The epicentre of the Croatian earthquakes in March was the northern tip of the Adriatic Sea, in a region known as the “Black Sea”.
The epicenter was at a depth of about 3,000 metres, but the epicentral mass was only about 800 metres deep.
A total of 12,000 people were killed, the Croatian National Disaster Centre reported.
The quake struck at a time of high seismic activity across Croatia.
A report in the daily Hrvatska newspaper said the epicenter of the earthquake was about 600 kilometres south of the city of Trnava.
It said the quake was strongest in the centre of Trna.
The centre of the quake hit near the village of Ljubljana in Trna, the report said.
Croatian officials said the tremors were caused by the eruption of Mount Vesuvius in 79 AD, which killed more than 10 million people in the Balkans.
The eruption was caused by volcanic ash falling on a rocky mountain that was under volcanic pressure, which produced powerful blasts and large volumes of ash.
The explosion caused volcanic flows to erupt, producing huge volumes of steam that flowed to the sea and the atmosphere, and also produced tsunamis that were later recorded as magnitude 8.5 to 8.8, according to the US Geological Survey.