Karst cavity detection in carbonate rocks by integration of high resolution geophysical methods

Volume 15 , Issue 1 , December 2013 , Pages 159-171

Authors

¹ Faculty of Science and Education, University of Sulaimani

² Faculty of Humanitarian Science, University of Sulaimani

Combined surveys using Ground Penetrating Radar (GPR) and Electrical Resistivity

Tomography (ERT) are deployed to provide a cost effective characterization of the

subsurface karst environments. A total of 12 GPR traverses and 4 ERT lines with lengths

from 140 to 710 m are conducted at Sulaimani governorate, NE Iraq (45o 04' E and 35o 35'

N). The area represents a broad syncline of limestone rocks, which is covered by a thin

layer of recent sediments. Great anomaly depicting crest (high) like pattern was noticed on

GPR records. A plausible interpretation for this anomaly was a cavity filled either by

groundwater or by residual products of karstification. The presence of this cavity was

confirmed also by electrical resistivity tomography. An excellent correlation exists

between GPR signatures and ERT layers. The extension and the depth to the top of the

cavity were determined from both GPR data and 2D inversion interpretation. A huge cave

was discovered. It is located at depth of 25.0 meters. It has an elongated shape that extends

from southeast to northwest direction. The geophysical survey results show this cave with

approximate dimensions of 150.0 m long, 35.0 m wide and 24.0 m high.

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