The OpenHVSR Project
The OpenHVSR Project is a personal initiative. Initiated in 2015, slowly grew to a full research project. Despite the project developed with negligible funding, it now comprises two different computer programs, both developed in matlab and dedicated to the complete investigation of microtremors. Tipically single-station microtremor data are recorded at sparse locations over a geographical area. For each measurement, a spectral ratio curve is obtained. HVSR curves can be inversted in order to infer the subsurface vertical variation of visco-elastic properties under the recording station.
The first program I published in 2016 as open source, named OpenHVSR, has been implemented to enhance the inversion of HVSR (Horizontal to vertical component spectral ratio). The purpose of OpenHVSR, besides the inversion of large datasets, is to provide a 2D and 3D visualization of the inversion results, so to promote a better understanding of the local geology.
The second program I published (2018) and named "OpenHVSR-Processing Toolkit" is devoted to the signal processing necessary to compute HVSR curves starting from the microtremor data.
It is specifically engineered to enhance single-station microtremor processing with the purpose of spatially correlating different forms of informative data content, fast map creation, and display of the results in 2D and 3D. In particular, the map creation is made extremely flexible. Traditionally, to create a map of the resonant frequency (for example), required the combined use of several softwares. The task is now performed within the same software. As a consequence, work speed is dramatically improved and if a change in processing parameters is necessary, the effect of the change can be immediately evaluated, without the need of starting from scratch.The program aims at implementing the most effective and desirable processing tools present in other commercial and non-commercial alternatives, all in one bundle, freely available to the scientific community. In addition to incorporating and enhancing currently available state of the art tools, we have integrated several original features that are not present in any other program. Further, bedrock mapping capability, as introduced by 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 data at hand.
OpenHVSR-Processing-Toolkit (2018) naturally integrates the inversion software OpenHVSR (2016). Together, they constitute a complete workflow for the Horizontal-to-Vertical Spectral Ratio method.
I expect this first version to be of great use to researchers and hope it will constitute the basis for further collaborative development toward future releases oriented at exploring the potentials of this technique.
Programs are available here: