Site-Response Characteristics Evaluated from Strong Motion Records of the 2003 Boumerdes, Algeria, Earthquake

Abstract

Site response characteristics at seismic stations were investigated using horizontal-to-vertical (H/V) spectral ratios calculated from a seismic-motion dataset of the 2003 Boumerdes earthquake, and transfer functions were evaluated from soil profile data. Although high peak ground acceleration (PGA) values were recorded at some sites, the nonlinear effect at these stations was not clear. The H/V spectral ratios calculated from weak and strong motion events did not show a clear difference in the predominant period and amplitudes, and the shapes of the H/V ratios were flat for some stations. These observations are characteristic of the presence of firm to hard layers under the stations; however, one station was located on Quaternary deposits showed a remarkable amplification at the predominant period and a high PGA value.

Earthquake damage assessment: a theoretical framework and its application to Algerian buildings

“…The choice to use this record is due to the fact that the station is the closest to the area under study. The H/V spectral ratios [20] measurements performed by Meslem et al [21] show the existence of hard surface layers at Keddara station site. This argues for an absence of amplification.…”

The Effects of Building Characteristics and Site Conditions on the Damage Distribution in Boumerdès after the 2003 Algeria Earthquake

“…In addition to the Boumerdès station, the study looked at several other stations selected from different cities located along the fault trace. Details of the methodology used and the results obtained can be found in Meslem et al (2010).…”

“…But the main shock was soon followed by many aftershocks, which were mostly observed by the Boumerdès station ( Figure 1). Meslem et al (2010) on the impact of the local site effects on the values recorded by the Boumerdès station have shown the presence of firm deposits in the soil layers under the station. The resulting H/V spectral ratio curves from seismicmotion dataset of the 2003 Algeria earthquake showed insignificant shifts in amplitude for different levels of excitation.…”

“…Following the 21 May 2003, M w 6.8 Algeria earthquake (EERI 2003, Meslem et al 2010, the damage distribution observed by the survey mission in Boumerdès, the most severely affected city, showed that in some zones buildings were completely destroyed, while in other zones buildings with similar characteristics suffered only slight damage or none at all (Dunand et al 2004, Hellel et al 2010. Furthermore, in Boumerdès, which is characterized by rugged topography, field observations have noted increased damage to buildings, mostly to the mid-rise reinforced concrete (RC) moment-frame systems with four or five stories located on hilltops or close to the edges of steep slopes.…”

“…At position M13, which is the site of the seismic station, the shape of the H/V ratio curve is different to the shape computed from the seismic records; however, both computations show unclear-to-smoothed peaks. As mentioned earlier, the presence of firm deposits in the soil layers under the Boumerdès seismic station is assumed since the resulting H/V spectral ratio curves from the seismic-motion dataset of the 2003 Algeria earthquake showed insignificant shifts in amplitude for different levels of excitation (Meslem et al 2010). Only 600 m from the seismic station (Figure 6), the damage was very extensive; several RC buildings collapsed and others were heavily damaged.…”