The earth's rotation, or rather, its irregularities, affect the activity of volcanoes both in eruptions and in seismic activity: the data collected on Etna indicate this in the research published in the journal Geophysical Research Letters and conducted by Sapienza University of Rome and Paris Observatory.
"There are imperceptible irregularities in the Earth's rotation, but which can only be detected with very sophisticated instruments, such as those that the Paris Observatory has," Gianluca Sottili, professor of Volcanology at Sapienza, coordinator of the study with Sebastien Lambert, explains to ANSA of the Paris Observatory. In fact, the Earth's rotation axis is not always perfectly in line with the North and South Pole. "We wanted to study the effect of these irregularities and the oscillations of the Earth's axis that occur every 6.4 years, discovering - he continues - that their impact is more pronounced in the middle latitudes ". Just at these latitudes is Etna, one of the most studied volcanoes in the world.
"We have thus observed that in recent decades there has been an increase in seismicity and a significant increase in magma in each eruption, corresponding to these oscillations in rotation", continues Sottili. It now remains to be understood why "Etna is sensitive to these orbital factors and whether all volcanoes located in the middle latitudes behave like this or - he notes - only those that have a certain type of volcanic activity, similar to that of Etna ".
Although the results of the study may suggest that earthquakes are more common or volcanoes erupt more lava when the distance between the Earth's geographic axis and that of rotation is at its maximum, according to the researchers it is too long a time scale to be able to make short-term forecasts.