Risk of Another Earthquake Similar to 1977 Bucharest Tremor

According to the volcanologist, one possible explanation for the phenomenon is that the final stage of the rock plate subduction along the Carpathians is taking place. According to the results of geological research, 10–20 million years ago, a high-density rock plate, which once formed the floor of an oceanic basin, fell into the Earth's mantle along the eastern arc of the Carpathians, in a similar way to what is currently happening, for example, along the western edge of South America, along the Andes arc. The formation of the Pannonian Basin, for example, was also a consequence of the rock plate subduction, also known as subduction.

The high-density, oceanic rock plate broke off and continued to sink downwards (the subducting rock plate does not melt in the Earth's mantle), and its material is now visible at a depth of 400–600 km. The breakage did not occur all at once, but gradually in phases from north to south. The last events, the remnants of this gradual detachment, could be under the Carpathian Bend, the university lecturer explained. He added that according to the other theory, this vertical, sinking rigid piece of rock plate was formed when the lower part of the thick continental plate detached and began to sink into the solid but plastic asthenosphere mantle. The piece of rock plate sunk down in the manner of a zipper and is now in a nearly vertical position.

Though the Vrancea earthquakes are not destructive, they are continuous

„Although two different theories explain the current situation, experts agree that the frequent earthquakes in the Vrancea zone are caused by processes occurring within a deep, slowly sinking fragment of the Earth's crust”, the volcanologist pointed out. He pointed out that the earthquakes come from a depth of 60-160 kilometers, meaning that rock body displacements occur here that create earthquake waves.

„These conditions are ongoing, meaning that there are earthquakes almost every week, and from time to time there is a much stronger earthquake than usual, which people also feel. The Vrancea region is not a classic earthquake area, where a big earthquake occurs, followed by countless aftershocks, and then nothing for a long time – here, the earthquakes are continuous,” explained Szabolcs Harangi.

such as Italy, Turkey or Greece, because in the latter areas earthquakes typically occur at a shallower depth (less than 30 km), which means that the impact of the earthquake at the epicenter can be large, even highly destructive. „The Vrancea region is different from those places: rock displacement at such a great depth here means that although a magnitude 5 earthquake may occur, its impact will be smaller at the epicenter, but it can cause surface movement over a much larger area, which can be felt by people,” said the university lecturer.

Earthquakes are impossible to predict, but we must prepare for them

When asked what the current seismic activity indicates and whether we should expect an earthquake of similar magnitude to the 1977 Bucharest quake to shake Transylvania in the near future, Szabolcs Harangi explained that an analysis of earthquake data from the past century shows that the Vrancea region periodically experiences significant tremors, with magnitudes ranging from 7 to 8. As he explained, there is a thirty-fold difference in energy release between earthquake magnitude levels, i.e. the difference between two levels is a thousand-fold.

said the university lecturer. As he put it, if an earthquake of around magnitude 7 occurs, then, as described above, it causes a strongly felt effect, a state of danger, and potentially destruction over a large area. He added that such a large earthquake occurs on average 2-5 times per century, i.e. every 20-50 years. "If we look at the frequency of earthquakes, we see that there are more intense (when earthquakes stronger than magnitude 7 occur) and less intense periods.

The occurrence of such an earthquake in the future must therefore be expected, but it is impossible to say when it will happen,” explained Szabolcs Harangi.

Preparation based on scientific research

The Hungarian volcanologist drew attention to the fact that earthquakes cannot be predicted.

said Szabolcs Harangi.

I must also add that in our current world there are many people who believe that they can predict earthquakes by citing such and such reasons. According to the current state of science, this does not work – it is important that the population listens to the experts. There are now applications that immediately indicate nearby earthquakes – it is worth using these too,” the geologist advised.

Can a volcanic eruption be expected in Transylvania or a tsunami at sea?

Although the precise timing is not known, a more intense period can be expected for the Vrancea region in the future, so it is not a bad idea to prepare for possible earthquakes. Szabolcs Harangi said:

„Although the results of scientific studies suggest that there may still be magma under the volcano (this is the case under many long-dormant volcanoes on Earth), this does not pose an immediate threat; there are currently no signs that the volcano will erupt. If events were to occur in the magma reservoir that could cause a volcanic eruption or magma were to push towards the surface, there would be noticeable signs of this. Although there are no sensitive monitoring instruments on Csomád, such a magmatic process would probably be detected by current instruments”, explained the volcanologist. He added that there was a tsunami in the Black Sea in 1901, but not due to the earthquake in the Vrancea region, but due to the 7.2 magnitude earthquake in Balchik, Bulgaria.