-

Magnitude has played a particular role in the realistic description of global seismicity. Most studies in earthquake seismology use magnitude
data as a guide to the strength of an earthquake. So biases in magnitude estimates, caused by any effect, directly affect the result of any study in
which magnitude data is used. In this study, efficiency of using different formulae and depth-distance calibration terms are examined.
Applications of the MsR-P formula and new depth-distance terms to the ISC dataset, show that the estimated Ms and mb values are
independent of distance, and provide unbiased estimates of Ms and mb in comparison with commonly-used Prague formula and Gutenberg-Richter
terms. Comparison of standard deviation of Ms values for single events using the MsR-P and _rague formulae show that the _-P standard deviations are consistently smaller than those of Prague formula. Also
standard deviations of estimated mb values using the new depth-distance terms are smaller than standard deviations of estimated values using Gutenberg-Richter terms. Estimated Ms and mb values using _-P
formula and the new depth-distance terms reduce overlap in Ms:mb criterion for underground explosions and earthquakes. The study reported here confirms the need to modify the formula for Ms calculation and depth-distance correction terms for mb calculation, which are used by
global agencies such as ISC and NEIC