Earthquakes are one of the most serious natural disasters. There are about 5 million earthquakes in the world every year, including about 50000 felt earthquakes. Large earthquakes of magnitude 7 and above that can cause catastrophic damage have occurred more than 1200 times in this century. So far, however, no major earthquake has been recorded on the Antarctic continent. Everyone lives on the earth, why is there no earthquake in the South Pole?
1. The thick ice layer is the main reason why there are no earthquakes in the Antarctic continent
According to statistics, the ice and snow coverage of the Antarctic continent and Greenland has reached more than 90% and 80% respectively, and the ice cover is thick. Due to the pressure of the ice, its bottom is almost in a "molten" state. At the same time, due to the large area and heavy weight of the ice layer, it produces strong compression in the vertical direction, and the huge pressure formed by the ice layer disperses and weakens the deformation of the crust, which is in balance with the compressive force of the stratum structure, so it will not tilt and bend. Therefore, it disperses and weakens the deformation of the crust, so it is unlikely to have an earthquake in the South Pole. Greenland, the world's largest island in the Arctic, also has fewer earthquakes for this reason.
2. The famous theory of continental plate drift
It is considered that the compression between plates causes earthquakes, and the earth rotates on the North-South polar axis. Most of the main seismic zones on the earth are located at the land and sea edge and about 30 ° north-south latitude, and most of the mountains and rivers in the world are gathered here. However, the position of the earth's two poles lies precisely on the poles. The south pole is a relatively complete plate structure. There is no plate junction and no plate compression. It will not be affected by the drift force from east to west and north to south. Therefore, there will be no earthquake if other plates do not squeeze it. Therefore, it is difficult for the two polar regions to have self-sustaining earthquakes. Even if there is vibration, it is also affected by the surrounding earthquakes.
In fact, earthquakes can occur anywhere, but the frequency and magnitude of earthquakes are different. Earthquakes that occur in some seismic zones have larger magnitudes and higher frequencies, such as the Pacific rim and the Qinghai Tibet Plateau. In some places, such as Siberia, earthquakes are mostly small, and the frequency is much lower.
Specific to the north and south polar regions, earthquakes actually occur. If the south pole is defined as the part within 60 ° s latitude, there will be some relatively large earthquakes. However, it is very stable within 70 ° south latitude, and there will be some small earthquakes with low frequency. Most parts of Antarctica are stable plots. The period of major earthquakes can reach thousands or even thousands of years, and they are isolated overseas. Before the invention of seismograph, even major earthquakes with a magnitude of more than 8 in Antarctica will not be recorded. However, the seismograph has been effectively used to record earthquakes for only a hundred years, and the major earthquakes there may not be recorded, so it gives the impression that earthquakes are not easy to occur in Antarctica.