Application of Automated Throw Backstripping Method to Characterize Recent Faulting Activity Migration in the Al Hoceima Bay (Northeast Morocco): Geodynamic Implications

Automation of the throw backstripping method has proven to be an effective tool for the determination of the evolution of tectonic activity in wide fault zones. This method has been applied to the Al Hoceima Bay (southwesternmost Mediterranean, Alboran Sea) for a time period covering the last 280 kyr on 672 faults imaged on 265 high-resolution seismic reflection profiles. This area was affected by major earthquakes and corresponds to a transtensional basin deformed by growth faults. The automated application of throw backstripping allowed for a faster deciphering of the migration of tectonic activity. Results show a westward migration of the deformation with quickly increasing deformation rates in the most recent time frames near Al Hoceima, one of the most populated cities. This migration is in agreement with the current seismicity, the GPS data, and recent brittle deformation data. Vertical throw rates of up to 0.47 mm/year have been calculated, for the most recent time periods, in segments of the Bokkoya fault zone. The westward migration of the deformation fits with the reconstruction suggested by the westernmost Mediterranean geodynamic models during the Pleistocene epoch, and it might be the consequence of the interaction between the northwest (NW) movement of the South Alboran indenter and the back Rif south-westward displacement. The highly accurate constraints of the evolution of the tectonic activity offered by this automation will substantially improve the seismic hazard assessment.

Seismic analysis of bridges with non-linear soil-structure interaction

This study is concerned to the investigation of the stability of bridges by taking into account the soil structure interaction and their impact on the dynamic behavior of the structures. The bridge studied is localized at PK 318 + 750 at the national level, between the city of Al Hoceima and Kasseta (Morocco). The analyses are carried out with the ANSYS code demonstrated that for conditions of support, the distribution of displacements and the fundamental frequency for each type of soil change according to its mechanical properties. This work also indicates that the proximity of the fundamental frequencies of the soil structure and strongly influences the soil-structure interaction.

Numerical Analysis of Twin Tunnels Lining under Different Seismic Conditions

The last seismic events showed that tunnel lining may suffer extensive damage. Employing numerical modeling has a great importance in predicting the seismic performance of tunnels. This paper tests the tunnel lining of the Zaouit Ait Mellal (ZAM) twin tunnels located between the cities of Marrakesh and Agadir in Morocco. Dynamic analysis was adopted by FLAC 2D software using the finite-difference elements. Four soil cross-sections were chosen, with different support devices installed along the twin tunnels, such as rock bolts and steel ribs. The seismic signals introduced as input were obtained from three different earthquakes: Al Hoceima 2004 in Morocco, EL Centro 1940 in the USA, and Kobe 1995 in Japan. The numerical results show that the deformation of the tunnel lining is more noteworthy in the sections using steel ribs compared to those using rock bolts, which is observed by the large values of relative displacement, reaching 1020 (mm) and 2.29 × 105 (N.m/m) of maximum bending moment. The analysis indicates that these sections present higher vulnerability during an earthquake, which should be considered when looking at the overall safety of the tunnel.

Bioaccumulation and health risk assessment of trace elements in Mytilus galloprovincialis as sea food in the Al Hoceima coasts (Morocco)

The monthly variations in metal concentration of Cadmium (Cd), Zinc (Zn) and Chromium (Cr) were determined in tissues of Mytilus galloprovincialis and seawater obtained from the mussel farm installed along the Al Hoceima coasts, during the sampling period of 2018. The heavy metals encountered in the bivalves were higher than those observed in their environment with a decreasing order of Zn > Cr > Cd. The results also showed a decreasing trend for the metals studied during the summer sampling campaign. The maximum values were obtained during the wet periods. The monthly variations in trace metals observed in the mussel tissues were due to environmental parameters and the physiological state of the bivalves. Our results revealed that the average concentrations of pollutants found in M. galloprovincialis were below the limits allowed by the Food and Agriculture Organization of the United Nations (FAO) which are 2.0, 1000 and 1.0 mg/kg, for Cd, Zn and Cr, respectively in molluscan shellfish for human consumption. Therefore, the trace elements present in the tissues of Al Hoceima shore mussels do not represent a risk to human health associated with their consumption, even during the period of their maximum bioaccumulation. Our work highlights the potential use of Mytilus galloprovincialis in the Biomonitoring of metallic pollutants in this region of the northern Moroccan coasts.

Estimating completeness of foodborne disease registration in North West Morocco

This study aims to estimate the total number of poisoning cases and completeness of foodborne disease surveillance in the region of Tanger-Tétouan-Al Hoceima in North West Morocco. This retrospective study was conducted to assess the completeness of food poisoning surveillance system in the Tanger-Tétouan-Al Hoceima region over a three-year period from January 1, 2014 to December 31, 2016. The data used for this study were obtained from two sources, including the national poisoning database of the Moroccan Poison Control Center (MPCC) and provincial hospital registries in the study area. The completeness of foodborne disease reporting was estimated using the capture-recapture method. During the study period, 235 cases of foodborne diseases were reported to the Moroccan Poison Control Center, 725 cases were notified to the provincial hospital registries and 98 cases were common to both sources. The estimated total number of poisoning cases was 1,739 (95% CI: 1,494-1,983). The completeness of foodborne disease surveillance for the national database of poisoning and hospital registries was estimated to be 13.5% and 41.7%, respectively. Improvement of the completeness of poisoning surveillance system is needed to estimate the true incidence of poisoning in Morocco.