On earthquake depths in the Crimean-Black Sea region

 

V.E. Kulchitsky¹, B.G.Pustovitenko^{1, 2}, V.A. Svidlova²

 

¹Crimean Expert Council on Seismic Hazard Assessment and Earthquake Prediction,
Simferopol, Republic of Crimea, Russia

 

²Institute of Seismology and Geodynamics of the Vernadsky Crimean Federal University,
Simferopol, Republic of Crimea, Russia

 

Corresponding author: Bella G. Pustovitenko, e-mail: bpustovitenko@mail.ru

 

Abstract. The problem of determining the earthquake source depth in the Crimean-Black Sea region is considered. On the basis of the results of many years research, we established that the earthquake source depths in the Crimea are mainly located in the Earth’s crust and their maximum values do not exceed 60 km. But in some recent articles deep-focus earthquakes in the Crimean region with the source depths up to 300 km were “discovered”. In this connection, it became necessary to study the reason for such a significant discrepancy in depth estimates. On convincing examples we have shown that the sensational “discovery” of the deep earthquake sources in the Crimea is a consequence of the incorrect using the experimental material: gross distortion of the recorded arrival time of body seismic waves; exclusion of data of the nearest stations; unreasonable random sampling of seismic station data; ignoring the materials of the world seismological network, including deep phases. Thus, the conclusions about deep mantle earthquakes in the Crimea are erroneous. The authors re-determined the hypocenter parameters and confirmed that the earthquake depths in the Crimean-Black Sea region do not exceed 60 km. On the basis of these data, an analysis of the features of the spatial distribution of the earthquake depths was carried out. It is shown that the sources are grouped along channels that plunge in the southeast direction from the Crimea mainland towards the Black Sea depression for a group of sources in the Alushta-Yalta and Sevastopol regions. The seismic focal layer of the Kerch-Anapa region plunges in the north-east direction from the Black Sea to the North Caucasus.

 

Keywords: earthquake depth, Wadati graph, seismic waves, deep phases, Crimea, Black Sea.

 

 

About the authors

 

KULCHITSKY Valery Evgenievich — Candidate of Physical and Mathematical Sciences, Senior Researcher, Crimean Expert Council on Seismic Hazard Assessment and Earthquake Prediction. Republic of Crimea, Russia, 295034, Simferopol, ul. Kievskaya 81. Tel.: +7 (365) 244-56-52. E-mail: vekkes@rambler.ru

 

PUSTOVITENKO Bella Gavrilovna — Doctor of Physical and Mathematical Sciences, Chief Researcher, Crimean Expert Council on Seismic Hazard Assessment and Earthquake Prediction. Republic of Crimea, Russia, 295034, Simferopol, ul. Kievskaya 81. Tel.: +7 (365) 254-59-80; Leading Researcher, Institute of Seismology and Geodynamics of the Vernadsky Crimean Federal University. Republic of Crimea, Russia, 295001, Simferopol, ul. Studencheskaya 3. Tel.: +7 (365) 244-56-96. E-mail: bpustovitenko@mail.ru

 

SVIDLOVA Valentina Alekseevna — assistant scientist, Institute of Seismology and Geodynamics of the Vernadsky Crimean Federal University. Republic of Crimea, Russia, 295001, Simferopol, ul. Studencheskaya 3. Tel.: +7 (365) 225-83-34. E-mail: vsvidlova@mail.ru

 

Cite this article as: Kulchitsky V.E., Pustovitenko B.G., Svidlova V.A. On earthquake depths in the Crimean-Black Sea region, Voprosy Inzhenernoi Seismologii (Problems of Engineering Seismology) 2017. Vol. 44, No. 3, pp. 57–82. DOI: 10.21455/VIS2017.3-4 [in Russian].

 

English translation of the article will be published in Seismic Instruments, ISSN: 0747-9239 (Print) 1934-7871 (Online), https://link.springer.com/journal/11990), 2018, Volume 54, Issue 3.