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| Titel |
Structure and evolution of collapse sinkholes: Combined interpretation from physico-chemical modelling and geophysical field work |
| VerfasserIn |
Georg Kaufmann, Douchko Romanov |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250103545
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| Publikation (Nr.) |
 EGU/EGU2015-2958.pdf |
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| Zusammenfassung |
| In karst rocks (limestone, anhydrite, gypsum, /¦), water flowing through fissures and
bedding partings can enlarge voids either by physical and/or chemical dissolution.
Within a geologically short period of time, the increase in void space creates a large
secondary porosity typical for soluble rocks, which is responsible for preferential
flow through the karst rock, often through cave systems with passages reaching the
meter-scale and more. This large-scale voids in the sub-surface can initiate collapse of the
overburden, either through wall or roof breakdown, and the initial void created by
dissolution can migrate upwards and finally cause a surface collapse and create a
collapse sinkhole. While the dissolution part of this evolution is in the order of
10,000-100,000 years, the final mechanical collapse can occur on time scales of
days.
We have studied the initiation of sub-surface voids with our numerical tool
KARSTAQUIFER, a 3D karst evolution model describing flow and dissolution in karst rocks.
We apply this numerical model to a typical collapse sinkhole site in the southern Harz
Mountains in Germany, with anhydrite as soluble rock in the sub-surface. We then discuss
geophysical measurements (gravity, electrical resistivity tomography, self potential,
magnetics) from the location to identify the local collapse sinkhole signal and the possibility
to separate the collapse sinkhole signal from the broader geological signal of the study
site. |
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