Phase statistics of seismic coda waves

TL;DR

This study analyzes the statistical behavior of seismic coda wave phases, revealing universal power-law decay patterns and proposing a new method to estimate Earth's heterogeneity based on phase derivative correlations.

Contribution

It provides the first detailed analysis of phase fluctuation statistics in seismic coda waves and links these patterns to Gaussian statistics and heterogeneity estimation.

Findings

Phase derivatives follow universal power-law decay for large values.

Correlation of phase derivatives decays exponentially with mean free path.

Transition between flat and power-law distributions depends on wavelength.

Abstract

We report the analysis of the statistics of the phase fluctuations in the coda of earthquakes recorded during a temporary experiment deployed at Pinyon Flats Observatory, California. The practical measurement of the phase is discussed and the main pitfalls are underlined. For large values, the experimental distributions of the phase first, second and third derivatives obey universal power-law decays whose exponents are remarkably well predicted by circular Gaussian statistics. For small values, these distributions are flat. The details of the transition between the plateau and the power-law behavior are governed by the wavelength. The correlation function of the first phase derivative along the array shows a simple algebro-exponential decay with the mean free path as the only length scale. Although only loose bounds are provided in this study, our work suggests a new method to estimate the degree of heterogeneity of the cr