An aseismic tectonic movement and implications in case of displacement monitoring in mauntains

Two decades of monitoring in the forefront of the CSA Mine at the toe of Krusne Hory Mts. (NW Bohemia) brought about a chance to investigate not only stability problems but also deformations of natural origin. Data about deformations have been evaluated and interpreted. Different monitoring methods were used primarily to check up effects of mining to stability of adjacent mountainous fault slopes, and to secure safety in the mining operations. Two survey galleries driven to steep hills of Jezerka and Jezeri, opened an insight deep into the massif of crystalline rock, and to its behaviour as to deformation. Evidence regarding time deformations shows horizontal creep, and several episodic events of about half a year duration, some due to mining, then another one of natural origin only. This period of the year of 1994 provides clear indications of episodic movements that can be interpreted only as of natural tectonic origin, and apparently in no connection with seismicity. The event, apart from slope uplifts, is represented mostly by strain changes in the marginal zone of the mountains. Movements of this kind may interfere in different measurements designed to check crustal movements, which is discussed.