Recently, a number of research findings have come to light about the age of plate tectonics, and energies are needed to operate it. The aim of present study is to investigate whether the energy of plate tectonics process was different during the Phanerozoic (Pz) and in earlier eons, and if there is such a discrepancy, whether it can be justified by changes in the processes that able to move the plates. The study will track temporal changes in important components of plate tectonics such as length of mid‐ocean ridges, subduction zones and relative oceanic crust coverage during Phanerozoic. Next, it will be examined how the knowledge gained in this way can be reconciled with the results of studies of previous eons. It was found that the temporal variation in kinetic energy of axial rotation due to changes in length of day (LOD) can be assumed as a determining energy which acts on the tectonic plates as in the Phanerozoic as earlier in Archean (Arch) and Proterozoic (Ptz).

<p>The secular change in the flattening of Earth and its effect on global tectonics is a subject still to be investigated.</p><p>Tidal friction causes a constant despinning of the rotation of Earth. It happens at a rate of <em>Δω = – (5.4 ± 0.5) ∙ 10<sup>-22</sup>s<sup>-2</sup></em>, resulting in a change of the length of day with <em>∆LOD = (2.3 ± 0.1) ms/century</em> (Stacey, 1992). The slowly decreasing rotational speed creates a change in the flattening of the Earth, that produces a latitude dependent stress field. The meridional stress component is always positive (i.e. tensional), while the azimuthal stress is negative (i.e. compressional) from the equator, up to the critical latitudes (~ ±48.2°), and positive poleward. This means two major tectonic provinces: in the equatorial region a strike-slip province and towards the poles, a normal fault province (Denis & Varga, 1990).</p><p>From the 1960s reliable seismological catalogues are available. ISC GEM Catalogue contains re-computed moment magnitude (Mw) values, what is essential for calculating the released seismic energy, since at higher magnitudes, it doesn’t go into saturation. One can obtain the energy released by an event with the formula <em>logE = 5.2 + 1.44Mw</em> (Båth, 1966). Based on this catalogue, a 52-year period with moment magnitudes higher than 5.8, all in all 8799 events were used.</p><p>Our study shows that the effect of the despun Earth is reflected in the latitudinal distribution of earthquake energy, which is symmetric with respect to the equator and there are clear maxima at mid-latitudes. The distribution of seismic energy released by either normal fault or strike-slip earthquakes also follow a pattern previously described. Especially on the northern hemisphere normal fault events occur dominantly towards the poles while strike-slip earthquakes tend to happen at lower latitudes. We can conclude that tidal friction actually creates the proposed stress field on Earth, and is visible if we observe how global seismicity behaves with respect to latitude.</p><p> </p><p>Båth, M. (1966). Earthquake energy and magnitude. Physics and Chemistry of the Earth, 7, 115-165.</p><p>Denis, C., Varga, P. (1990). Tectonic consequences of the Earth’s variable rotation, In: Brosche P, Sündermann J (eds.) Earth rotation from eons to days. Springer, pp. 146-162.</p><p>Stacey, F. D. (1992). Physics of the Earth, Brookfield Press, Australia, ISBN 0-646-09091-7.</p>

This study aims to determine the epicenters and magnitudes of pre-instrumental historical earthquakes in the Pannonian basin based on contemporary sources and the literature that recorded the effects, damage, and accompanying events. A local intensity value for a given place was estimated only if it could be determined based on contemporary data. Using intensity data from different locations, the position of the hypocenter and magnitude of the historic earthquakes were calculated using an empirical equation. The epicenter positions were compared with the spatial distribution of liquefaction phenomena, foreshocks, and aftershocks, for which data were available. Finally, the set of historical Mw≥5.5 events is supplemented with locations of instrumentally measured earthquakes of similar sizes, and the relationship between the location of the resulting seismic events and the main tectonic structures of the Pannonian basin is investigated. Our investigation suggests that the location of the earthquake epicenters is not linked to known major tectonic structures and that the earthquake activity in the Pannonian basin may be higher than previously thought.