Measurement of Surface-Wave Phase-Velocity Dispersion on Mixed Inertial Seismometer – Distributed Acoustic Sensing Seismic Noise Cross-Correlations

ABSTRACT The application of ambient seismic noise cross-correlation to distributed acoustic sensing (DAS) data recorded by subsurface fiber-optic cables has revolutionized our ability obtain high-resolution images the shallow subsurface. However, passive surface-wave imaging using DAS arrays is often restricted Rayleigh-wave and 2D along straight segments due intrinsic sensitivity being limited axial strain cable for most common type fiber. We develop concept estimating empirical surface waves from mixed-sensor velocity three-component seismometers strain-rate arrays. Using conceptual arguments synthetic tests, we demonstrate that these cross-correlations converge response at virtual single step forces applied seismometers. Rotating three orthogonal components seismometer a tangential–radial–vertical reference frame with respect each channel permits separate analysis Rayleigh Love medium sufficiently close 1D isotropic. also validate expressions facilitate measurement phase on far-field distances frequency–time analysis. These can be used records active sources local distances. recovery both in derived dark fiber array Sacramento basin, northern California, nearby permanent stations frequencies ?0.1–0.2 Hz, up ?80 km. phase-velocity dispersion measured are consistent those traditional pairs. Our results extend 3D Love-wave tomography surrounding array.