by Gennady UFIMTSEV, Dr. Sc. (Geol. & Mineral.), Institute of the Earth's Crust, RAS Siberian Branch
One of Lake Baikal's bays, Proval, seems to have nothing special about it: the same low shores, waterlogged in places, against a backdrop of sand dunes and burnished hills... And yet this bay is a standout by virtue of its very birth: on New Year's eve (December 31, 1861 -or January 12,1862, by the Gregorian Calendar) part of the Selenga river delta and adjacent plains suddenly sank in on area 260 sq. km.
The very name, proval, means "sink", or "pit". Its birth was preceded by the most violent earthquake on Baikal's record: its magnitude (M) is estimated to have been 7.5. And about a hundred years later, on August 29, 1959, another disastrous quake hit the Baikal area (M=6.8 and force, 9 points on the macroseismic scale). And farther to the northeast there lies Cape Oblom ("break" in Russian). Both names- proval and oblom-are illustrative enough.
The bay is close to a triangle in shape, with the mainland shore in the east, the edge of the Selenga delta in the southwest, and the subwater bank Sakhalin separating the inlet from the open water area. This very bank (shoal) saved people just after the Tsagan Steppe (plain) suddenly sank below the lake's level. The ice jams and hummocks at low depths prevented the Baikal waters (including the only tidal wave, "tsunami") from rushing into the newly formed sink, and the Buryat population managed to escape, even though thousands head of cattle perished. Russian-populated villages suffered less, situated as they were on a terrace whose ledge turned into the shore of the new bay, from 2 to 6 meters deep now.
Eyewitnesses left their accounts of what happened more than 140 years ago. In 1865 the Gorny (Mining) Journal published perhaps the most substantive eyewitness account by Fitinhof. Unfortunately this article cites no instrumental evidence (since no seismic arrays were in existence then). But be it as it may, the Pro ... Read more