hvsrpy: An Open-Source Python Package for Microtremor and Earthquake Horizontal-to-Vertical Spectral Ratio Processing

Abstract Since its empirical discovery over 30 years ago, the horizontal-to-vertical spectral ratio (HVSR) has become one of, if not, the most popular techniques for noninvasive site characterization with users spanning the fields of seismology, geophysics, and engineering. The size of the HVSR community has resulted in a broad range of perspectives on how HVSR data should be processed. Unfortunately, HVSR processing software has focused on providing users the tools to perform one specific processing workflow, with no software having yet been developed that is capable of accounting for the breadth of perspectives in the HVSR community. In response, this work presents a new release of the open-source Python package hvsrpy designed to provide users a simple, extensible, and reproducible tool for microtremor and earthquake HVSR processing. hvsrpy provides a comprehensive set of features not available in any other open source or commercial software. These features include: parsing of microtremor and earthquake seismic records in all common file formats (seven in total), processing of ambient noise using the traditional multiwindow, azimuthal, and diffuse wavefield approaches, combining the horizontal components using all common methods (seven in total), smoothing of Fourier spectra using all common methods (seven in total), removing low-quality HVSR windows using time- or HVSR-domain approaches (four in total), quantifying rigorous statistical measures, and computing power spectral densities as a diagnostic tool. Version 2.0.0 of hvsrpy provides a versatile HVSR processing software built to enable future processing standardization and scientific reproducibility.