LAUSR

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 temporarily installed two small arrays to obtain simultaneous records of vertical microtremors. 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.