An attempt to find precursors in the ULF geomagnetic data by means of flicker noise spectroscopy
The flicker noise spectroscopy which is a new phenomenological method for the retrieval of information contained in chaotic time signals, is based on the analysis of recognizable irregularities (pulse, jumps, and discontinuities of derivatives of various order). This method is applied to the ULF (ultra-low-frequency) data observed at Guam in 1992–1994, in order to study the temporal nonlinear behavior of the lithospheric activity prior to the large 1993 Guam earthquake (8 August 1993). We have found that the lithosphere must have exhibited the step-like discontinuous behaviors in the lithosphere 101, 78, 54, 31 and 8 days before the main shock. This kind of nonlinear temporal behavior can be tracked by means of our flicker noise spectroscopy.