Statistical Evaluation of Seismic Velocity Models of Permafrost

Abstract

The warming climate in high-latitude permafrost regions is leading to permafrost degradation. Estimating seismic velocity in permafrost can help predict the geomechanical properties of permafrost and provide information for planning and designing resilient civil infrastructure in cold regions. Seismic velocities of permafrost are mainly influenced by three components in permafrost: soil grains, water, and ice. Unfrozen water content reflects the variation of ice content and therefore is a key parameter in predicting seismic velocity. This paper statistically evaluates the performance of seven seismic velocity models in predicting seismic wave velocity of permafrost; these models are the time-average model, Zimmerman and King model, Minshull et al. model, weighted equation model, three-phase model, the Biot‐Gassmann theory modified by Lee (BGTL model), and Dou et al. model. The unfrozen water content used in these models is obtained from a modified Dall’Amico’s model that we propose and this new model is evaluated against six existing unfrozen water content models based on soil temperature. The data used in the evaluation are from published laboratory and in-situ data, including 369 data points for joint P- and S-wave velocities from 9 publications and 980 unfrozen water content data points from 13 publications. This study finds that permafrost of all soil types generally shares the same linear trends between P- and S-wave velocities, regardless of porosity, grain size, and temperature. Fitting all existing data, we derive an empirical linear relationship between P- and S-wave velocities. Among the seismic velocity models evaluated in this study, the Minshull et al. model and BGTL model are the most accurate in predicting seismic velocity of permafrost. The study also provides the applications of seismic velocity models for various permafrost soil types.

Mapping Permafrost Variability and Degradation Using Seismic Surface Waves, Electrical Resistivity, and Temperature Sensing: A Case Study in Arctic Alaska

“…A low-high-low velocity pattern is evident in all models, indicating the active layer and transitional zone (with low velocity), ice-rich permafrost (with high velocity), and partially frozen permafrost with scattered ice (low velocity). Previous studies have shown a strong correlation between permafrost temperature and V s (Ji et al, 2023;Kurfurst, 1976;Nakano et al, 1972). The low-high-low velocity pattern is consistent with the general trend of permafrost temperature variation with depths, as in a previous study (Smith et al, 2022).…”

“…Investigating the long‐term effect of civil infrastructure on permafrost’s stiffness could help improve the engineering design of structures’ foundations on permafrost. Permafrost’s parameters, such as V S 30 and E, are affected by soil types (Coduto, 1999), soil temperature (Ji et al., 2023), and soil’s ice content (Fisher et al., 2020). Changes in these soil properties show possible changes in soil types, thermal conditions, and cryostructure.…”

“…This reduction can affect the soil’s ability to carry loads (as the soil at NOAA 1 is less stiff than the NOAA 3 location), leading to greater settlement or deformation under structural loads. Assuming a V p / V s = 1.6 for the site’s permafrost layer based on (Ji et al., 2023), and γ and g equal to 19.62 kN/m 3 and 9.81 m/s 2 , respectively, Equations 1–3 result in an elastic modulus of 261.07 MPa at the NOAA 1 location and 301.31 MPa at the NOAA 3 location. This indicates a 13.35% reduction in elastic modulus accompanied by an equivalent increase in settlement values, as delineated by Equation 4.…”

“…Permafrost structure is often complex due to fine‐scale spatial heterogeneity of properties such as temperature and ice content. Temperature, water saturation, and ice content influence seismic wave velocities, including shear wave velocity ( V s ) and compressional wave velocity ( V P ) (Coduto, 1999; Hjort et al., 2022; Ji et al., 2023; Liew et al., 2022; Rocha dos Santos et al., 2022). Salinity is a key factor in coastal permafrost environments such as Utqiagvik, Alaska.…”

“…Seismic imaging is a commonly used technique for characterizing the subsurface in permafrost regions (e.g., Justice & Zuba, 1986; Miller et al., 2000; Ramachandran et al., 2011), because seismic wave velocities, including shear wave velocity and compressional wave velocity, are sensitive to temperature, water saturation, and ice content (Coduto, 1999; Hjort et al., 2022; Ji et al., 2023; Liew et al., 2022). One of the main advantages of seismic imaging in permafrost regions is its ability to provide detailed information about the distribution and continuity of permafrost and the nature of the underlying soils, even 3D profiles with high resolution (e.g., Ramachandran et al., 2011; Schwamborn et al., 2002).…”