CALAS: Carpathian laser strainmeter - a project and preliminary results

A laser strainmeter for in-situ monitoring of an important actively seismic area of Europe, namely Vrancea region in Romania is proposed. Six groups from four different countries (Romania, Czech Republic, Italy and Greece) with various areas of expertise (e.g. geophysics, lasers, optics, interferometry, and mechanics) are involved in order to sustain the complexity of the project. This paper presents some preliminary laboratory experiments related to measuring relative displacements with a stable interferometer. Displacements of the order of tens to hundreds of nanometers (80 to 285 nm) were measured with uncertainty of ±1 nm. A computer algorithm was used to process the interferograms