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$\rm{ReMi^{TM}}$ (Refraction microtremor); seismic risk assessment; site characterization; $V_{s30}$; Isparta basin.

This study presents a site classification of the Isparta basin situated at the upper part of the Isparta Angle, which is one of the most important tectonic components in Turkey. The local conditions of the basin sediments may significantly increase ground motions from earthquakes and cause more structural damage. $V_{s30}$ is one of the base parameters used for the determining site classification. In this study, refraction microtremor ($\rm{ReMi^{TM}}$) method was used to determine the shear-wave velocities structure and hence classifying the site characterization of Isparta basin. The data were collected at 172 locations and converted to shear-wave velocity–depth models and shear velocity ($V_{s}$) maps were created. The $V_{s}$ structures were compared and evaluated with the current borehole records compiled from the area. The site classification map of the Isparta basin was prepared by using the $V_{s30}$ map and considering the National Earthquake Hazards Reduction Program (NEHRP) criteria. According to this map, the soft alluvial deposits of the central basin are mostly classified as D, and a few are classified as C. The soil class at the southern part of the basin (old urbanization area of the city) increases to C class due to which the tuff–tuffite content increases. The rock units such as Mesozoic carbonates and Cenozoic flysch located around the basin are classified as A. The soil class B, appears between the class A rocks and the alluvial basin, has relatively thin alluvial slope deposit overlying the rock. The classification obtained from this study may contribute to the studies on future urban planning and seismic risk assessment.

ALI SILAHTAR¹ MEHMET ZAKIR KANBUR² GuNAY BEYHAN¹

1. Department of Geophysical Engineering, Sakarya University, Sakarya, Turkey.
2. Department of Geophysical Engineering, Suleyman Demirel University, Isparta, Turkey.

Published

10 February 2020

Manuscript received

21 June 2018

Manuscript revised

4 July 2019

Accepted

10 October 2019

Early published

Unedited version published online

Final version published online

7 February 2020