Tectónica reciente y grandes avalanchas calcáreas en el arco externo de la Sierra de la Sobia (zona cantábrica, rama norte del varísco ibérico)

Abstract

A fault-damage zone belonging to western Sobia Range, parallel to the main trace of the León Line, has been mapped. Fractures across the limestone rock-mass are distributed according to sequential movements of conjugate systems. Their orientations are changing by the effect of the Sobia Nappe structure (Cantabrian Zone, NW Iberian massif) in the stress field distribution. Higher stresses are located in two different zones where the main fault attitude changes. Locally, the León hanging wall is formed by the Teverga coal basin, which is out sequence thrusting toward the NE. Both zones have several rock-avalanche deposits with planimetric surfaces reach 0.5 km2. Rockfault process has produced changes in the fluvial network. Moreover, the development of avalanche scarps and other minor structures are consistent with the recurrence of rock-avalanches and rockfall. Some of the late movements triggered recent rock fall over a small rural town, and reactivated the fracture system strike N090ºE as right lateral faults.