Liquefaction hazard mapping in the city of Boumerd\xe8s, Northern Algeria

Hamid Bourenane,Mohamed Tas,Youcef Bouhadad

doi:10.1007/s10064-017-1137-x

Abstract

The city of Boumerdès, located in Northern Algeria, was badly affected during the May 21, 2003 Zemmouri (Mw = 6.8) earthquake where extensive liquefaction has been reported. The aim of this paper is to assess and to map the liquefaction potential for Boumerdès. We collected and used data from 154 boreholes, 10 down-hole tests, 56 standard penetrations tests (SPT), and inventory of 35 water level points. This data has been analyzed in the framework of geographical information systems (GIS). We assessed the liquefaction potential index (LPI) by considering a seismic hazard scenario corresponding to amax = 0.48 g calculated, using a probabilistic approach, for a return period of 500 years. LPI values have been correlated to compile the liquefaction hazard map that indicates the quantitative characteristics of the liquefiable layers and the induced disruption probability area. Results show that the main part of the city of Boumerdès belongs to a low liquefaction potential area except for a narrow corridor along the Corso waterway, where the liquefaction potential is moderate to high. The obtained results are compatible with the geological, geotechnical and hydrogeological susceptibility to liquefaction of the area. The results also show a good agreement with the observations made after the May 21, 2003 Zemmouri earthquake. The obtained liquefaction hazard maps may serve as useful tools for land management and planning in the city of Boumerdès and as an example of liquefaction hazard assessment that may be applied in other populated cities in northern Algeria’s seismic prone areas.

Highlights

Earthquake-induced geological/geomorphological hazards in northern Algeria include several phenomena such as landslides, rock falls, and soil liquefaction (Bouhadad et al 2010; Bourenane et al 2014; Bourenane et al 2016)
We assessed the liquefaction potential index (LPI) by considering a seismic hazard scenario corresponding to amax = 0.48 g calculated, using a probabilistic approach, for a return period of 500 years
LPI values have been correlated to compile the liquefaction hazard map that indicates the quantitative characteristics of the liquefiable layers and the induced disruption probability area

Summary

Introduction

Earthquake-induced geological/geomorphological hazards in northern Algeria include several phenomena such as landslides, rock falls, and soil liquefaction (Bouhadad et al 2010; Bourenane et al 2014; Bourenane et al 2016). During the 2003 Zemmouri earthquake (Mw = 6.8) liquefaction induced ground deformation has been extensively observed in the most susceptible areas around Boumerdès city, mainly along riversides and along the beach land, where, the geological, geotechnical, and hydrogeological conditions are most favorable (Bouhadad et al 2004; Machane et al 2004). Worldwide, during the last few decades, liquefaction hazard zonation became among the first steps in each seismic risk analysis and mitigation strategy in urban areas. The liquefaction assessment has been conducted, by using field data obtained from boreholes, down-holes, and standard penetration tests, in terms of factor of safety against liquefaction (FS) and liquefaction potential index (LPI) For this purpose two main steps have been followed: (i) Geological, hydrogeological, geotechnical, geophysical, and seismic hazard data gathering (ii) assessment and mapping of liquefaction potential. The city is crossed by three rivers which are, respectively, Oued Boumerdès river in the east, Oued Tatareg river in the center, and the Oued Corso in the West (Fig. 2)

Methodology

50 À 10ðN1Þ60 þ

Findings

Discussions and conclusion