Evaluation of detection level of crustal deformation observation in the time domain through power spectrum analysis -Investigation of a long-baseline laser extensometer

We evaluated the crustal deformation detection level of a long-baseline laser extensometer in the time domain through the power spectrum from time-series data. The extensometer was newly installed in Hamamatsu City, Shizuoka Prefecture, Japan, and has a 200 m baseline. The detection level was compared with those of borehole multicomponent strainmeters and the GPS network evaluated in our earlier study, and also compared with noise levels of other laser extensometers. The power spectrum of the laser extensometer data shows a lower amplitude level by about 1006 and a frequency dependence similar to the average for borehole multicomponent strainmeters. The frequency dependence and amplitude of the noise level are comparable to those of long-baseline laser strainmeters in other regions. These results imply that the laser extensometer would detect the crustal deformation due to the Tokai long-term slow-slip event earlier than the GPS network.