Towards global earth tomography using the spectral element method: A technique based on source stacking
Journal
Geophysical Journal International
Journal Volume
162
Journal Issue
2
Pages
541-554
Date Issued
2005
Author(s)
Abstract
We present a new tomographic method based on the non-linear least-squares inversion of seismograms using the spectral elements method (SEM). The SEM is used for the forward modelling and to compute partial derivatives of seismograms with respect to the model parameters. The main idea of the method is to use a special data reduction scheme to overcome the prohibitive numerical cost of such an inversion. The SEM allows us to trigger several sources at the same time within one simulation with no incremental numerical cost. Doing so, the resulting synthetic seismograms are the sum of seismograms due to each individual source for a common receiver and a common origin time, with no possibility to separate them afterward. These summed synthetics are not directly comparable to data, but using the linearity of the problem with respect to the seismic sources, we can sum all data for a common station and a common zero time, and we perform the same operation on synthetics. Using this data reduction scheme, we can then model the whole data set using a single SEM run, rather than a number of runs equal to the number of events considered, allowing this type of inversion to be feasible on a reasonable size computer.
Type
other