An integrated geological and archaeoseismological approach of the seismicity in the territory of Sagalassos (SW Turkey). Towards the identification of active faults in the Burdur-Isparta region.

status: publishe

Two-dimensional Resistivity Imaging:a Tool in Archaeoseismology.An Example from Ancient Sagalassos (Southwest Turkey)

The 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. © 2004 John Wiley & Sons, Ltd.status: publishe

Different stress states in the Burdur-Isparta region (SW Turkey) since Late Miocene times: a reflection of a transient stress regime

The Burdur-Isparta region is a transitional zone between two distinct neotectonic domains in Turkey: the Burdur graben system as the northeastern part of the Fethiye-Burdur fault zone and the Kovada graben at the apex of the Isparta angle. Each domain represents a particular stress regime. Fault data from unconsolidated Pliocene and Quaternary deposits were combined with stress states deduced from pre-Pliocene consolidated rocks in order to reconstruct the stress field evolution in the study area since Late Miocene. Different stress states were identified. They were put in a stratigraphic framework and U/Th dating of fault-related calcite precipitates proved to be an additional tool in constraining the history of the stress states. The reconstructed history reflects a transient stress regime. The evolving stress field indicates that the influence of the Kovada stress regime fades through time and that the influence of the Burdur stress regime is gaining importance, suggesting a northeastwards progression of the Fethiye-Burdur fault zone. (c) 2006 Elsevier Ltd. All rights reserved.status: publishe

Testing diagnostic geomorphological criteria of active normal faults in the Burdur-Isparta region (SW Turkey)

status: publishe

Seismic catastrophes at the ancient city of Sagalassos (SW Turkey) and their implications for seismotectonics in the Burdur-Isparta area

The ancient city of Sagalassos, situated c. 10 km south of Isparta (SW Turkey), is located on the southeastern outskirts of an area affected by a number of large earthquakes (Ms > 6.0) in the last century, and where a number of seismogenic faults are identified. Archaeological relics at Sagalassos show ample evidence that the city experienced severe earthquake damage early in the sixth century AD and in the middle of the seventh century AD. This last seismic catastrophe even seems to have caused the abandonment of the city. It is postulated that the city was situated in the macroseismic epicentre, although the causative fault has not yet been identified. Based on satellite imagery, and both geological and geomorphological field evidence in the region of Sagalassos, NE-SW-trending and ENE-WSW-trending tectonic lines are considered as candidates for the seismogenic faults that caused the devastating earthquakes. Copyright (C) 2003 John Wiley Sons, Ltd.status: publishe

Identification of a historical morphogenic earthquake through trenching at ancient Sagalassos (SW Turkey)

The Sagalassos Fault is one of the candidate faults for the devastating earthquakes that struck the ancient Pisidian town of Sagalassos, situated some 10 km SSW of Isparta (SW Turkey), early in the 6th century A.D. and in the middle or (luring the second half of the 7th century A.D. The Sagalassos Fault is an at least 150-m wide and similar to 10 km long active normal fault zone, passing through and behind the ancient town. The southern base of the limestone cliff at the northwestern extremity of Sagalassos is believed to represent the strongly degraded master fault. The Sagalassos Fault Necropolis-trench, exposing this limestone face and its hanging wall deposits, reveals a fresh normal fault slip plane. Fault breccia, dip-slip frictional-wear striae, tool tracks, spall marks, dilational fractures and a flowstone are present on the excavated limestone face. Moreover, in the excavated part of the hanging wall, evidence of historical reactivation of the main fault has been inferred within anthropogenic deposits. The main argument is a 20-cm thick shear zone against the limestone face. This shear zone affects a man-made dump of the Early Imperial Period (ca. 25 B.C.-100 A.D.). The shear zone has an indurated and compact aspect, a parallel alignment of ceramic and limestone fragments, dip-slip striae and a vertical displacement of layers within the dump. The new findings of this study suggest that the surface-rupturing event identified may very well correspond to the 6th or 7th century earthquake, thus identifying a to date unknown seismically active and potentially hazardous fault in the Burdur-Isparta area. (c) 2005 Elsevier Ltd. All rights reserved.status: publishe

An integrated neotectonic study of the Çanakli basin (SW Turkey): remote sensing, surface geology and near-surface geophysics

status: publishe

Origin of palaeofluids in a normal fault setting in the Aegean region

The province of Burdur (SW Turkey) is seismically an active region. A structural, geochronological, petrographical, geochemical and fluid inclusion study of extension veins and fault-related calcite precipitates has been undertaken to reconstruct the palaeofluid flow pattern in this normal fault setting in the Aegean region. A palaeostress analysis and U/Th dating of the precipitates reveals the neotectonic significance of the sampled calcites. Fluid inclusion microthermometry of calcites-filling extension veins shows final melting temperatures (T-m ice) of 0degreesC. This indicates pure water, most likely of meteoric origin. The oxygen isotope values (-9.8parts per thousand to -6.5parts per thousand VPDB) and the carbon isotopic composition (-10.4parts per thousand to -2.9parts per thousand VPDB) of these calcites also show a near-surface meteoric origin of the fluid responsible for precipitation. The microstructural characteristics of fault-related calcites indicate that calcite precipitation was linked with fault activity. Final melting temperature of fault-related calcites ranges between 0 and -1.9degreesC. The oxygen isotope values show a broad range between -15.0parts per thousand and -2.2parts per thousand VPDB. Several of these calcites have a delta(18)O composition that is higher or lower than the oxygen isotopic composition of meteoric calcites in the area (i.e. between -10parts per thousand and -6parts per thousand VPDB). The delta(13)C Composition largely falls within the range of the host limestones and reflects a rock-buffered system. Microthermometry and stable isotopic study indicate a meteoric origin of the fluids with some degree of water-rock interaction or mixing with another fluid. Temperatures deduced from microthermometry and stable isotope analyses indicate precipitation temperatures around 50degreesC. These higher temperatures and the evidence for water-rock interaction indicate a flow path long enough to equilibrate with the host-rock limestone and to increase the temperature.status: publishe