Subsurface critical zone patterns and controls inferred from large-scale near-surface seismic velocity data
Abstract
The time-averaged shear-wave velocity of the first 30 meters (VS30) has been used to infer subsurface rock structure, properties, and ground-motion amplification in engineering geology. Dense VS30 and primary-wave (Vp) measurements are available for tectonically active regions such as Japan or southern California. Subsurface processes such as bedrock weathering can result in mechanically weakened rocks resulting in a reduced seismic velocity that would be reflected in Vp profiles and VS30. Previous studies showed that VS30 are empirically related to topographic attributes (e.g., slope, local relief, curvature) and their relations vary depending on the length scales of topographic attributes and different geologic groups. In this study, we examine whether we can infer subsurface critical zone patterns and controls using dense VS30 and Vp measurements available in Japan. We consider 1,613 strong-motion seismic stations and choose 649 stations that have paired borehole Vp profiles and VS30 determined from the strong-motion seismograph networks, K-NET and KiK-net, in Japan to determine subsurface critical zone structure and depth. Then, we examine the correlation between VS30, Vp profiles, and various geomorphometrics to consider the length scales of characteristic landforms, their positions, geologic groups. We convolve the digital elevation models by using either a smoothing window or a local relief window with various length scales of radii ranging from 100 to 2,500 meters. Our analyses have the potential to improve understanding about relationships between large-scale near-surface seismic velocity distribution, subsurface critical zone structures, and topographic attributes.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMNS0140002K
- Keywords:
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- 1830 Groundwater/surface water interaction;
- HYDROLOGY;
- 1835 Hydrogeophysics;
- HYDROLOGY;
- 1886 Weathering;
- HYDROLOGY;
- 5109 Magnetic and electrical properties;
- PHYSICAL PROPERTIES OF ROCKS