Commentary on “Once More about Deep Earthquakes in the Caucasus” by A.A. Godzikovskaya

Abstract

In 2016, V.Yu. Burmin with coauthors published the results of a new interpretation of the data from seismological bulletins on the territory of Armenia. In the reinterpretation, the initial data were thoroughly verified and discarded, and an original earthquake location algorithm developed by the author was used. The algorithm minimizes the functional of distances between points (X, Y, H) and (x, y, h) corresponding to theoretical t _i and observed ${\tilde t_{\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\cdot}$}}{i} }}$ travel times of seismic waves from earthquake sources to recording stations. As a result, it was found that, in addition to crustal earthquakes, deep earthquakes with a source depth of down to 300 km also occurred. This unconventional result has raised objections from some seismologists, which are stated in the work by A.A. Godzikovskaya, published in this issue of the journal. In present paper, we respond to the objections by A.A. Godzikovskaya. Among her main arguments is the difference in the form with which deep and crustal earthquakes are recorded. However, the form of recording depends not only on the source depth, but also on the velocity structure of the medium beneath the seismic station and the source mechanism, which determines the pattern of seismic energy radiation from the source, and on the duration of the faulting process in the source itself. The question of the typical form for recording seismic waves of earthquakes with different mechanisms and depths for this region requires special study.