Seismic refraction surveys for predicting the intensity and depth of weathering and fracturing in granitic masses

Abstract

Seismic refraction surveys were employed for shallow investigations (down to 20-30 m depth) and conducted across the top of vertical exposures where the underlying geology could be directly inspected. The suitability of shallow seismic refraction surveys for identifying the intensity and depth of rock weathering and fracturing at the respective locations could thus be correctly assessed. Research completed on granites of Jurassic and Cretaceous age from Korea had previously indicated that these granitic materials could be divided with reasonable accuracy into five weathering groups using visual and simple mechanical techniques. Weathering boundaries determined by seismic refraction methods were found to agree within a 2 m variance with visible differences in weathering in the vertical exposure beneath each test site. The intensity of fracturing could also be predicted by seismic refraction surveys with relatively good accuracy. It was concluded that the field seismic survey method in shallow Korean granitic masses could be considered a very useful and cost-effective technique for assessing the intensity and depth of weathering and fracturing.

Mapping variations in bedrock weathering with slope aspect under a sedimentary ridge-valley system using near-surface geophysics and drilling

“…Vp is a measurement of bulk material strength that depends on lithology, porosity, moisture content, and chemical weathering. Several studies have shown good agreement between Vp and rock strength or fracture density (e.g., Clarke & Burbank, 2011;Flinchum, Holbrook, Rempe, et al, 2018;Holbrook et al, 2019;Lee and de Freitas, 1990;West et al, 2019), as well as chemical mass loss (Gu et al, 2020).…”

Geophysical Measurements to Determine the Hydrologic Partitioning of Snowmelt on a Snow‐Dominated Subalpine Hillslope

“…Seismic refraction methods can be used to characterize the weathering front structure in alpine watersheds with crystalline bedrock (Befus et al, ; Lee & Frietas, ). Seismic data were collected on 18 July 2016 along a line approximately parallel and directly adjacent to the ERT line “L.” All geophones were spaced 1 m apart and shots were positioned every 5 m. Data were collected with a Geometrics 24 channel Geodes and 4.5 Hz geophones.…”

Mapping Variations in Bedrock Weathering With Slope Aspect Under a Sedimentary Ridge‐Valley System Using Near‐Surface Geophysics and Drilling

“…Vp is a measurement of bulk material strength that depends on lithology, porosity, moisture content, and chemical weathering. Several studies have shown good agreement between Vp and rock strength or fracture density (e.g., Clarke & Burbank, 2011; Flinchum, Holbrook, Rempe, et al., 2018; Holbrook et al., 2019; Lee and de Freitas, 1990; West et al., 2019), as well as chemical mass loss (Gu et al., 2020).…”