The seismic and volcanic activity of Mount Etna correlates with the periodic movement of the poles of the Earth, which leads to small deformations of the earth’s surface. This conclusion was made by scientists from France and Italy, analyzing data on the activity of Etna in recent decades. This article was published in the journal Geophysical Research Letters .
The earth is periodically deformed on a small time scale due to several phenomena. The biggest influence is exerted by tidal forces arising from the influence of the Moon and the Sun on the Earth. This interaction results in a surface deformation of approximately 30 centimeters per day. In addition, periodic changes in the length of the day also lead to surface deformation by about a millimeter. Finally, another significant deformation factor is the movement of the poles of the Earth . The fact is that the Earth’s axis of rotation periodically shifts, essentially spinning in a spiral. This movement has a period of about a year, as well as a heartbeat with a period of 6.4 years, at which the amplitude of the movement reaches a maximum.
The deformation of the Earth’s surface due to the movement of its poles depends on latitude and reaches a maximum of about a centimeter at 45 parallels. This may seem insignificant in order to influence large-scale processes, but studies show that the deformation of the Earth due to the movement of the poles affects seismic processes.
Sebastien Lambert from the University of Paris and Gianluca Sottili from the University of Sapienza of Rome decided to check whether the Earth’s pole movements affect volcanic processes. As the object of study, they chose the volcano Etna, for which there is a large amount of data. In addition, it is convenient in that it is located on the 37th parallel, on which the deformation from the movement of the poles is close to maximum.
As the data, scientists took measurements of the position of the axis of rotation of the Earth, data on earthquakes at a distance of 43 kilometers from the peak of Etna, as well as data on volcanic eruptions. In total, data cover 227 months (almost 19 years). Comparison of the seismic energy graphs and the radius of the pole motion showed that both quantities change in a similar way and their peak values fall on 2002 and 2009. In 2015, the peak is not so pronounced, because the amplitude of the pole movement in recent years has been falling. In addition, the data showed that the poles are most affected by the movement of the poles of the region no further than 30 and no deeper than 20 kilometers from the crater of the volcano. The data also showed a correlation between pole movement and eruptions.
The Earth’s magnetic poles are also subject to movement, moreover, this movement is more substantial, and not throughout the course of history they even changed places .