The earth’s crust under the lake cavity is being formed. Powerful seismic activity is characteristic of the whole territory of the Baikal mountain region. The seismic activity creates specific difficulties for all kinds of construction and needs making special maps of seismic activity.
The Russian school of seismology at Lake Baikal was born in the late 19th century by the efforts of the scientists A.P. Orlov and P.A. Kelberg. They were the first to study the earth’s crust vibrations at Lake Baikal (1869), made notes on the consequences of the force 10 earthquake in the Tsagan valley on January 12-13, 1861. At that time the steppe was furrowed with deep clefts from which water gushed out, and the land started sinking slowly. 203 sq. km of the Baikal coast including 5 Buryat uluses (villages) sank into the water having formed the Proval (Gap) gulf. The first shock on January 12 was force 9, on January 13 the shock was force 10. There were fading shocks for 16 months more. The people who had saved themselves moved to other, raised places. The Posolsky sor (cove) (on the southern side of the Selenga river delta) is also supposed to be formed by a great earthquake.
On April 4-5, 1950 there was a force 9 earthquake near the village of Mondy, it repeated on September 8. As a result many rock-slides and clefts in the earth’s crust were formed.
In 1951 a force 7 earthquake was recorded on Olkhon island.
In 1959 the bottom of Lake Baikal sank 15-20 m after the 9.5 force earthquake.
In June 1981 a force 9 earthquake was recorded near Svyatoi Nos cape.
There is no common opinion among scientists on the frequency of earthquakes on the Baikal coast. In V.V. Lamakin’s opinion great Baikal earthquakes take place periodically, every 7-10 years. According to G.G. Galazi, there are 2-3 catastrophic force 8-10 earthquakes a year, and there are less strong earthquakes “in dozens and thousands throughout a year”. The seismotectonic and geological research give evidence on the fact that great earthquakes in the Baikal land are connected with horizontal dislocations of the earth’s crust.