**4. The 2013 Drežnica earthquake**

On the 30th of July 2013, at 14:58 local time, a minor earthquake occurred in Croatia with an epicenter in Drežnica, 15 kilometres northeast of Senj [5]. The earthquake had a magnitude of 4.6, according to the Richter scale and its hypocenter was at a depth of 20 km. The intensity in the earthquake epicenter was VI-VII on the Mercalli-Cancan-Selberg (MCS) scale.

The earthquake was felt in the Ogulin, Karlovac, and Zagreb areas, as well as in southern and central Slovenia. The county emergency communications centre in Karlovac received only two reports of damage. Given the low intensity of the earthquake, only minor damage was possible in the epicenter area.

We calculated the daily changes in distances and pressure and presented them graphically in **Figure 4**. From the graph, it can be seen where the compression was.

#### **Figure 4.**

*For our analysis, we chose four crops reference stations in Karlovac, Rijeka, Senj, and Slunj, calculated the daily distance changes and presented them graphically. We saw that almost all distances were shortened on the 28th of July 2013 and 2 days later, on the 30th of July 2013, there was an earthquake [6].*

*The Possibility of Earthquake Forecasting, a Few Days before the Earthquake Using GNSS... DOI: http://dx.doi.org/10.5772/intechopen.108848*
