SYSTEMATIC-ERRORS IN SEISMIC CROSSHOLE DATA - APPLICATION OF THE COUPLED INVERSE TECHNIQUE

Systematic errors in seismic travel-time data from mis-located and/or systematic timing delays can distort considerably the results of tomog raphic inversions. Standard crosshole tomographic inversion algorithms do not account for systematic errors. Given sufficient data redundanc y, the coupled inverse technique allows velocities, source and receive r coordinates and systematic delays to be reliably determined. Efficie ncy of a coupled inverse technique in crosshole applications is demons trated through inversions of synthetic data sets and calculations of t he formal resolution matrix. Tests revealed that shot delays may trade off with shot coordinates, but neither coordinates nor delays show st rong dependencies or correlations with velocity parameters.