Single-Station Coda Wave Interferometry: A Feasibility Study Using Machine Learning.

Erik H Saenger,Pejman Tahmasebi,Sadegh Karimpouli,Claudia Finger

doi:10.3390/ma14133451

Abstract

Coda wave interferometry usually is applied with pairs of stations analyzing the signal transmitted from one station to another. A feasibility study was performed to evaluate if one single station could be used. In this case, the reflected coda wave signal from a zone to be identified was analyzed. Finite-difference simulations of wave propagation were used to study whether ultrasonic measurements could be used to detect velocity changes in such a zone up to a depth of 1.6 m in a highly scattering medium. For this aim, 1D convolutional neural networks were used for prediction. The crack density, the crack length, and the intrinsic attenuation were varied in the considered background material. The influence of noise and the sensor width was elaborated as well. It was shown that, in general, the suggested single-station approach is a possible way to identify damage zones, and the method was robust against the studied variations. The suggested workflow also took advantage of machine-learning techniques, and can be transferred to the detection of defects in concrete structures.

Highlights

In Earth sciences, it is known that coda waves are sensitive to changes in the subsurface because the strong scattering that generates these waves causes them to repeatedly sample a limited region of space [1,2]
Coda wave interferometry (CWI) is a technique that exploits tiny waveform changes in the coda to detect those variations of seismic properties in evolving media ([3] and references therein)
CWI was introduced to civil engineering experiments [5]

Summary

Introduction

In Earth sciences, it is known that coda waves are sensitive to changes in the subsurface because the strong scattering that generates these waves causes them to repeatedly sample a limited region of space [1,2]. Coda wave interferometry (CWI) is a technique that exploits tiny waveform changes in the coda to detect those variations of seismic properties in evolving media ([3] and references therein). A standard application setup for load tests of a concrete beam was described in a recent paper [6]: The material perturbations were detected around and in between a pair of a source and a receiver. They pointed out that the most common way to analyze coda waves is the correlation coefficient

Results

Discussion

Conclusion