Earthquakes in the Pacific region occur at different seasons of the year and with different frequency. Scientists from the Shirshov Institute of Oceanology RAS and the Institute of Marine Geology and Geophysics FEB RAS in Yuzhno-Sakhalinsk have proved that these differences are not by chance and that the position of the Earth in its orbit influences their frequency.


The researchers reviewed the within-year distribution of earthquakes for several subregions of the Pacific Ocean: on the Aleutian Islands, Kuril Islands and Kamchatka, New Zealand and in several points in the south of Oceania and South America. They divided all earthquakes in terms of the magnitude of their nidus and depth. The analysis showed that deep earthquakes occur evenly over the course of the year, while shallow ones occur more often in December.

They believe that the December peaks of shallow earthquakes are linked in part with tidal effects, while their periodicity is linked with the movement of the Earth in orbit. The perihelion, the minimal distance of the Earth from the Sun, comes in early January. At this time the tidal forces, brought about by the Sun, reach a maximum, just as the Sun’s linear velocity in orbit. The scientists remind us that the catastrophic Indonesian earthquake of 2004 occurred on 26 December, when the Earth was nearing perihelion, in a New Moon, when the total effect of tidal forces of the Sun and Moon had reached a maximum level. The Iranian earthquake of 2003 also occurred on 26 December.