Surface exposure dating of the Veliki vrh rock avalanche in Slovenia associated with the 1348 earthquake

Over 30 samples from bedrock and boulders from theVeliki vrh rock avalanche have been collected for surface exposure dating. The limestone rocks have been radiochemically treated to isolate and determine long-lived ³⁶Cl by accelerator mass spectrometry. It could be shown that the Veliki vrh rock avalanche from the Košuta Mountain (Slovenia) event can be very likely linked to one of the major historical Earth-quakes in Europe happening on the 25^th of January 1348. Taken into account independently determined denudation rates, inherited ³⁶Cl originating from pre-exposure at shallow depths (20-55 m) could be calculated. The high amount of inherited ³⁶Cl, i.e. 17-46% of the total ³⁶Cl, makes this site not suitable for a precise determination of the ³⁶Cl production rate as it was originally anticipated. Velikhi vrh is a “classic” rock avalanche of high velocity. The slope failed in the upper part with a translational slide, whereas dynamic fragmentation is the cause for further crushing of the material and the long runout.