On satellite images of Lake Baikal, on the spring ice, you can sometimes see dark rings 5-7 km in diameter. For the first time such a ring was seen in a satellite image taken in April 1999. The ring was located opposite Cape Krestovsky (see illustration)
The next time a similar ice phenomenon was recorded at the same place in April 2003, and then in April 2005. In 2004, 2006 and 2007 there were no ring formations on the ice of Lake Baikal. In 2008, rings appeared in two places: again in the area of Cape Krestovsky (with some displacement to the south-west from the location of the ring in 1999, 2003 and 2005) and, for the first time, in the area of the village of Turka. In 2009, two rings were again recorded in new places: to the west of Cape Nizhneye Izgolovye of the Svyatoi Nos Peninsula and in the southern tip of Lake Baikal, the information resource Baikal-Center reports.
The causes and mechanism of the formation of annular ice phenomena have not been studied in detail at present.
Presumably, the formation of circles is associated with emissions of natural combustible gas (methane) from the many kilometers of sedimentary strata of the bottom of Lake Baikal. It is known that in some parts of the water area, natural gas escapes from the bottom constantly. In summer, in such places, bubbles rise from the depths to the surface, and in winter, "proparins" with a diameter of half a meter to hundreds of meters are formed, where ice is very thin or even absent. But giant dark rings on the ice of Lake Baikal are formed when natural gas is released of an abnormally large volume. Probably, such emissions are associated with seismic activity and tectonic movements in the Baikal rift system.
According to scientists, the formation of dark rings on the ice surface supposedly occurs as follows. Rising from the bottom of Lake Baikal, natural gas provokes an ascending water flow, which, in the process of ascent, is twisted by the Coriolis forces caused by the Earth's rotation (similarly to how cyclones and anticyclones are formed in the atmosphere). As a result, a circular relatively warm current forms in the near-surface layer of water under the ice, which gradually destroys the ice cover from below. Melted ice is saturated with water, and a dark ring appears on the surface of the ice. Subsequently, within the formed circle, the ice melts faster than in the nearby parts of the water area.
Most likely, such abnormal emissions of natural gas have always occurred on Lake Baikal, and such ice rings are not a new phenomenon for Lake Baikal. But, due to its enormous size, it is almost impossible to see the ring from the ice and even from the mountain. Therefore, they began to be noticed only recently, when the daily space monitoring of the Baikal natural territory began to be carried out on the orders of the Ministry of Natural Resources of Russia.
According to the data of the Baikal Regional Computer Center, in 2009, in the area of Cape Nizhneye Izgolovye of the Svyatoi Nos Peninsula, the annular ice formation is the most anomalous over the entire ten-year observation period. This is probably due to the intensification of geological processes in this area. On April 24, 2009, in the ice cover, the thickness of which in this area is usually about 1 meter in March-April, a circular polynya with an area of 35 square kilometers was formed (according to the SPOT satellite imagery, the spatial resolution is 10 meters). For comparison, the area of the largest "stationary" polynya from steaming, which was recorded at the same time in the Barguzinsky and Chivyrkuisky bays, is no more than 0.1 square kilometers.
The study of annular ice phenomena on Lake Baikal is of considerable scientific interest. It is necessary to study in detail the factors and mechanism of ring formation, as well as the relationship of the ongoing processes with seismic and tectonic activity.
Experts note that the scale and intensity of manifestation of the ongoing processes characterize their high danger for vehicles moving on ice roads, for fishermen and residents of nearby villages. It is obvious that abnormally large emissions of combustible gas can occur in these areas in the summer-autumn period and create a danger for ships and their crews.