver gent zone (Boukhedimi et al, 2017). Fur ther more, late Neo gene (Mio cene) sed imen ta tion in the Tafna Ba sin was dom i nated by both extensional (Serravallian-Lower Tortonian) and compressional (upper Tortonian-Messinian) tec ton ics (Glangeaud, 1951;Dubourdieu, 1962;Andrieux, 1971) fol lowed by vol ca nic ac tiv ity dur ing the late Mio cene (Megartsi, 1985).…”

“…This in ter val of seis mic ac tiv ity was fol lowed by vol ca nic (rhyolitic) ac tiv ity from the late Mio cene at ~14 Ma (Megartsi, 1985). Boukhedimi et al (2017) and Guessoum et al (2018), in their stud ies of the coastal Qua ter nary de pos its from NW Al geria, in di cated seis mic ac tiv ity dur ing this pe riod.…”

Lower Cretaceous clastic dykes in southern Tibet: Characteristics and palaeogeographic significance

“…Clastic dykes are generally regarded as a soft‐sedimentdeformation structures (Boukhedimi et al, 2017; Moretti & Sabato, 2007). In the studied area, other soft‐sedimentdeformation structures were encountered in the underlying volcaniclastic sandstones, such as sand pillows and convolute bedding (Figure 3a,d).…”

Coastal Environmental Impact of Geohazards in the Area of the Habibas Islands (Western Algeria, Alboran): Insights from GIS-Analysis and Remote Sensing

“…Hence, when strong shaking, even in the context of normal and strike-slip faulting, sediments can be remobilized and provide a triggering factor for local tsunamis offshore. Moreover, seismites have as well been evidenced in western Oranie and the large distribution of the observed deformations within western Oranie (100 km of coastline) suggests a strong source of energy [29], [52]. Finally, the 2016 Alboran seismic sequence with the first shock of magnitude reminds the potential for strong earthquakes in the region with a well-demonstrated threat for tsunami waves reaching the western coast of Algeria not only for thrusting events but for strike-slipping motions as well [16], [53].…”