Multifractal Properties of Time Series of Synthetic Earthquakes Obtained from a Spring-Block Model

Area of Science:

• Geophysics
• Complex Systems
• Nonlinear Dynamics

Background:

• Earthquake dynamics are complex and often analyzed using models like the spring-block model.
• Multifractal analysis is a powerful tool for characterizing complex time series, including seismicity.

Purpose of the Study:

• To investigate the multifractal characteristics of synthetic earthquake time series generated by the Olami-Feder-Christensen (OFC) model.
• To analyze the evolution of multifractal spectral parameters before and after large earthquakes in both synthetic and real seismicity data.
• To identify potential precursors to great earthquakes based on changes in multifractal properties.

Main Methods:

• Utilized the spring-block model to generate synthetic earthquake time series with varying conservation levels (β).
• Applied the Chhabra and Jensen method for multifractal analysis of the time series.
• Calculated spectral width, symmetry, and curvature parameters for multifractal spectra.
• Analyzed overlapping windows before and after major earthquakes in synthetic and Southern California seismicity catalogs.

Main Results:

• Increasing the conservation level (β) in the OFC model led to wider multifractal spectra, increased symmetry, and decreased curvature.
• Multifractal spectra exhibited greater width, less left skewness, and sharper peaks before large earthquakes compared to after.
• These multifractal parameter changes were consistently observed in both synthetic data and the Southern California seismicity catalog.

Conclusions:

• The observed changes in multifractal spectra suggest a distinct preparation phase dynamics preceding great earthquakes.
• The dynamics following a mainshock differ from the pre-earthquake preparation phase, as indicated by multifractal parameter evolution.
• Multifractal analysis provides valuable insights into the complex processes underlying earthquake generation and preparation.