Ground-Motion Hazard Values for Northern Algeria

Abstract

This study examines distinctive features of ground motion parameters in northern Algeria. An initial computation of seismic hazard in terms of horizontal peak ground acceleration (PGA) and spectral acceleration (SA) at different periods, damped at 5%, is carried out for three different types of soils (rock, stiff soils and soft soils) for return periods of 100 and 475 years. In addition, uniform hazard spectra (UHS) are computed for these two return periods at several locations in the region. Then, the UHS computed for different soil types are proposed as a starting point to define elastic design spectra for building-code purposes. We have used the well-known Newmark-Hall approach. As proposed in the most recent International Building Codes, the SA (0.2 s) value is used to establish the spectral region for lower periods (region controlled by acceleration), whereas the SA (1.0 s) value is used to establish the spectral region for intermediate periods (region controlled by velocity). We also obtained important relations, dependent on site condition, between SA (0.2 s), SA (1.0 s) or SA max values, and the PGA, for both return periods of 100 and 475 years. Other relationships between PGA or SA max values have also been derived for return periods of 100 and 475 years, in this case independent of site condition.

Updated Probabilistic Seismic‐Hazard Values for Egypt

“…7). These relationships imply that mean PGA and SA max values of the UHS damped at 5% for a return period of 975 years (5% probability of exceedance in 50 years) in any location, are approximately 1.3 times those values for the same parameter for a return period of 475 years (10% probability of exceedance in 50 years), which coincides with Peláez et al (2006) and Hamdache et al (2012) results for northern Algeria. It appears as an important and interesting result independent of the used seismic-hazard approach and the considered GMPE.…”

“…Two relationships have been tried in the same way as those obtained for northern Algeria by Peláez et al (2006) and Hamdache et al (2012). The comparison between seismic-hazard values obtained for the same ground-motion parameter for return periods of 475 and 975 years provide clear linear relationships (Fig.…”

Using PS-InSAR with Sentinel-1 Images for Deformation Monitoring in Northeast Algeria

“…The Ain Smara Fault, shown in Figure 4, situated southeast of Constantine, is a major active fault and a primary source of earthquakes affecting Constantine confirmed by surface ruptures observed after the 1985 earthquake [35]. This fault can be considered as an important potential source of seismic activity according to the probabilistic seismic hazard study of Algeria [25]. It generated the strongest earthquakes in 1908, 1947, and in 1985, the latest corresponding to the strongest event recorded since the implementation of instrumental seismology in Algeria [35], causing significant damage in Constantine (Ms = 5.9, October 27, 1985).…”

“…It is also famous for its cultural heritage buildings, including constructions of architectural value, located at the Tellian Atlas. This is one of the regions most affected by earthquakes and slope deformations [21][22][23][24][25][26], which are the most important geohazards in the country.…”

“…As shown in Figure 3, the area of Constantine is characterized by a zone of detachment regimes. The tectonic context of the Constantine region results from the convergence of the Eurasian and African plates [21][22][23][24][25]. As a result, this region is one of the most seismically active regions of the Geosciences 2019, 9, 315 5 of 18 Mediterranean [33,34], characterized by intense seismic activity.…”