Combined use of refraction seismic, MASW, and ambient noise array measurements to determine the near-surface velocity structure in the Selinunte Archaeological Park, SW Sicily

Carla Bottari,Gesa Maria Petersen,Klaus-G. Hinzen,Iris Schwellenbach

doi:10.1007/s10950-020-09909-4

Abstract

Seismic refraction, multichannel analysis of surface waves (MASW) and ambient noise array measurements using the wireless array analysis (WARAN) system were applied to acquire near-surface profiles of seismic velocities in the Selinunte Archaeological Park. This ancient city is famous for numerous temples, which according to the literature, were destroyed by at least two earthquakes in antiquity. The morphology of the archeological park is affected by two rivers which in combination with the temple remains suggests three study sites. We determined the subsurface velocity at these three locations as essential information for further studies of the response of the temple structures to earthquake ground motions. The stratigraphy of the site indicates that low-velocity layers might exist. Seismic refraction profiles with 69 m spread and 24 geophones were employed during the active seismic experiments. The measured P-wave velocities of the top two layers were used as a constraint during the inversion of dispersion relations from the MASW and WARAN data. The reliability of the velocity profiles was tested by forward calculation of synthetic seismograms. P-wave velocities which were not well constraint throughout the dispersion curve inversions were adjusted through suitable Poisson’s ratios based on the well constraint S-velocities. The combined use of the three different kinds of measurements and multi-mode interpretation of the dispersion curves revealed velocity profiles including low-velocity layers which are supported by de-amplification observed in ratios of horizontal and vertical components of noise spectra.

Highlights

Selinunte, one of the first Greek colonies located in south-west Sicily, is known for its large temple ruins
Since dispersion curves are less sensible to changes in vP and densities (e.g., Forbriger 2003b), the vS models were complemented with the seismic refraction results and considering the geological constraints
The P-wave velocity of the upper two layers were obtained by seismic refraction experiments and the S-wave velocities were derived by inversion of dispersion curves from multichannel analysis of surface waves (MASW) and ambient noise array measurements

Summary

Introduction

One of the first Greek colonies located in south-west Sicily, is known for its large temple ruins. Archaeoseismological researches have more recently confirmed the earthquake hypothesis (Guidoboni et al 2002; Bottari et al 2009) They identified two earthquakes, the first one that occurred between 370 and 300 B.C.E. and seems causative for the destruction of the temples in the western part of Selinunte and probably Temple R located on the Acropolis (Marconi personal communication). The second earthquake between 330 and 500 C.E. destroyed the temples on the Acropolis and the eastern side (Guidoboni et al 2002; Bottari et al 2009). There is no definite information about the conditions of the temples when the earthquakes occurred, according to Guidoboni et al (2002) and Bottari et al (2009), there is no doubt that two damaging earthquakes hit the site.

Results

Discussion

Conclusion