Three large prehistoric earthquakes in the Eastern Alps evidenced by cave rupture and speleothem damage

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Publikace nespadá pod Fakultu sportovních studií, ale pod Přírodovědeckou fakultu. Oficiální stránka publikace je na webu muni.cz.
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BAROŇ Ivo PLAN Lukas GRASEMANN Bernhard MELICHAR Rostislav MITROVIĆ-WOODELL Ivanka ROWBERRY Matt SCHOLZ Denis

Rok publikování 2022
Druh Článek v odborném periodiku
Časopis / Zdroj Geomorphology
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Citace
www https://doi.org/10.1016/j.geomorph.2022.108242
Doi http://dx.doi.org/10.1016/j.geomorph.2022.108242
Klíčová slova Cave rupture; Active tectonics; Speleothem; Paleoseismology; Deep-seated gravitational slope deformation; Obir Caves; Eastern Alps
Popis Spectacular geomorphic evidence of recent tectonic activity and three potentially strong prehistoric earthquakes were discovered in Obir Caves in the Karawanken Mountains. This paper presents active fault structures, geomorphic features, and the age constraints attributed to particular seismotectonic events. The 1976 Mw 6.7 Friuli earthquake about 100 km from Obir Caves caused only local speleothem damage. The 100 km hypocentral distance enabled attenuation of the seismic waves so speleothem damage due to stalagmite resonance frequency was dampened. The documented dripstone column damage was rather caused by its sudden shortening due to passing elastic S-waves with estimated 3.5 (+8.2/-1.5) mm PGD amplitudes. At least three distinct seismotectonic events in the Late Pleistocene and Early to Middle Holocene were constrained by radiometric dating. The 40.6 cm sinistral fault slip occurred between 41.8 ± 1.3 ka and 18.7 ± 0.4 ka ago, the 2.6 cm dextral oblique reverse fault slip happened between 10.73 ± 0.23 and 8.61 ± 0.15 ka ago, and another speleothem damage event took place between 6.28 ± 0.24 ka and 5.7 ± 1.2 ka ago. These events were most probably accompanied by distinct destructive to very destructive paleoearthquakes with local intensities ranging from VIII to X on the ESI 2007 scale, significant rock weakening, and forming the large deep-seated gravitational slope deformation on the southeastern mountain slopes adjacent to Obir Caves.
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