Abstract
By using the newly deduced formula:
M=1.73logΔ+logA-0.83,
where M is the magnitude of an earthquake, and A is the maxium ground amplitude measured in micron at the epicentral distance Δ measured in km., the magnitudes of 1025 earthquakes which took place from 1931 through 1955 in and near Japan have been determined.
The mean annual number N of earthquakes according to the magnitude has been found to be expressed by
logN=-1.08+0.72(8-M),
for ΔM=0.1.
The mean rate of energy release by earthquakes in and near Japan has been estimated to be 1.5×103 ergs/cm2 year or 0.1×10-6 calory/cm2 sec.
As a whole, Japanese area is contributing well over 10% to the total seismicity of the world.
