Diagnostics of Metainstability in Seismically Active Faults

This study presents a synergetic approach for diagnosing the pre-seismic state of seismoactive faults. Using experimental data from a loaded system of two blocks, it was discovered that the displacement of blocks is preceded by two dynamic states: metainstability I, characterized by autowave oscillation regimes, and metainstability II, which includes initial and late stages. During the initial stage, quasi-creep displacement allows stress release in the inter-block contact zone. In the subsequent accelerated synergism stage, displacement velocity increases, self-organization occurs, and the dynamic slip impulse leads to an avalanche-type consolidation. Spectral analysis of strain monitoring data, particularly from the Kultuk earthquake (M=6.3) in Lake Baikal, supports these findings. Identifying structural features in spectrograms could enable differentiation of metainstability stages in seismically active faults.