Seismic Parameters and Their Physical Meaning

Abstract

This chapter describes the physical meaning of the seismic source parameters. Earthquake source parameters were derived over a long time period in order to get first of all a measure and then a better understanding of them. With time, seismology was introduced to the mines and it was found that there was a lot of similarity between the large earthquakes and the smaller size seismic events recorded in mines. Spectral analysis has become a standard technique used to estimate the source parameters of seismic events recorded by mine digital seismic networks. Simple source models of circular dislocations are used for the interpretation of seismic spectra and for the purpose of deriving source parameters. Seismic moment, corner frequency and seismic energy are inverted from the spectra that are corrected for the instrumental, distance and attenuation effects of each waveform and then averaged. Seismic source parameters are not measured, they are estimated. There is a difference between a measurement and estimation. Understanding these differences results in understanding the limitations of the source parameters. The reliability of seismic data is low. It is my experience that most or a lot of its users do not realise that the seismic source parameters they are using for interpretation purposes are only estimates. Their values are not derived from a process of a measurement. The reality is that the seismic source parameters are just an educated guess.