Adaptive Approach to Time-Frequency Analysis of AE Signals of Rocks

Area of Science:

• Geophysics
• Seismology
• Acoustics

Background:

• Acoustic emission anomalies in rocks may precede strong earthquakes.
• Effective monitoring requires advanced analysis of geoacoustic signals.

Purpose of the Study:

• To develop and apply a novel adaptive approach for investigating acoustic emission anomalies as earthquake precursors.
• To analyze time-frequency content of geoacoustic signals for seismic event prediction.

Main Methods:

• Utilizing piezoceramic hydrophones and vector receivers as acoustic emission sensors in various water environments and boreholes.
• Employing sparse approximation and a novel Adaptive Matching Pursuit algorithm for time-frequency analysis of geoacoustic signals.
• Adapting the analysis to the specific characteristics of individual geoacoustic pulses.

Main Results:

• Geoacoustic pulse frequency content was observed to change prior to seismic events in the Kamchatka peninsula region.
• The frequency content returned to its initial state post-earthquake.
• These changes suggest a transformation in acoustic emission source scales preceding earthquakes.

Conclusions:

• The developed adaptive approach effectively identifies pre-earthquake acoustic emission anomalies.
• Observed frequency shifts indicate changes in source mechanisms before seismic events.
• Findings support the development of enhanced environmental monitoring and earthquake detection systems.