APPLICATION OF THE RANDOM DECREMENT METHODFOR ESTIMATING SHEAR WAVE VELOCITY IN DEEPBASINS THROUGH CODA WAVES

Estimating shear wave velocity in deep basins always presents numerous challenges. This is due tothe inherent limitations in typical invasive methods, such as boreholes, including the need for drillinga large number of boreholes, limited penetration depth and difficulties associated with drilling in urbanareas. On the other hand, despite many applications in urban areas, non-invasive methods may face thechallenge of insufficient energy in the noise wavefield to effectively excite the very deep basinstructure.This paper reviews one of the most popular methods for retrieving shear wave velocity, based onthe random decrement method, the RayDec method. We introduce a novel approach for extractingellipticity using the coda part of earthquakes, which typically exhibit larger energy comparing to thenoise at low frequencies. Additionally, we briefly present a Python package designed to processseismic (and noise) data, enabling the extraction of coda waves and calculation of RayDec andRayDec on earthquake coda.The results for stations located mostly in the southern part of Tehran show highly consistentellipticities, suggesting the feasibility of employing this approach on a larger scale in other deep basinssuch as Japan, which have more extensive and precise earthquake data.

Keywords:

Coda Wave , Shear Wave Velocity , Sedimentary Basins , Ellipticity