On the repeatability and consistency of three-component ambient vibration array measurements

摘要: Ambient vibration measurements with small, temporary arrays that produce estimates of surface wave dispersion have become increasingly popular as a low-cost, non-invasive tool for site characterisation. An important requirement these to be meaningful, however, is the temporal consistency and repeatability resulting spatial autocorrelation curve estimates. Data acquired within several European research projects (NERIES task JRA4, SESAME, other multinational experiments) offer chance investigate variability derived data products. The dataset analysed here consists repeated array measurements, years time elapsed between them. were conducted by different groups in seasons, using instrumentations layouts, at six sites Greece Italy. amplitude spectra locations dominant sources vary two each location. Still, analysis indicates this does not influence information, which stable neither influenced instrumentation nor analyst. frequency range over curves can reliably estimated depends on dimensions (minimum maximum aperture) used specific deployment, though, may accordingly experiments. relative contribution Rayleigh Love waves wavefield likewise change measurements. observed generally or below 50%, especially low values rural sites. Besides, visibility higher modes noise conditions. similarity measured are stable, mainly determined sub-surface structure, thus derive velocity information depth. Differences models same from independently curves—as studies—are consequently adequately explained uncertainties measurement part.