METADATA IN ENGLISH

 

About the journal

SEISMICHESKIE PRIBORY, ISSN: 0131-6230, eISSN: 2312-6965, DOI: 10.21455/si, http://elibrary.ru/title_about.asp?id=25597)

English Translation: Seismic Instruments, ISSN: 0747-9239 (Print) 1934-7871 (Online),

https://link.springer.com/journal/11990

 

Method of constructing geoelectric section model taking into account its seasonal variations based on data
of long-term monitoring by VES aimed at searching
for earthquake precursors

 

© 2017 A.V. Desherevskii1, I.N. Modin2, A.Ya. Sidorin1

 

1 Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia

2 Lomonosov Moscow State University, Moscow, Russia

Corresponding author: A.Ya. Sidorin, e-mail: al_sidorin@hotmail.com

 

Highlights

·         The data of precision VES with spacing from 2 to 650 m are analyzed

·         Observations were carried out at the Garm polygon every day for 12 years

·         New approach to interpretation of more than 3000 repeated VES at one site is proposed

·         Geoelectric section model taking into account its seasonal variations is constructed

·         Residuals and region of model equivalence are reduced by an order of magnitude

 

Abstract. The data of high-precision measurements of apparent resistivity at a stationary multi-electrode vertical electric sounding (VES) system including 12 current  and 4 potential lines with spacing from 2 to 650 m are analyzed. Observations were carried out at the Garm polygon daily for 12 years as part of the earthquake prediction experiment. The use of special technical methods during measurements made it possible to provide an instrumental error of about 0.01 %. The actual error of each individual measurement of the apparent resistivity (taking into account all possible noise) was 0.1–0.2 %. The presence of more than 3000 VEZ curves measured in different seasons of the year allows us to propose a new approach to the construction of a geoelectric section model. To solve the inverse problem of the VES, a set of 36 ten-days averaged VES curves was analyzed, each of which was obtained by averaging approximately 100 individual VES curves obtained in the same 10-day period of the annual (seasonal) cycle in different years. A comparative analysis of these curves made it possible to calculate and include corrections for stationary geological noise in the model. As a result, it was possible to substantially reduce (by an order of magnitude) the residuals of the curves fitting and dramatically narrow the equivalence domain. Based on the results of the analysis, a model of a 4-layer horizontally layered geoelectric section of the Khazor-Chashminskaya depression is constructed, adequately describing not only the averaged section, but also its seasonal variations throughout the year. The stability of estimation of model parameters is studied. To further reduce the equivalence domain, it is suggested that the layer thicknesses be fixed. The model constructed can be used not only to study the aforementioned characteristics of the section, but also to monitor the time variations of the resistivity in its individual layers. This will significantly improve the resolving power of systems for detecting time variations in the geoelectric section, including when searching for earthquake precursors.

 

Keywords: geoelectric monitoring, VES, interpretation, geoelectrical section, seasonal variations, Garm polygon, earthquake precursors.

 

About the authors

 

DESHEREVSKII Alexey Vladimirovich – Candidate of Physical and Mathematical Sciences, Leading Researcher. Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences. 123242, Moscow, ul. Bolshaya Gruzinskaya, 10, str. 1. Phone: +7(499) 254-90-35. E-mail: adeshere@ifz.ru

 

MODIN Igor Nikolaevich – Doctor of Technical Sciences, Professor, Moscow State University. Lomonosov Moscow State University. 119991, Moscow, Leninskie Gory, 1. E-mail: imodin@yandex.ru

 

SIDORIN Alexander Yakovlevich – Candidate of Physical and Mathematical Sciences, Head of Laboratory. Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences.  123242, Moscow, ul. Bolshaya Gruzinskaya, 10, building 1. Phone: +7(499) 254-42-68. E-mail: sidorin@ifz.ru

 

Cite this article as: Desherevskii A.V., Modin I.N., Sidorin A.Ya. Method of constructing geoelectric section model taking into account its seasonal variations based on data of long-term monitoring by VES aimed at searching for earthquake precursors, Seismicheskie Pribory, 2017, Vol. 53, no 4, pp. 61-80. DOI: 10.21455/si2017.4-5 (in Russ.).

 

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 4.