Major Results of 2017

Result №1

The new breadboard model of electrical survey equipment with noise-like signals (ЭРК ШПС) notable for advanced technical features and parameters was developed and constructed (fig.1). Laboratory measurements of signal-noise ratio As/An for two breadboard ЭРК ШПС models showed that the signal-noise ratio measured for the new ЭРК ШПС model increased by 22 dB (12.6 times) in comparison with the model constructed earlier.

The ЭРК ШПС measuring complex is planned to be used in electromagnetic monitoring of stressed and deformed state of the Earth’s crust at measuring sites of Bishkek geodynamic proving ground.

Figure 1 – External view of the measuring channel of the new ЭРК ШПС breadboard model:

1 – induction signal transmitter; 2 – power supply of the induction signal transmitter; 3 – calibration signal shaper; 4 - signal filtering unit; 5 – unit of signal control and record ; 6 – power supply of the unit of signal control and record

Authors:

Pavel Ilyichev, Vladimir Bobrovsky, Maksim Lisimov

Publications:

1.             Ильичев П.В. Оптимизация технических параметров и характеристик геоэлектроразведочного измерительного комплекса с шумоподобными сигналами // Проблемы геодинамики и геоэкологии внутриконтинентальных орогенов: Тезисы докладов VII Международного симпозиума, г. Бишкек, 19-24 июня 2017 г. – Бишкек: НС РАН, 2017. – с. 409-412.

2.             Лашин О.А. Разработка блока управления и регистрации сигналов для геоэлектроразведочного измерительного комплекса с шумоподобными сигналами // Современные техника и технологии в научных исследованиях: Сборник материалов IX Международной конференции молодых ученых и студентов.– Бишкек: НС РАН, 2017. с. 84-92.

Result №2

Space-time relationship between local seismicity and variations of deformation state of the Earth’s crust was registered at the territory of Bishkek Geodynamic Proving Ground (Northern Tien Shan).

Results of linear-angular and GPS observations in comparison with seismicity and source mechanisms made it possible to estimate geodynamic environment during local earthquake of 10 energy class. Several days before the earthquake, GPS data showed the lowering of the earth surface with amplitude up to 20 mm in this area. 5 days before and 2 days after the event, optical range measurements showed the increasing of lengths of lines crossing the Shamsi Fault on average by 8 mm within ~2 km from the earthquake source. Such increasing of fault width corresponds to variations of tectonic stresses ~7MPa near the fault.

Figure. Layout of researched area showing the location of grounds (sites and their numbers) of linear-angular observations POLIGON, KENTOR and ALMALY (1), GPS sites IATA, IAT3, POL2, CHUM (2), transient electromagnetics stations (3) and seismic focus (4)  - focal mechanism. Lines – active faults.

Authors:

Sergey Kuzikov, Vitaly Bragin, Nelya Sycheva

Publications:

Соболев Г.А., Кузиков С.И., Брагин В.Д., Сычева Н.А. Изменение деформаций на территории геодинамического полигона на Тянь-Шане и местное землетрясение 12.02.2013 г. // Геофизические исследования. 2017. Т.18. №3. С.45-59.

1. We have determined the structure of modern movements of the Earth’s crust at the territory of Pamir and its closest northwestern surroundings according to GPS observations data.

According to GPS observations data, for the first time it was shown that the massif of Pamir is not a monolithic block and that between its outer GPS points there are differences in horizontal velocity vectors by 3-10 mm/year.  The eastern boundary of Pamir Mountains and Tarim Depression is feebly marked kinematically with a slight lagging of Tarim from Pamir up to 2-4 mm/year, with their common movement to the north and moving of Tarim’s northern part away from Pamir to the east. Maximal crustal shortenings in this region are situated in the arc-shaped zone of the northwestern framings of Pamir 35-60 km wide, and the Pamir massif moves north-westward (~ 320°) with 11-14 mm/year velocity relative to the territory of Tajik Depression and Western Tien Shan.

(The work was headed by Vladimir A. Zeigarnik, Doctor of Engineering, RS RAS, tel. 996-312-613140)

 2. We have received a stable response of variations of apparent resistance to the changes of stressed-deformed state of medium in the interval of effective depths from 1.5 km to 5 km triggered by a large industrial explosion. To explain the recorded variations we suggested a hypothesis about redistribution of fluid in the system of related cracks during deformation of rock massif.

According to the data of seismological observations, the Kambarata industrial explosion has triggered two small earthquakes at a distance ~15 km which changed the stressed-deformed state of medium and caused changes in electrical properties of medium. The results of processing of magnetotelluric monitoring data indicated significant variations of apparent resistance of the opposite sign on the orthogonal azimuths of observations. Such behavior of variations proves the hypothesis about redistribution of fluid in the system of related cracks during deformation of rock massif.  

(The work was headed by Anatoly K. Rybin, Candidate of Science in Physics and Mathematics, RS RAS, tel. 996-312 - 613140)

3.  We have revealed the effect of microseisms generation during electric sounding sessions using a powerful electropulse system ERGU 600-2.

We have ascertained that during the sessions of electric sounding of the Earth’s crust by powerful current pulses (600 A) on a large area around the electric dipole (30×30 km), there appears a series of microseisms which causes a discharge of the stressed state of the Earth’s crust.  Generation of microseisms occurs both during the sounding session and after the session. 

Generation of microseisms was caused by the forced seismic vibrations in the medium which occur during electric sounding.  The optimal matched filtering of seismic signal made it possible to distinguish the response in seismic field from the pulse current sequence generated by ERGU 600-2 in electric dipole. 

(The work was headed by Vitaly D. Bragin, Candidate of Science in Physics and Mathematics, RS RAS, tel. 996-312-613140)