People in Croatia have recently experienced two major earthquakes in the midst of COVID-19 pandemic, which are possible sources of increased fear. In order to capture and understand the effects of the simultaneously occurring threatening events, the aims of this study were threefold. First, we aimed to examine the psychometric properties and factor structure of the Croatian version of the Fear of COVID-19 scale (FCV-19S). Second, bearing in mind that there is a lack of instruments for measuring fear of earthquakes, the study aimed to develop and examine the psychometric properties the Fear of Earthquake Scale (FES), as a version of FCV-19S, modified for the earthquake experience. Finally, the study aimed to examine differences in well-being indicators (life satisfaction, positive and negative affect) between four groups of participants who either had/did not have COVID-19 disease or had experienced/did not have experienced earthquake. The study was conducted among 1136 participants adults who took part in the fourth year of the Croatian longitudinal study on well-being. Among them, N = 665 participants experienced earthquake and responded to additional questions regarding that experience. The analyses demonstrated valid psychometric properties and one-factorial structure of FCV-19S and FES scales. The findings showed that people who went through earthquake experience (vs. those without earthquake experience and COVID-19 infection) reported higher negative affect and lower positive affect, indicating that people in Croatia seem to have been more fearful of earthquakes than COVID-19 pandemic. Findings suggest the long-term negative effects of earthquake on fear and well-being in comparison to COVID-19 pandemic.