On 3 February 2002, at 09 h 11 min 28 sec GMT the small townships of Sultandaðý, Çay and Bolvadin southeast of Afyon in southwest Turkey were shaken by a destructive earthquake (Fig.1) which was strongly felt in the surrounding cities such as Konya, Ankara, Eskiþehir, Kütahya and Isparta. During the earthquake 46 lives were lost, 318 persons were wounded and 622 buildings were moderate to heavily damaged. The township Çay was recorded to experience the heaviest damaged, followed by Sultandaðý and Bolvadin. In rural areas the intensive damage was recorded in the villages surrounding the the townships Çay and Sultandaðý.
The earthquake is a result of the reactivity of Sultandaðý fault which was shown on the Active Fault Map of Turkey prepared and published by General Directorate of Mineral Research and Exploration (MTA) of Turkey in 1992. The former earthquake (Ms=5.8) in the area was recorded on the western termination of this fault zone, in Çobanlar area, on 15 December 2000.
A group of researchers of the Natural Disaster Research Unit of Geological Research Department of MTA passing to the earthquake area on 4 February 2002 upon the direction of the Director General and has prepared the following preliminary report after a field work of eight days. The report aims to give general information on the earthquake itself and the surface ruptures related. During the field work some difficulties were faced in systematic data collection due to the unfavourable conditions resulted from diurnal freezing and thawing, and snow cover on the ground in regions where the surface ruptures observed as micro cracks. Further research is being carried out on the detailed geometry of faulting and on the setting of the earthquake in the regional active tectonics.
TECTONIC SETTING AND THE SULTANDAÐI FAULT
Sultandaðý earthquake occurred on the northern end of the Isparta bend which holds a significant place in the neotectonic structure of Turkey hampering the westerly escape of Anatolian block. Isparta bend is bounded by the Sultandaðý fault in its north-northeastern front. In the Active Fault Map of Turkey prepared and published by MTA in 1992 the Sultandaðý fault was described as a reverse active fault. The Afyon-Akþehir basin that was shaped relevant to the movement of the Sultandaðý fault is the easternmost section of the graben structures that developed related to the Aegean extensional tectonic regime (Koçyiðit et al., 2000). The Sultandaðý fault traced between the Sultandaðý rise and the graben basins to the east and north of it has an approximate length of 100 km on the Active Fault Map of Turkey (Fig.2). When the Afyon graben related to the fault is included, the length of the fault reaches up to 150 km. The Sultandaðý fault is a low-angle normal fault. The main fault lies in a zone of tens of meters to a few kilometers. Morphotectonic data suggests that the vertical displacement exceeds 1000 m in its northern end around Çay. The 3 February 2002 earthquake occurred on the northwestern end of the fault. During the surface rupture mapping indications on the Holocene activity of the fault in some locations were observed. Fault scarps and deformations in Holocene sediments related to the previous earthquakes are obvious in the area.
The grabens situated in Sultandaðý region form a significant seismogenic zone in Turkey. Intensive microseismic activity and three earthquakes M>5 were recorded in the area, namely, 1921 Argýthaný (M=5.4), 1946 Argýthaný (M=5.5) and 15 December 2000 Çobanlar (Mw=6.0) earthquakes (Ambraseys, 1988, Taymaz and Tan, 2001). The first two of these occurred on the southern termination of the fault, whereas the latest event took place on the northern termination. It can be said that, from historical point of view, 3 February 2002 Sultandaðý earthquake occurred on the Çay segment, filling a seismic gap.
SEISMOLOGIC DATA
The main shock of Sultandaðý earthquake was recorded as Ms=6.5 (USGS) on 03 February 2002 at 09 h 11 min 28 sec GMT followed by intensive aftershocks (Fig.3). Two hours after the main shock another event of Ms=5.6 (USGS) occurred and collapsed the buildings damaged during the main shock. The data on the main shock and the second event collected from various sources were given at Tables 1 and 2, respectively. Epicentral location for the main shock is north of the township of Sultandaðý according to USGS, Kandilli Observatory and Swiss Seismological Service (ETHZ). Harvard University Seismology Group locates the epicenter of the main shock north of township of Çay. The epicentral locations for the second event are at the western continuation of the Sultandaðý fault. Fault plane solutions for both events reflect normal faulting (Fig.2 ). The epicentral location for the second event is very close to that of 15 December 2000 Çobanlar earthquake which also is a normal fault according to fault plane solutions.
Table 1. Seismologic data of the Sultandaðý earthquake from various sources (KOERI: Boðaziçi University Kandilli Observatory; DAD: Gen. Dir. of Disaster Affairs Earthquake Research Dept.; USGS: United States Geological Survey; HARVARD: Harvard University Seismology Group, ETHZ: Swiss Seismological Service).
