Two‐dimensional resistivity imaging: a tool in archaeoseismology. An example from ancient Sagalassos (Southwest Turkey)

Abstract

AbstractThe ancient Pisidian town of Sagalassos (southwest Turkey) was struck by several earthquakes during Roman and early Byzantine times and was abandoned around the middle of the seventh century AD, partly as the result of a devastating earthquake. A nearby epicentre is postulated, although the causative fault has not yet been identified. The identification of such an active fault is, however, important with respect to the assessment of the seismic hazard of the area. Two‐dimensional resistivity imaging has been used to detect the presence of an active normal fault passing underneath Sagalassos, as evidenced by geological, geomorphological and archaeoseismological observations. The resistivity profiles reveal the presence of five stratigraphical layers, i.e. from bottom to top: the bedrock composed of either limestone or ophiolitic me lange, the weathered top of this bedrock, old colluvial material, recent colluvial material that covers archaeological structures and recent scree deposits. The presence of active normal faults is, moreover, indicated by the displacement of the bedrock and the colluvial material on top of it. Offsets of archaeological structures at Sagalassos are likely to be the result of historical reactivations of these faults. The limestone front, overlooking Sagalassos from the north, probably corresponds to the degraded fault plane of the detected fault zone. Sagalassos was thus built on the hanging wall of an active normal fault. Two‐dimensional resistivity imaging proved to be an efficient tool in archaeoseismology. Copyright © 2003 John Wiley & Sons, Ltd.