Maximum parameters of ground motion derived from strong motion data in Albania

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

LOCAL RELATIONS FOR CONVERTING ML TO MW IN SOUTHERN-WESTERN BALKAN REGION

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, MW . We investigate the empirical relationships between local magnitudes (ML) calculated by the seismological agencies operating in the Western Balkan countries, and the relevant moment magnitude MW , derived from the moment tensor analysis of medium-strong Western Balkan earthquakes. As result, regression relations converting ML to MW for these countries have been derived. Based on the proposed relations, an estimate of MW which can be considered as a unified magnitude scale can be calculated for each earthquake of the regional catalogue

Probabilistic seismic hazard assessment of Albania

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

Seismic hazard assessment and site-dependent response spectra parameters of the current seismic design code in Albania

A probabilistically based hazard map of Albania expressed in terms of PGA for 475 years of return period following the spatially smoothed seismicity approach proposed by Frankel (1995) and developed by Slovenian researchers (Lapajne et al. 1997), is presented.  Taking advantage of this development, an effort has been made to analyze the parameters of site-dependent acceleration response spectra parameters of the current seismic design code KTP-N.2-89 in Albania

An updated and unified earthquake catalogue for the Western Balkan Region

The Harmonization of Seismic Hazard Maps in the Western Balkan Countries Project (BSHAP) was funded for 7 years by NATO-Science for Peace Program to support the preparation of new seismic hazard maps of the Western Balkan Region using modern scientific tools. One of the most important outputs of the BSHAP is an updated and unified BSHAP earthquake catalogue that is compiled directly from the datasets of earthquake data providers of the region. The BSHAP earthquake catalogue described here covers the geographic area limited by 38.0 degrees-47.5 degrees N, 12.5 degrees-24.5 degrees E and includes 26,118 earthquakes that occurred in the region between 510 BC and 2012. Details of data compilation efforts including the removal of duplicate events, unification of the magnitude scales, declustering of the catalogue and completeness analysis are presented in this manuscript. New magnitude conversion equations for various local magnitude scales of the data providers are developed with the aim of having homogeneous moment magnitude estimates. Completeness time intervals for the catalogue data are provided as inputs to the seismic source models used to obtain updated seismic hazard of Western Balkan Region. The unified and updated BSHAP catalogue is found to be compatible with the current well-established European and world-wide catalogues and represents a sound basis for analysis of the seismicity of this region