6th Colloquium on historical earthquakes & paleoseismology studies

Did seismic shocks damage speleothems in Central Carpathian caves?

24 Oct 2018, 13:45

35m

Han-sur-Lesse

Poster Preference Session 4 Posters Poster Session 1

Speakers

Dr Jacek Szczygieł (Department of Fundamental Geology, Faculty of Earth Sciences, University of Silesia) Wojciech Wroblewski (Institute of Geological Sciences, Jagiellonian University)

Description

Seismic activity has been instrumentally recorded in the Central Western Carpathians, both in Slovakia and Poland. Many earthquakes were registered in ancient written sources, such as chronicles. Compilation of instrumental data and historical sources shows that epicenters of earthquakes are clustered in zones, which is an expression of the regional faults pattern. Several seismically active zones had been distinguished in the Central Western Carpathians and this mountain chain was regarded as the ‘shallow crustal active region’. Seismic events in the Carpathians result from neotectonic processes that are associated with the collision of the ALCAPA microplate with the European plate. The history of the seismicity in the Central Western Carpathians has so far been based solely on instrumental record and historical data. The study of speleothems may lead to unraveling the Middle Pleistocene to Holocene seismic history of the Central Western Carpathians. This area abounds with caves where naturally damaged speleothems occur. Although some data suggest ice and frost action as the reason for speleothem destruction, the involvement of seismic activity is one of the possible causes of such damage. The present study concentrates on naturally damaged speleothems, especially: (i) fractured and broken speleothems, (ii) tilted stalagmites, (iii) displaced pairs of stalactite-stalagmite, (iv) collapsed parts of ceiling including speleothem overgrowths (flowstones and stalactites), (v) fallen stalactites (including fragile soda-straw ones), (vi) layers with angular debris and broken speleothems cemented within flowstones. Preliminary results provide some examples which support the idea of involvement of seismic activity in destruction of speleothems. Study of speleothems in the Tatra Mts. may serve as one meaningful example. Speleothem destruction and their subsequent regrowth took place there ssynchronously ca. 95 ka. This period is regarded as relatively warm, thus deep frost action as a causing mechanism can be ruled out. Another example is the 32 m tall stalagmite in Krásnohorská Cave (the Slovak Karts area), one of the highest stalagmites known worldwide. The stalagmite is severed; its former summit is collapsed and wedged in the cave passage near its bottom. A huge earthquake seems to be most probable cause of this damage. Precise dating of damaged speleothems in the Central Western Carpathians caves, preceded by a careful selection of samples for dating, should have a great potential to expand the chronology of seismic activity in this area back to the geological history. The research project no. 2017/25/B/ST10/01430 is financed from the funds of the Polish National Science Center.