Monitoring Nonlinear Elasticity Near Dalk Glacier in East Antarctica

Understanding the nonlinear elastic behavior of rocks has primarily been based on laboratory observations or numerical simulations. However, due to the inherent complexities and uncontrollable nature of real-world systems, field measurements of nonlinear elasticity remain a significant challenge. In-situ “Pump-Probe” type experiments, analogous to those conducted in laboratories, provide a valuable approach for characterizing the nonlinear mechanical properties of Earth materials. Environmental factors, such as tidal forces, hydrological loading, and thermal elasticity, serve as potential “pump” sources for these experiments. Seismic wave relative velocity changes (dv/v) are crucial proxies for investigating nonlinear elastic variations within the Earth's crust.

 During the 36th Chinese Antarctic Expedition, we conducted a “Pump-Probe” type experiment near Dalk Glacier in East Antarctica. Over the course of one month, we collected ambient seismic noise data from the region. By reconstructing the noise cross-correlation functions (NCFs) from this seismic data, we applied coda wave interferometry to calculate dv/v.

This study further explores the hysteresis characteristics of dv/v in relation to strain, further analyzing the temporal delay effects of dv/v in response to various environmental factors, including tidal forces, temperature, humidity. Through time-domain analysis, we quantified the lag of the dv/v time series relative to the environmental parameters. In the frequency domain, we examined the diurnal and semi-diurnal variations in dv/v and their correlation with environmental factors, shedding light on the underlying mechanisms driving the observed fluctuations.

Additionally, we applied degree-day model and energy balance model to assess the melting dynamics of the ice sheet, allowing us to examine the response of dv/v to ice sheet melting. These findings contribute to a deeper understanding of the complex interactions between environmental factors and nonlinear elasticity, with potential implications for monitoring subsurface disturbances in polar regions.