engleski

ON EARTHQUAKE LOCATIONS USING THE SOURCE- SPECIFIC STATION CORRECTIONS IN THE KVARNER- VELEBIT REGION, CROATIA

Most of Croatian seismicity occurs in the Adria– Europe contact zone along the NE Adriatic coastal region. The Croatian Earthquake Catalogue lists today over 100.000 events which broadly outline the most active areas, but details are often blurred due to: a) insufficient density of local seismic stations, b) unfavourable station spatial distribution ; c) inadequate velocity models for the region ; d) onset-times picking errors ; and e) a complicated tectonic setting with many overlapping active faults. Here, we concentrate on the greater region of the Kvarner bay and Mt. Velebit (North-Eastern Adriatic), and investigate the influence of the first four parameters listed above. We use about 22000 events that occurred there since 1995, with over 250000 read phase onset times recorded by the local and regional networks, to create synthetic ‘ground-truth’ (GT) datasets with computed theoretical travel times for the phases actually observed for each event, assuming a simple realistic GT earth model and a range of picking-error normal distributions. These datasets are then used to locate the GT ‘events’ assuming a range of initial models, and utilizing standard location procedures that include several iterations of locations with source-specific station corrections and model adjustments. Such an approach allows us to statistically evaluate differences of each resulting set of locations from the GT- locations, and eventually draw conclusions about the systematic errors present in the catalogue due to each of the factors enumerated above. This study has been fully supported by the Croatian Science Foundation, grant IP-2014- 09-9666.

station geometry ; earthquake locations ; Kvarner-Velebit region ; Croatia

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