Geofyzikální průzkum a datování sesuvu v údolí Javorné (Zlatohorská vrchovina)

Abstract

The newly identified Javorná landslide (GPS 50.2506 N, 17.3099 E) is located above the Javorná settlement (Jeseník District, the Olomouc Region, Czechia) about 0.5 km southeast of Bílý kámen Mt. (612 m a. s. l.) within the Zlaté Hory Upland. The landslide was geomorphologically mapped, dated using the radiocarbon method, and geophysical measurements using electrical resistivity tomography were carried out to interpret surface and subsurface structure of the landslide. It is a rotational rockslide developed in deluvium formed by rocks of the envelope of the Desná Unit (orthoquartzites > amphibolites, gneisses), covering an area of approximately 0.11 km2 (~ 400 × 300 m). Up to three headscarps were identified, including the uppermost amphitheatre-like, which is discontinuous and not very prominent. The most significant scarp borders the landslide on the north-east all the way to its toe. Central part of the landslide is undulated, with several zones of local shallow depressions. The largest temporary water area (sap pond) documented in spring 2023 in the southern part of the landslide is ca. 10 × 5 m large. The toe of the landslide reaches in places the Javorná Stream, and it is possibly partially eroded. Frequent springs were noticed in front of the headscarp of the landslide. The resistivity profile through the landslide shows the maximal thickness of the landslide body to be 16 m in the lower part of the slope. The body of the landslide is characterized by the zone of higher resistivity values with sharp shear surface which is clearly visible from the resistivity data. Radiocarbon dating of the sedimentary fill of the intracolluvial depression determined the minimum age of the landslide to be 2760 to 3290 ± 30 years BP.