Article,
First Arrival Seismic Tomography (FAST) vs. PStomo\_eq applied to crooked line seismic data from Siljan ring area
Computers & Geosciences, 32 (4): 497--511 (May 2006)
DOI: 10.1016/j.cageo.2005.08.005
Abstract
When seismic profiles deviate significantly from straight lines, the
results from 2D traveltime inversion programs will be in error due
to the inherent 3D component present in the data. Thus, it is necessary
to use a program that can handle the 3D aspects of the acquisition
geometry. This study compares the performance and results from two
computer programs for 3D seismic tomography. These algorithms are
the package for First Arrival Seismic Tomography (FAST) and a Local
Earthquake tomography program, PStomo\_eq. Although both codes invert
for the velocity field using the conjugate gradient solver LSQR,
the common smoothness constraint is handled differently. In addition,
the programs do not incorporate the same options for user-specified
constraints. These differences in implementation are clearly observed
in the inverted velocity fields obtained in this study. Both FAST
and PStomo\_eq are applied to synthetic and real data sets with crooked
line geometry. First arrival traveltimes from seismic data acquired
in the Siljan ring impact area are used for the real data set test.
The results show that FAST gives smoother models than PStomo\_eq.
On the real data set PStomo\_eq showed a better correlation to the
information at hand. Different criteria exist for what is desirable
in a model; thus, the choice of which program to use will mostly
depend on the particular goals of the study.
