Preliminary Estimation of Kappa Parameter in Croatia

Spectral parameter kappa is used to describe spectral amplitude decay “crash syndrome” at high frequencies. The purpose of this research is to estimate spectral parameter kappa for the first time in Croatia based on small and moderate earthquakes. Recordings of local earthquakes with magnitudes higher than 3, epicentre distances less than 150 km, and focal depths less than 30 km from seismological stations in Croatia are used. The value of kappa was estimated from the acceleration amplitude spectrum of shear waves from the slope of the highfrequency part where the spectrum starts to decay rapidly to a noise floor. Kappa models as a function of a site and distance were derived from a standard linear regression of kappa-distance dependence. Site kappa was determined from the extrapolation of the regression line to a zero distance. The preliminary results of site kappa across Croatia are promising. In this research, these results are compared with local site condition parameters for each station, e.g. shear wave velocity in the upper 30 m from geophysical measurements and with existing global shear wave velocity – site kappa values. Spatial distribution of individual kappa’s is compared with the azimuthal distribution of earthquake epicentres. These results are significant for a couple of reasons: to extend the knowledge of the attenuation of near-surface crust layers of the Dinarides and to provide additional information on the local earthquake parameters for updating seismic hazard maps of studied area. Site kappa can be used in the re-creation, and re-calibration of attenuation of peak horizontal and/or vertical acceleration in the Dinarides area since information on the local site conditions were not included in the previous studies

Crustal and uppermost mantle structure beneath the External Dinarides, Croatia, determined from teleseismic receiver functions

Broad-band seismograms of teleseismic events recorded at the Croatian Seismological Network were used to compute radial receiver functions (RFs) for eight locations in the External Dinarides. Waveform modelling was performed by a multistep matching of the theoretical RFs computed for horizontally layered 1-D isotropic models with the averaged observed RFs. Constraints from existing deep seismic sounding profiles, traveltime curves of regional crustal seismic phases and intuitive inferences gained from interactive forward modelling were used to construct initial 1-D models of the Earth. A non-linear inversion was performed in two steps-a grid search followed by the Monte Carlo search for the model parameters. Concurrently, RFs from different azimuths were stacked to obtain trade-off estimates of crustal thickness versus Vp/Vs ratios. The Moho depths were found in the range from around 40 km for Northern Adriatic stations to over 55 km for stations in the central part of the External Dinarides. Comparing our results with recent maps of the Moho topography inferred from seismic and gravimetric data, we find that for some stations the agreement between our results and the existing Moho maps is very good. For the others, we find the Mohorovičić discontinuity to be considerably deeper, indicating some of the thickest crust in Europe. Although it is plausible that such a deep Moho could be a consequence of a complex tectonic setting of the region (e.g. overlapping of two large tectonic units-the Adriatic microplate and the Dinarides), this result will have to be verified in the future studies using various other geophysical techniques

Harmonization of the Seismic Hazard Maps of the Western Balkan Region Project Earthquake Catalogue and Strong Ground Motion Database

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 earthquakee catalogue describedd here covers the geographic area limited by N, E and includes 26,118 earthquakes that occurred in the region between 510 BC and Details of data compilation efforts including the removal of duplicate events, unificationn of the magnitude scales, declustering of the catalogue and completeness analysis are presented in Markusic et al. (2015). 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 updatedd seismic hazard of Western Balkan Region. The unified and updated BSHAP catalogue is found to be compatible with the current wellanalysis established European and world-wide catalogues and represents a sound basis for of the seismicity of this region. In the framework of both BSHAP-1 (Akkar et al. 2011) and BSHAP-2 (Gulerce et al. 2015) regional projects, strengthening of the regional free field strong motion network capacity and harmonization of strong motion data base, among others, were one of the primary project goals and achievements. Harmonized strong motion data base has established a solid base for proper selection of ground motion prediction equations (GMPEs) for probabilistic seismic hazard assessment by comparing the compiled strong ground motion dataa with the available global, European, Euro-Med, and regional ground motion prediction models. BSHAP partner countries encourages the use of collected free field strong ground motion database for the end users and international earthquake research communities by realizing improved multi- lateral data exchange protocols and publishing the major project findings

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

Harmonized Seismic Hazard Maps for the Western Balkan Countries

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. In the framework of BSHAP, the regional free field strong motion network capacity was increased significantly by the purchased and installed recorders and the BSHAP strong motion database that includes both pre-BSHAP (mostly analog) and post-BSHAP (all digital) recordings was compiled. The BSHAP strong motion database is used for proper selection of the ground motion prediction equations (GMPEs) for the probabilistic seismic hazard assessment (PSHA) by comparing the compiled strong ground motions with the predictions of candidate global, European, and Euro-Med GMPEs in a systematic manner. BSHAP collected relevant knowledg

BSHAP project strong ground motion database and selection of suitable ground motion models 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 and Security Program to support the preparation of new seismic hazard maps of the Western Balkan Region. In the framework of BSHAP, the regional free field strong motion network capacity was significantly increased by deployed recorders (Gulerce et al. in Final report of improvements in the Harmonized Seismic Hazard Maps for the Western Balkan Countries (BSHAP-2) Project, NATO SfP-984374. http://wbalkanscimicmaps.org, 2015) and the BSHAP strong motion database that includes both pre-BSHAP (mostly analogue) and post-BSHAP (all digital) recordings was compiled. The BSHAP strong motion database includes uniformly processed strong motions along with the related earthquake metadata and station information; therefore, it provides a solid base for the ground motion characterization studies in the region. The established database is used for selection of the ground motion prediction equations (GMPEs) to be employed in the probabilistic seismic hazard assessment by comparing the compiled strong ground motions with the predictions of candidate global and Euro-Mediterranean GMPEs in a systematic manner. Details of the selection strategy including the analysis of model predictions for ground motion scaling, data testing to evaluate the model performance, and ranking is provided here along with the GMPE logic tree used in the proposed seismic hazard maps by Kuka et al. (Bull Earthq Eng, under review)

Reply to "Comment to BSHAP project strong ground motion database and selection of suitable ground motion models for the Western Balkan Region" by Carlo Cauzzi and Ezio Faccioli

This article is reply to the comment sent by Carlo Cauzzi and Ezio Faccioli related to the published article "BSHAP project strong ground motion database and selection of suitable ground motion models for the Western Balkan Region" by Salic et al. (2016)

Reply to “Comment to BSHAP project strong ground motion database and selection of suitable ground motion models for the Western Balkan Region” by Carlo Cauzzi and Ezio Faccioli

This article is reply to the comment sent by Carlo Cauzzi and Ezio Faccioli related to the published article "BSHAP project strong ground motion database and selection of suitable ground motion models for the Western Balkan Region" by Salic et al. (2016)