Love and Rayleigh waves inverted for vertical transverse isotropic crust structure beneath the Biga Peninsula and the surrounding area in NW Turkey.

The seismic speed and anisotropy are two methods frequently used to image the assembly inside the Earth. We study the crust assembly beneath the Biga Peninsula and the surrounding area in northwest Turkey using the accelerometer and broad-band recordings where short-to-medium period (5–20 s) Love–Rayleigh surface waves are utilized to extract the group-phase speed data (fundamental mode). Single-station and two-station techniques are engaged to understand the detected surface waves for the speed and anisotropy assemblies. The single-station group speeds are inverted in a tomographic approach to attain the 2-D group speed diagrams. The least-squares inversion procedure is utilized to find the speed–depth profiles (1-D) under each grid location. The 1-D results are cooperatively inferred to attain the 3-D appearance of the S -wave speeds below the measured region. This process is reiterated for Love and Rayleigh waves. Isotropic configuration is not sufficient to concurrently describe the present detected Love–Rayleigh surface waves. Vertical transverse isotropic crust assembly is found to better elucidate the detected data showing the Rayleigh–Love discrepancy. Complex arrangement of sills and dykes due to the widespread plutonic and volcanic activity in the region linked to the interaction between the Turkish plate and the African plate (northward subducting) is thought to depict the crust assembly deformations causing the detected long-wavelength vertical transverse isotropy. The mineral orientation within horizontal sills and vertical dykes following the magma flow, which is independent of seismic wavelength, adds to the detected anisotropy. The upper crust vertical transverse isotropy is mostly negative; that is, SV -wave is faster than SH -wave, which is assumed to be due to the existence of dykes. The middle-to-lower crust vertical transverse isotropy is commonly positive; that is, SH -wave is faster than SV -wave, which is assumed to be due to the existence of sills. The two-station analyses operating on cross-correlograms give analogous vertical transverse isotropic results to those of the single-station estimates. [ABSTRACT FROM AUTHOR]