Can plate motion surveys by GPS measurement be considered as an alert system for earthquake occurrence?

Abdelhakim Ayadi
CRAAG, BP 63, Bouzaréah 16340 Algiers, Algeria.
Tel. /Fax: +2 13- 2-90 14 24,
E-mail: ess1@ist.cerist.dz

Seismic phenomena are among the most important sources of damage and loss of life in Algeria (for example: Algiers in 1716, Io=X, 20,000 dead; Blida in 1825, Io=X, 7,000 dead; El Asnam in 1980, Io=IX, 2633 dead; Tipasa in 1989, Io=VIII, 22 dead; Mascara in 1994, Io=VIII, 171 dead).

The seismic survey at CRAAG is in charge of a telemetered seismological network since 1990. A set of 32 stations is spread along the Atlas Tellian region, considered as the most active zone in northern Algeria. We propose to install a permanent GPS (Global Positioning System) network along the Tellian Atlas (northern Algeria), in order to monitor the displacement of the African plate. We think that the variations in velocity and deformation fields of the plate, deduced by the GPS survey, will enable us to locate the zones where a probable stress drop could occur. These observations must be made on a long-term basis in order to perform a better survey. We are in the first phase of the project which consists of choosing the sites where GPS receivers will be installed. The survey itself will begin by the end of 1998.