Download Seismicity, seismic input and site effects in the Sahel

Seismicity, seismic input and site effects in the Sahel - Algiers region (North Algeria).
A. Harbi1,*, S. Maouche1, F. Vaccari3, A. Aoudia2, F. Oussadou1, G. F. Panza2,3 and D.
Benouar4
Abbreviated title: Earthquakes and seismic input modelling in Algiers area
Abstract
Algiers city is located in a seismogenic zone. To reduce the impact of seismic risk in
this Capital city, a realistic modelling of the seismic ground motion is conducted by using the
hybrid method that combines the finite differences method and the modal summation. For this
purpose, a complete database of geological, geophysical and earthquake data is constructed. A
critical re-appraisal of the seismicity of the zone [2.25°E-3.50°E, 36.50°N-37.00°N] is
performed and an earthquake list, for the period 1359-2002, is compiled. The analysis of
existing and newly retrieved macroseismic information allowed the definition of earthquake
parameters of macroseismic events for which a degree of reliability is assigned. Geological
cross sections have been built up to model the seismic ground motion in the city, caused by
the 1989 Mont-Chenoua and the 1924 Douéra earthquakes. Synthetic seismograms and
response spectral ratio is produced for Algiers, and they show that the soft sediments in
Algiers centre are responsible of the noticed amplification of the seismic ground motion.
1
Centre de Recherche en Astronomie, Astrophysique et Géophysique, BP. 63, Bouzaréah,
16340, Algiers, Algeria.
2
The Abdus Salam International Centre for Theoretical Physics, Earth System Physics
Section, Strada Costiera 11, 34014, Trieste, Italy.
3
Dipartimento di Scienze della Terra, Universita di Trieste, Via Weiss, 4, I-34127 Trieste
(Italy).
4
Built Environment Res. Lab. University of Bab Ezzouar (USTHB) Faculty of Civil
Engineering, BP 32 El-Alia/ Bab Ezzouar, Algiers 16111, Algeria
* Associate, The Abdus Salam International Centre for Theoretical Physics, Strada Costiera
11, 34014, Trieste, Italy. E-mail address: [email protected]