^abIn the Soviet Union, the method of recording the magnitude of earthquakes was different that the more commonly used Richter Scale. The earthquake in Spitak, as defined in the Soviet Encyclopedia, fell between "annihilating" to "catastrophe" which scored as a 10 or an 11 on the Soviet scale. A "10" was described as "great cracks in the earth. Landslides and avalanches" whereas an "11" was described as "wide cracks in the earth. Many landslides and avalanches. Stone houses completely destroyed." For more information on the Soviet grading scale, see Yuri Rost's The Armenian Tragedy. New York: St. Martin's Press, 1990, 193 ISBN 0-312-04611-1.
^abService, Robert (2003). A History of Modern Russia: From Nicholas II to Vladimir Putin. Cambridge, Massachusetts: Harvard University Press. pp. 468–469. ISBN067401801X.