Multimodes of Rayleigh wave excited by hurricane Dorian

TL;DR

This study demonstrates that hurricane Dorian's seismic noise can be used to extract high-quality, multimodal Rayleigh wave dispersion curves, enhancing seismic data analysis for Earth's crust and mantle studies.

Contribution

It shows that ambient seismic noise from a hurricane can produce high SNR EGFs with strong directionality, enabling extraction of Rayleigh wave dispersion curves from shorter data segments.

Findings

EGFs exhibit high SNR during hurricane Dorian's passage.

Rayleigh wave multimodal dispersion curves can be extracted from ambient noise.

Seismic noise from hurricanes can extend the data set for Earth's interior studies.

Abstract

Extracting Empirical Green's Functions (EGFs) by cross-correlating ambient seismic noise or coda, considered as an efficient approach of retrieving new response inside the media of two receivers, has been developed well in the past two decades. However, EGFs emerge with high Signal-to-Noise Ratios (SNRs), which needs us to stack a large number of cross-correlations. Here, we retrieve EGFs with high SNRs from ambient seismic noise released by hurricane Dorian moving along the eastern coast of the United States during 3 days in Sept 2019. We systematically analyze the energy sources of seismic noise records with time-frequency analysis and beam-forming. We find that the energy exhibits very strongly when hurricane Dorian progresses along the coast from 4th to 6th Sept. Our results suggest that EGFs exhibit strong directionality and only emerge in the negative part of cross-correlation time functions due to the noise sources of Dorian. We extract clear multimodal dispersion curves of Rayleigh waves from retrieved EGFs. Our results, indeed, reveal that multimodal dispersion curves pf Rayleigh wave could be extracted from ambient seismic noise excited by Dorian for several days or even a single day, which means that we enlarge the seismic data sets for the future work of investigating shear velocity structures of the Earth's crust and upper mantle and understanding our planet more deeply.