[J01-P] Poster

[J01-P-03] Temperature dependent seismic-frequency attenuation in ice and permafrost

^○Seth Saltiel^{1, 2}, Brian Bonner², Shan Dou², Jonathan Ajo-Franklin² (1.UC Berkeley, Berkeley, CA, USA, 2.Lawrence Berkeley National Lab, Berkeley, CA, USA)

There is an increasing interest in cryoseismic waves and their ability to monitor seismogenic processes and environmental conditions in the cryosphere [Podolskiy and Walter 2016]. However, laboratory work to understand and interpret this information is lacking, especially near the melting point and at seismic frequencies. For example, seismic attenuation in ice and permafrost is very sensitive to temperature, especially close to the melting point, providing the opportunity to obtain temperature profiles from seismic data, given controlled experimental attenuation databases. Peters et al. [2012] estimated englacial temperature from a seismic survey based on resonance measurements, >100 Hz, on ice cores [Kuroiwa 1964], showing good agreement with other measured and modeled temperature profiles in the area. This technique could be improved with seismic-frequency laboratory measurements. In saline permafrost, 1 MHz P-wave attenuation was measured to increase dramatically near the eutectic temperature, suggesting a wave-induced phase change attenuation mechanism [Dou et al., 2016]. Broadband measurements and comparison to crystallization kinetics could confirm this hypothesis. We have adapted a seismic-frequency (0.1 - 100 Hz) sub-resonance apparatus [Saltiel et al., 2017] to measure shear modulus and attenuation of frozen materials under controlled temperature conditions. These measurements can be directly applied to ongoing efforts to use active and passive seismic surveys to measure englacial temperature profiles and monitor permafrost thaw. We are also pursuing laboratory experiments to contribute to our understanding and interpretation of seismic data of glacier bed sliding frictional behavior, and ice tensile/shear fracturing to constrain calving and crevassing rates. New experimental facilities make the systematic exploration of the seismic properties of frozen materials possible, which will increase the accuracy and utility of cryoseismology datasets.