Electrical Resistivity Imaging of Recent Landslides in Colorado Springs, Colorado, USA.

This article focuses on the use of electrical resistivity (ER) imaging to investigate the 2015 Skyway and Broadmoor Bluffs landslides in Colorado Springs, Colorado, USA. The study employed two-dimensional ER inverse modeling constrained by geological and borehole data, revealing that both landslides occurred within the weathered claystone portion atop the Cretaceous Pierre Shale, with failure surfaces at depths of 3–6 m for Skyway and 6–8 m for Broadmoor. The Pierre Shale exhibited low resistivity values indicative of high moisture content, which likely contributed to slope instability and landslide initiation. The landslides are characterized as rotational types, though most failure surfaces were irregular rather than smooth. These first subsurface geophysical models provide critical information for city planners to monitor and mitigate future landslide risks, especially during high-precipitation events, and highlight the need for additional geophysical studies to better understand landslide dynamics in the region.