Retrieval of Rayleigh wave ellipticity from ambient vibration recordings- Introducing CVRD method
عنوان دوره: نوزدهمین کنفرانس ژئوفیزیک ایران
نویسندگان
1دانشجوی دکتری دانشگاه تهران
2موسسه ژئوفیریک
چکیده
Seismic noise is nowadays widely used in geophysics being easy and non-invasive techniques to characterize the subsoil structure. Different single and array methods have been introduced in this field to study seismic noise characteristics. RayDec as a single station method estimates the ellipticity curve of Rayleigh wave by stacking the time blocks of the signal with respect to the Random Decrement (RD) condition. In this study, we propose Vector Random Decrement (VRD) technique to obtain the ellipticity curve for a large number of stations recorded simultaneously in the array. The VRD technique benefits using vector triggering condition which forces every component of the array stations satisfy the common triggering points. We named the method as Common Vector Random Decrement (CVRD) technique in which common triggering points of all vertical components are used to determine the ellipticity curve of the array. In order to verify the method, an array data set is simulated. The synthetic and the real array data recorded in Ramsar site (North of Iran) are used to study the method. The results are compared with ones obtained from WaveDec array method. The CVRD method yields good performance in recognizing the singularities and right flank of fundamental mode of Rayleigh waves.
کلیدواژه ها
 
Title
Retrieval of Rayleigh wave ellipticity from ambient vibration recordings- Introducing CVRD method
Authors
Naimeh Sadat Moghadasi, Elham Shabani
Abstract
Seismic noise is nowadays widely used in geophysics being easy and non-invasive techniques to characterize the subsoil structure. Different single and array methods have been introduced in this field to study seismic noise characteristics. RayDec as a single station method estimates the ellipticity curve of Rayleigh wave by stacking the time blocks of the signal with respect to the Random Decrement (RD) condition. In this study, we propose Vector Random Decrement (VRD) technique to obtain the ellipticity curve for a large number of stations recorded simultaneously in the array. The VRD technique benefits using vector triggering condition which forces every component of the array stations satisfy the common triggering points. We named the method as Common Vector Random Decrement (CVRD) technique in which common triggering points of all vertical components are used to determine the ellipticity curve of the array. In order to verify the method, an array data set is simulated. The synthetic and the real array data recorded in Ramsar site (North of Iran) are used to study the method. The results are compared with ones obtained from WaveDec array method. The CVRD method yields good performance in recognizing the singularities and right flank of fundamental mode of Rayleigh waves.
Keywords
Ambient noise, ellipticity curve, RayDec method, Vector Random Decrement (VRD) technique