On Tuesday 30 October, slightly after 6.10 pm local time (slightly after 10.10 am, GMT), a magnitude 4.5 Earthquake occurred 17.9 km beneath Lake Baikal in Siberia, according to the United States Geological Survey. This is large enough that it was probably felt in the area, but probably not to cause any problems, and no damage or injuries have been reported.
Composite satellite image showing the position of the 30 October Earthquake and of Lake Baikal. Google Maps.
Lake Baikal is the oldest and deepest freshwater lake in the world, over 1637 m deep and 400 km long and having formed 20-25 million years ago it is a biodiversity hotspot, hosting amongst other things the world's only freshwater Seal. The depth and longevity of this lake is due to its unique geology (most lakes are just large depressions filled with water); Lake Baikal is part of a forming rift system, with the potential to eventually split the great continent of Eurasia in two (not all rift systems live up to this potential, many stall, and either stop growing or close again). The rift extends southwest from the Lake, forming the Tunka Basin of Siberia. The rift is growing at a rate of about 4.5 mm per year around the lake, and 6.3 mm per year in the Tunka Basin. This has lead to some large Earthquakes on the system, including a Magnitude 9 quake in August 1959, which displaced the bottom of the lake by up to 20 meters.
If the Baikal Rift system continues to open it will eventually grow into a continent-spanning rift like the Great Rift Valley of Africa, then a narrow ocean like the Red Sea, and eventually a fully mature ocean like the Atlantic.
Simple diagrammatic representation of rifting on the Baikal Basin. Krylov et al. (1993)/Technische Universität Bergakademie Freiberg.
See also Earthquake in Tajikstan, Earthquake in Tuva Republic, southwest Siberia, Major Earthquake in southwestern Siberia. 27 December 2011, Earthquake on the Kyrgyzstan/Uzbekistan Border, 20 July 2011; at least 14 people dead and Earthquakes on Sciency Thoughts YouTube.
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