El Ouahabi et al. (2018) describe a sedimentary horizon at ~435 cm depth, located below a red clay layer, characterized by the presence of micro-sand dikes, indicating localized deformation within otherwise fine-grained deposits (El Ouahabi et al., 2018:5). The association with a red clay layer suggests deformation occurred within a relatively low-energy depositional environment, where fine sediments were subsequently disrupted by a sudden event.

The occurrence of micro-sand dikes is diagnostic of liquefaction, strongly supporting interpretation of this horizon as an earthquake-triggered deformation feature. Compared to E3, where deformation is more extensive and includes sand pillows, the 435 cm event appears more localized, suggesting either lower shaking intensity or greater distance from the causative rupture. Nevertheless, its formation within the tectonically active Amik basin implies a seismic origin rather than purely hydrological processes.

Chronologically, this event is constrained through the authors’ age–depth model, which integrates radiocarbon dating of micro-charcoal, sedimentation rates, and environmental correlations. Based on its depth within unit 2, the 435 cm horizon likely dates to the Iron Age, around 1000 BCE, though this estimate remains model-dependent and not tied to a specific historical earthquake.

Fig. 3b - Age–depth diagram for Amik Lake based on calibrated ¹⁴C age results obtained from micro-charcoal remains, ²¹⁰Pb and ¹³⁵Cs activities, correlation with other dated sedimentary sections in the Amik Basin, and historical earthquake tie point - click on image to open in a new tab - El Ouahabi et al. (2018)