OpenHVSR: Processing Toolkit and Inversion; Two Computer Programs engineered for the complete workflow of the Horizontal-to-Vertical Spectral Ratio (HVSR) Method and for the Investigation of Lateral Variation of the Informative Content of Data

*Corresponding Author

Abstract

The Horizontal-to-Vertical Spectral Ratio technique (HVSR) has become extremely popular. Nowadays, since microtremor measurements are fast to perform and equipment extremely portable, the typical HVSR dataset comprises a multitude of single-station acquisitions distributed over a geographical area. Availability of such datasets triggered an increasing interest in spatially correlating informative content from HVSR at different locations. The OpenHVSR project developed following this perspective and nowadays it comprises two different computer programs, both open source, and developed in Matlab.

The first program, published in 2016, “OpenHVSR-Inversion”, has been implemented to enhance the inversion of HVSR curves. Its purpose is the inversion of large HVSR datasets and provide a 2D and 3D visualization of results, so to promote a better understanding of the local geology.

The second program (June 2018), "OpenHVSR-Processing Toolkit" is devoted to the signal processing necessary to compute HVSR curves from field data. It is engineered to enhance single-station microtremor processing with the purpose of spatially correlating different forms of informative content, maps creation, and display of the results in 2D/3D. In particular, since all the tasks are performed in the same package, the map creation bottleneck, historically constituted by the combined use of several software is avoided and changes in processing choices immediately reflects on the result without the need of starting from scratch. We aimed at including the most desirable tools present in other software, all in one bundle. In addition, we have integrated several original features that are not present in any other program. Further, bedrock mapping capability (Ibs-von Seht and Wohlenberg, 1999) is included both through the computation of bedrock depth via a set of published regressions or by computing a customized regression based on the information at hand.

OpenHVSR-Processing-Toolkit naturally integrates the inversion software OpenHVSR–Inversion. Together, they constitute a complete workflow for the HVSR method.

We expect this programs to be of great use to researchers and we hope they will constitute the basis for further collaborative developments oriented at exploring the full potentials of this technique.