Observations of multiple seismic events

摘要: Two or more dispersed wave trains each with constant amplitude will interfere giving a resultant wave train which is modulated, if the individual waves have their principal energies in common frequency band and arrive time separations small compared to total length. The dispersive characteristics of need not be the same. If component are comparable magnitude, modulation due interference becomes significant "beat" phenomenon occurs. Multiple dispersed seismic surface may occur because temporal and/or spatial distribution at the source multipath propagation. Each these causal mechanisms influences the amplitude phase spectra resultant train; derived properties such as phase velocities ratios also influenced. In case propagation, wavelength dependent delays occur. cases twin earthquakes analyzed, and features interference demonstrated. one case, estimates obtained for ratio delay second shock respect first. The interpretation seismograms influenced by multiple events discussed.