CONSTRAINTS ON LONG-TERM SEISMIC HAZARD FROM VULNERABLE STALAGMITES FOR THE SURROUNDINGS OF KATERLOCH CAVE, AUSTRIA

Abstract

The examination of a stalagmite in the Katerloch Cave (Austria) allows estimating an upper limit for horizontal peak ground acceleration generated by paleoearthquakes. The geometrical dimensions and the eigenfrequencies of an intact stalagmite were determined by in situ observations. The value of horizontal ground acceleration resulting in failure and the eigenfrequencies were assessed by theoretical calculations as well. The acceleration level determined by our study for the territory of Katerloch Cave is much lower than the PGA value interval (from 0.075 g to 0.1 g, in case of arithmetic mean, 85% fragile, rock type) determined by probabilistic seismic hazard calculation (SHARE Model) for a 475-year recurrence time (in 50 years with 10% probability of exceedance).