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Seasonal Variations of Seismic Velocity From Air Gun and Ambient Noise Data in the Binchuan, Yunan, China

Session: Waveform Cross-Correlation-Based Methods in Observational Seismology [Poster]

Type: Poster

Date: 4/21/2021

Presentation Time: 03:45 PM Pacific

Description: 

Since 2011, a large-volume air-gun source has been deployed in Binchuan, Yunnan, China for monitoring fault zone at depth. We use repeated air-gun waveforms in the passband of 2-6 Hz to derive seasonal variations of dt/t of P and S waves. We also use ambient noise data in the same frequency range to study seasonal variations of dt/t of scatter waves. Monitoring dt/t of body and scatter waves in the same frequency ranges, we expect to explore the possibility of using air-gun waveforms to reveal seasonal changes of crustal behavior. We deconvolve 28 stations from a reference station near the shooting site to retrieve Green’s functions and compute seismic velocity changes through the moving-window-cross-spectra method. We observe that 1) amplitude of body wave generally increases in the summer; 2) seasonal variations of dt/t of P and S waves correlate with variations of the amplitude of them; and 3) Some dt/t show positive correlation with the amplitude while others show negative relationship, which illustrates the importance of local crustal response. However, to specifically understand how the crust responds to external loadings, we need to better understand the excitation behavior of air-gun sources. We will further compute seasonal variations of dt/t of scatter wave and compare them with changes of body wave to reveal physical meaning behind it.

Presenting Author: Chunyu Liu

Student Presenter: No

Authors