Quantifying near fault pulses using generalized Morse wavelets

Abstract

Recently, a family of analytic wavelets known as generalized Morse wavelets (GMW) has been established in the literature. This versatile wavelet family uses two parameters (γ and β) to adjust its frequency or time domain properties. By varying these two parameters, this wavelet family includes many commonly used analytic wavelets. In this paper, GMW are examined, along with the continuous wavelet transform (CWT), to determine their suitability for extraction of ground motion pulses from a suite of acceleration records. GMW are compared to a popular pulse model that has recently been adapted for wavelet analysis in the literature. It is shown, based on two different metrics, that GMW performs comparably with the other model for this suite of ground motions. Since CWT is repeated with different wavelet parameters for each ground motion, the parameter selection and pulse extraction process are examined. It is shown that using the maximum wavelet coefficient alone does not allow for the extraction of pulses that best match the time series or the spectral response. Alternative criteria are proposed in order to optimize pulse selection using performance-based metrics.