Detrended fluctuation analysis of the magnetic and electric field variations that precede rupture

TL;DR

This paper uses detrended fluctuation analysis to study magnetic and electric field variations before rupture, revealing long-range correlations and scale-invariant features that could improve earthquake prediction methods.

Contribution

It applies DFA to pre-rupture magnetic and electric field data, uncovering scale-invariant properties and long-range correlations not previously characterized.

Findings

Magnetic field spikes show long-range correlations with a scaling exponent around 0.9.

Electric field variations exhibit scale invariance with an exponent approximately 1.

DFA reveals different correlation structures at short and long time-lags.

Abstract

Magnetic field variations are detected before rupture in the form of `spikes' of alternating sign. The distinction of these `spikes' from random noise is of major practical importance, since it is easier to conduct magnetic field measurements than electric field ones. Applying detrended fluctuation analysis (DFA), these `spikes' look to be random at short time-lags. On the other hand, long range correlations prevail at time-lags larger than the average time interval between consecutive `spikes' with a scaling exponent $\alpha$ around 0.9. In addition, DFA is applied to recent preseismic electric field variations of long duration (several hours to a couple of days) and reveals a scale invariant feature with an exponent $\alpha \approx 1$ over all scales available (around five orders of magnitude).