Abstract
When a chain-reaction-type fracture formation is postulated at a seismic source (OTSUKA, 1972), the seismic energy account turns out to be influenced by the activity of earthquakes with moderate magnitudes in contrast to the generally accepted idea that it is primarily controlled by the activity of major earthquakes.
While this current idea is needed to provide an independent explanation for the cut-off phenomenon of seismic energy for large earthquakes, the chain-reaction model demonstrates that it originates from the very nature of seismic phenomenon itself.
