In the year of 1904, in the region of Krupnik–Kresna occurred one of the strongest earthquakes on the Balkan Peninsula, felt in almost whole Eastern Europe. The magnitude of this event was about 7.5 and intensity X in Medvedev-Sponheuer-Karnik scale in the epicentric zone. The seismologically active structure which caused this destructive event is the Krupnik Fault – a part of the Struma fault zone.
In the framework of “Young scientists” project between several research institutions in Bulgaria, an attempt to compare and complete the data, results and conclusions from different methods of geodesy, gravimetry and seismology was made. The main goal is to form a whole geodynamic picture in the area of investigation. Part of the present work is to determine double couple focal mechanism solutions from P wave first motion polarities of small earthquakes with magnitude about 3 in the region. On the other hand, several GPS campaigns were carried out re-measuring the points from long-existing investigation network in the area. A new set of benchmarks was established for levelling profiles through the visible rupture remaining after the strike from 1904. Also two gravimetric profiles crossing the main tectonic structures were re-measured. All these studies confirm the recent activity of the Krupnik fault.