Abstract
Abstract. Seismic monitoring in Algeria has seen great changes since the Boumerdes earthquake of 21 May 2003. Indeed, the installation of a new digital seismic network has resulted in a significant upgrade of the previous analog telemetry network. During the last four years, the number of stations in operation has increased substantially from 25 to 69, and 20 of these are broadband, 2 are very broadband, 47 are short period. 21 are equipped with accelerometers. They are all managed by Antelope software from Kinemetrics (US Cie), and they are all connected in real time and use various modes of transmission (e.g., satellite, internet, mobile phone). The spatial repartition of the stations now cover most of northern Algeria. In addition, 70 GPS stations have recently been added to this seismological network, most of them collocated with the seismological stations. Since the installation of the network, the records of local or distant events have improved significantly. The automatic processing of the data in a few minutes allows alert messages to be distributed to Civil Defense and other national authorities to react promptly to any emergency. The current strategy is to improve the data quality, to increase the density of the network by adding about 50 new stations, to reduce the processing time, and to reduce the time needed to send out an alert message. The result should be greatly improved network performance, which will lead to an effective early-warning system.
Highlights
Northern Algeria lies along the Eurasian-African tectonic boundary
The spatial repartition of the stations cover most of northern Algeria
Some seismic events in the southern part of Algeria, inside the Hoggar shield, have been recorded for the first time by the network, and this demonstrates the seismic character of that region, previously thought to be aseismic
Summary
Northern Algeria lies along the Eurasian-African tectonic boundary. In contrast to other Mediterranean areas (e.g., Italy, Greece, Turkey), Algeria is generally marked by moderate rather than strong seismic activity (Fig. 1) (Benhallou, 1985; Yelles-Chaouche et al, 2006). Developments in seismological technology, in terms of sensors, digitizers, and communication networks, have led to the installation of new alert systems in several countries as Japan (Nakamura, 1996), USA (Allen, 2007), Turkey (Erdik et al, 2003). The purpose of these systems is to provide, as quickly as possible, the first parameters of the event, to rapidly inform the decision makers for crisis management, and to enable strategic infrastructure to be safeguarded, such as nuclear power plants and railways. The second objective now is to install sufficient numbers of new seismological stations so that the territory will be covered more densely, to improve data transmission, and to establish an early warning system
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