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  • Author or Editor: Duni Ll x
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Recently, significant efforts were attempted to the re-organization of the former network established in the early 80’s. As a result, sixteen digital accelerograph stations were installed most of them concentrated in seismic active, densely populated and industrialized areas. In fact, analog SMA-1 recorders were replaced by digital QDR-s upgrading thus network’s effectiveness. A number of accelerograms from small magnitude events have been recorded and data were properly processed in order to obtain the maximum ground motion parameters. Particular importance was devoted to the “band-pass” filter parameters in order to eliminate the noise that influences the spectral characteristics of the signal as well as the absolute values of maximum ground motion parameters in case of strong earthquakes.

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Compilation of a homogenous earthquake catalogue, by expressing the size of the earthquakes in a unified magnitude scale, is an important tool for the seismic hazard evaluation. The most reliable and useful scale of magnitude to be chosen as the common measure of earthquake size, for both historically known and the instrumentally recorded events, is the moment magnitude, M W . We investigate the empirical relationships between local magnitudes ( M L ) calculated by the seismological agencies operating in the Western Balkan countries, and the relevant moment magnitude M W , derived from the moment tensor analysis of medium-strong Western Balkan earthquakes. As result, regression relations converting M L to M W for these countries have been derived. Based on the proposed relations, an estimate of M W which can be considered as a unified magnitude scale can be calculated for each earthquake of the regional catalogue.

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A new probabilistic seismic hazard assessment for Albania is carried out using the smoothed gridded seismicity approach. Albania’s earthquake catalogue is already revised and expanded, covering a study area limited by 38 − 44.5°N Latitude and 18 − 24°E Longitude, and the time period from 58BC to 31/12/2008. The ground motion hazard map is presented over a 10 km grid in terms of peak ground acceleration for 10% probability of exceedance in 50 years, corresponding to 475-year return period. The reference site condition is firm rock, defined as having an average shear-wave velocity in the upper 30 m of the crust of 800 m/sec. It is the standard reference site condition used by the European seismic code (Eurocode 8) for seismic zonation and building codes. The main finding is that if this map is accepted as a reference indicator to establish a new regulatory national seismic zonation, design acceleration will be much higher than that applied in the current regulation. This implies that the competent authorities should take into consideration the obtained results to improve the existing design code in a more reliable and realistic basis in order to increase the safety level of constructions in the country.

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