Limits and Benefits of the Spatial Autocorrelation Microtremor Array Method Due to the Incoherent Noise, With Special Reference to the Analysis of Long Wavelength Ranges

To examine the upper limit of analyzable wavelength ranges (upper wavelength, ULW) spatial autocorrelation (SPAC) method in microtremor surveys, we have derived a formula evaluating stochastic errors phase velocity estimate obtained by SPAC method. We then followed our previous paper to evaluate biases generated that come from presence incoherent noise so could discuss which is crucial factor determining ULW. As result, considered as factor. In consequence, proposed signal-to-noise ratio (SNR) and determine with effects compensated. used observed data validate above theory. Through validation procedure, an approximation equation , where NULW means ULW normalized array radius A constant. The parameter took value about 1/2 2 cases this study. Finally, additional simple analysis was executed, indicates not only limits but also can provide benefits: they are possibly for attenuation soils. survey traditional Okada (2003, https://doi.org/10.1190/1.9781560801740) be mobile tool very local at site interest (i.e., gaining high resolution), frequency suited earthquake engineering using seismic arrays short time observations.