Microtremor Array Measurements for Shallow S-Wave Profiles at Strong-Motion Stations in Hatay and Kahramanmaras Provinces, Southern Turkey by Özgür Tuna Özmen, Hiroaki Yamanaka, Mehmet Akif Alkan, Ulubey Çeken, Taylan Öztürk, and Ahmet Sezen Abstract We conducted microtremor array exploration of shallow S-wave velocity profiles at 28 sites in Hatay and Kahramanmaras, in the southern part of Turkey, to provide fundamental data to assess seismic hazards in the two areas. A total of 16 and 12 sites were located in Hatay and Kahramanmaras Provinces, respectively. We tem- porarily installed two small arrays to obtain simultaneous records of vertical micro- tremors. The spatial autocorrelation method was applied to retrieve Rayleigh-wave phase velocity in a 1–30 Hz frequency range. The phase velocities at most of the sites in Kahramanmaras Province were high in the entire frequency range, whereas those in Hatay Province were widely distributed, suggesting significant variation in soil conditions. Low-phase velocities were identified at sites near the coast in Hatay. Subsequently, the phase velocity observed at each site was inverted to a 1D S-wave velocity profile to a depth of 100 m using a hybrid heuristic inversion. Most of the profiles in Kahramanmaras had very thin near-surface layers with S-wave velocities of less than 300 m= s and thicknesses of less than 10 m. The top layers at the sites in Hatay showed significant variation, with different S-wave velocities from 110 to 760 m= s and thicknesses from 2 to 40 m. These layers were thicker at the sites near the coastal area. We finally discuss amplification factors of S waves using the inverted profiles. The fundamental predominant periods of the amplification factors distributed across a wide frequency range from 0.8 to 10 Hz in Hatay. The peak frequencies concentrated in a high-frequency range of more than 5 Hz in Kahramanmaras. The profiles observed were used to map average S-wave velocities in the top 30 m at strong-motion stations. Introduction The south-central part of Turkey is located in the triple junction of the Arabian, African, and Eurasian plates. The major tectonic faults, North Anatolian fault zone (NAFZ) and East Anatolian fault zone (EAFZ), exist in the area (Fig. 1). Because of this tectonic setting, the central-southern part of Turkey is known as an area with high seismicity. Several destructive earthquakes have hit the area and caused serious damage. In particular, heavy damage was experi- enced in the Hatay area during large earthquakes in 1822 and 1872 (Tarı et al., 2013). The most recent heavy-damage earthquake (M 5.5, 22 January 1997) occurred in Antakya to the City center of Hatay. For this reason, seismic-hazard estimation for future earthquakes is an important issue in the central and local governments in the area. Accordingly, several microzonation maps have been proposed (e.g., Över et al., 2011). One of the important factors involved in the establishment of a seismic microzoning is an appropriate estimation of effects of local geological condition. These effects are usually estimated using S-wave velocity data for soils. However, S-wave velocities have not been adequately explored in terms of seismic-hazard estimation in this area. Site amplification in the area was estimated with actual data from earthquake observation, borehole data, microtre- mor surveys, and surface-wave surveys. Över et al. (2011) conducted microtremor measurements for horizontal-to- vertical (H/V) ratio and surface-wave exploration for Rayleigh- wave phase velocity to deduce shallow S-wave velocity profiles in Antakya, Hatay Province. Akkar et al. (2009) and Sandikkaya et al. (2010) revealed S-wave velocity profiles at 236 strong-motion stations of the Prime Ministry Disaster and Emergency Management Authority (AFAD) across the whole of Turkey using surface-wave exploration and bore- hole surveys, including 8 and 11 stations in Kahramanmaras BSSA Early Edition / 1 Bulletin of the Seismological Society of America, Vol. 107, No. 1, pp. –, February 2017, doi: 10.1785/0120160218