Measurements and kernels for sourcestructure inversions in noise tomography
Abstract
Seismic noise crosscorrelations are used to image crustal structure and heterogeneity. Typically, seismic networks are anisotropically illuminated by seismic noise, a consequence of the nonuniform distribution of sources. Here, we study the sensitivity of such a seismic network to structural heterogeneity in a 2D setting. We compute finitefrequency crosscorrelation sensitivity kernels for traveltime, waveformenergy and waveformdifference measurements. In line with expectation, wave speed anomalies are best imaged using traveltimes and the source distribution using crosscorrelation energies. Perturbations in attenuation and impedance are very difficult to image and reliable inferences require a high degree of certainty in the knowledge of the source distribution and wave speed model (at least in the case of transmission tomography studied here). We perform singlestep GaussNewton inversions for the source distribution and the wave speed, in that order, and quantify the associated CramérRao lower bound. The inversion and uncertainty estimate are robust to errors in the source model but are sensitive to the theory used to interpret of measurements. We find that when classical sourcereceiver kernels are used instead of crosscorrelation kernels, errors appear in the both the inversion and uncertainty estimate, systematically biasing the results. We outline a computationally tractable algorithm to account for distant sources when performing inversions.
 Publication:

Geophysical Journal International
 Pub Date:
 February 2014
 DOI:
 10.1093/gji/ggt411
 arXiv:
 arXiv:1310.0857
 Bibcode:
 2014GeoJI.196..971H
 Keywords:

 Theoretical seismology;
 Wave scattering and diffraction;
 Wave propagation;
 Astrophysics  Earth and Planetary Astrophysics;
 Astrophysics  Solar and Stellar Astrophysics
 EPrint:
 19 pages, 12 figures, Geophysical Journal International