Affiliations: [a] Institute of Earth Sciences, University of Iceland, Sturlugata 7, 101 Reykjavik, Iceland. t.a.smaglichenko@gmail.com, {tanya,ingib,alexand}@hi.is | [b] Institute of Earth Sciences, Johannes Gutenberg University Mainz, D 55099 Mainz, Germany. jacoby@uni-mainz.de
Correspondence:
[*]
Address for correspondence: Research Oil and Gas Institute of Russian Academy of Sciences, Gubkina 3, 119333 Moscow, Russia. Reporter. Now: Research Oil and Gas Institute of Russian Academy of Sciences, Moscow, Russia.
Note: [†] Now: Institute of Seismology and Geodynamics, V.I. Vernadsky Crimean Federal University, Vernadskogo Prospekt 4, 295007 Simferopol, Republic of Crimea.
Abstract: The changes in the state of a geophysical medium before a strong earthquake can be found by studying of 3D seismic velocity images constructed for consecutive time windows. A preliminary step is to see changes with time in a minimum 1D model. In this paper we develop a method that finds the parameters of the minimum linear gradient model by applying a two-dimensional Taylor series of the observed data for the seismic ray and by performing least-square minimization for all seismic rays. This allows us to obtain the mean value of the discrete observed variable, close to zero value.
Keywords: local earthquake tomography, minimum 1D model, linear gradient of velocity
