Dva dana prije potresa u Drežnici 2013. godine došlo je do kompresije terena ; Two Days before the Earthquake in Drežnica 2013 there has been the Compression of the Terrain

U radu su analizirane promjene duljina stranica između GNSS -postaja u CROPOS-u i promjene njihovih visina prije, za vrijeme i nakon potresa u Drežnici 2013. godine. Potres s epicentrom u Drežnici bio je mali (lagani) potres magnitude 4,6. To je bio jedan od najvećih potresa u Hrvatskoj od 2008. godine, kad je postavljena mreža stalnih GNSS-postaja. Zato smo odlučili utvrditi koliki su bili pomaci terena i da li se eventualno vidi prethodni GNSS-signal prije potresa te koliki su pomaci terena nakon potresa. Iz mjerenja se vidjelo da se obala u Senju prije potresa u Drežnici uzdizala u vremenu od dvadesetak dana i da će vjerojatno doći do potresa. Osim toga uočeno je da je dva dana prije potresa u Drežnici došlo do kompresije terena, koja je bila mala jer je potres koji je slijedio bio male magnitude. Do isto takvih rezultata došlo se pri analizi permanentnih GNSS-mjerenja u Kraljevu (Solarić, N. i Solarić, M. 2012), a i za potresa u Skoplju 2016. koji se još analizira. Ta istraživanja pokazuju da u Hrvatskoj ima smisla organizirati posebnu službu u CROPOS-u koja će pratiti promjene Zemljine kore u područjima s jačom seizmičkom aktivnošću. To se odnosi na područja s većim brojem stanovnika kao što je Zagreb, područje oko nuklearke Krško, Dubrovnika, Splita i Rijeke. Sve to može pomoći seizmotektoničarima da mogu eventualno uz druge geofizičke i nove satelitske metode (na primjer TwinSat) (URL 4, URL 5, URL 6) sigurnije najaviti mogućnost potresa. ; The changes of side lengths between GNSS stations in CROPOS and the changes of their heights before, during and after the earthquake in Drežnica in 2013 are analysed in this paper. The earthquake with the epicentre in Drežnica was a small (slight) earthquake with the magnitude 4.6. It was one of the biggest earthquakes in Croatia ever since 2008 as the network of permanent GNSS stations was established. We have therefore decided to determine the size of terrain movements and whether previous GNSS signal could be noticed before the earthquake, and also the size of terrain movements after the earthquake. The measurements indicated that the coast in Senj was uplifted in the time of about twenty days before the earthquake in Drežnica, which might have predicted the occurrence of earthquake in a longer period. Two days before the earthquake in Drežnica, the terrain compression was also noticed that was rather small since the earthquake occurring after that was of a small magnitude. Up to same such results we obtained by the analysis of permanent GNSS of measurement in Kraljevo (Solarić, N. and Solarić, M. 2012), and too for the earthquake in the Skopje 2016 which we yet analyses. This research indicate that in the Croatia have sense organize the special service in CROPOS which will keep the change of earth's crust in areas with the stronger seismic activity. That refers to areas with the higher number of citizen such as Zagreb, area about nuclear power plant Krško, Dubrovnik, Split and Rijeka. All that can help seismotectonic researchers, that can eventually with other geophysical and new satellite methods (for example TwinSat) (the URL 4, URL 5, URL 6) more surely will announce one's arrival the possibility of earthquake.