Energy class – also called energy class K or K-class , and denoted by K (from the Russian класс) – is a measure of the force or magnitude of local and regional earthquakes used in countries of the former Soviet Union, and Cuba and Mongolia.
[1] K is nominally the logarithm of seismic energy (in Joules) radiated by an earthquake, as expressed in the formula K = log ES.
[4] The energy class system was developed by seismologists of the Soviet Tadzhikskaya Complex [Interdisciplinary] Seismological Expedition established in the remote Garm (Tajikistan) region of Central Asia in 1954 after several devastating earthquakes in that area.
[8] V. I. Bune is credited with developing a scale based on an earthquake's seismic energy,[9] although S. L. Solov'ev seems to have made major contributions.
However, proper estimation of ES requires more sophisticated tools than were available at the time, and Bune's method was unworkable.