is there any theory on it?
Yes. Dislocation theory is used to determine part of an earthquake's focal mechanism and to show that a dislocation was indeed equivalent to a double couple
Moment magnitude scale
 In a series of papers starting in 1956 she and other colleagues used dislocation theory to determine part of an earthquake's focal mechanism, and to show that a dislocation – a rupture accompanied by slipping — was indeed equivalent to a double couple,

what was the scale of 2005 qeshm earthquake? 5.8 where did it occur? Qeshm Island off Southern Iran any casualties because of it? 13 People were killed describe in few words the damage it caused? In Zirang, a village on Qeshm, 80 percent of the buildings were demolished. Seven villages experienced extensive damage, and 13 villages were destroyed what is the terminology for the scale which measures the intensity of an earthquake? Moment magnitude scale is there any short definition for it? It is a measure of an earthquake's magnitude based on its seismic moment (a measure of the work done by the earthquake)
wiki:13107007
Moment magnitude scale [SEP] Dislocation theory
H. Love in 1927. More generally applied to problems of stress in materials, an extension by F. Nabarro in 1951 was recognized by the Russian geophysicist A. V. Vvedenskaya as applicable to earthquake faulting. In a series of papers starting in 1956 she and other colleagues used dislocation theory to determine part of an earthquake's focal mechanism, and to show that a dislocation – a rupture accompanied by slipping — was indeed equivalent to a double couple, In a pair of papers in 1958, J. A. Steketee worked out how to relate dislocation theory to geophysical features. Numerous other researchers worked out other details, culminating in a general solution in 1964 by Burridge and Knopoff, which established the relationship between double couples and the theory of elastic rebound, and provided the basis for relating an earthquake's physical features to seismic moment.