(T1.5-P48) Use of IMS Stations to Provide a New Representation of Kazakhstan

Seismicity

Mikhailova N.N., Aristova I.L., Poleshko N.N., Mukambayev A.S. Institute of Geophysical Researches, Kurchatov, Kazakhstan

Until the end of XX century it was considered that seismically active are only south, south-east and partially east regions of Kazakhstan. This information was used for compilation of the earthquake catalogues and construction of seismic zoning maps of Kazakhstan. After new IMS stations were put into operation on the territory of Kazakhstan and in neighboring countries, the knowledge about spatial distribution of Kazakhstan territory seismicity has been changed significantly. During recent 15 years the following new seismic arrays of the IMS have been installed: Makanchi (PS23), Borovoye (AS57), Kurchatov (AS58), three-component Aktyubinsk station (AS59), seismic arrays Zalesovo (Russia) and Alibek (Turkmenistan), and three-component station Ala-Archa (Kyrgyzstan). AFTAC (USA) has assisted with construction of seismic arrays in Kazakhstan – Karatayu and Akbulak. The stations are located throughout the perimeter of Kazakhstan territory regardless seismic activity level. The monitoring results revealed seismically active zones in Central, Western, Northern and East Kazakhstan. The earthquake catalogue of these regions was compiled. For the earthquakes with intensity up to 7 by MSK-64 scale the focal mechanisms, aftershock activity were investigated in the epicentral zone, data about strong motions were collected. All data are used for creation of a new map of seismic zoning of Kazakhstan that should enter into force since 2016. This work is implemented in cooperation with the Institute of Seismology of Kazakhstan.

IGR network

In recent decades new contemporary digital stations were installed at those regions of Kazakhstan

where the earthquakes were recorded very rarely. Its installation was connected with development of new field of seismology in Kazakhstan – nuclear explosions monitoring. Owing to cooperation with the International organizations – the Comprehensive Test-Ban Treaty Organization, IRIS Consortium, and Air Force Technical Application Center of the USA (AFTAC), a new contemporary network of seismic stations operated by the IGR was established. The stations are located in the West, North and Central Kazakhstan, and near the former Semipalatinsk Test Site in the east of Kazakhstan. The IGR network stations are located regardless seismically active regions of Kazakhstan. The stations are located throughout the perimeter of the Republic of Kazakhstan in very “calm” places in view of seismicity that were especially selected. Most of the stations are seismic arrays. The arrays consist of one-component and broadband three-component seismic recorders. As a rule, all recording equipment of the stations is located in the boreholes (arrays) or in tunnels and shafts on bedrock. The IGR stations are almost completely integrated into the global monitoring networks. This approach to selection of sites, arrays configuration and its aperture, integration of seismic instruments allowed to create very sensitive seismic stations that are currently among the most effective on the number of detected and associated events in the International global networks. Currently, the IGR network includes 5 three-component stations and 7 seismic arrays. Data of this system are used for the tasks of global monitoring for nuclear explosions and earthquakes, and for regional tasks. The data are transmitted to the International Centers for creation of the global seismic bulletins (REB – Reviewed Bulletin of the International Data Center of the Comprehensive Test-Ban Treaty Organization, Vienna, Austria; ISC – International Seismological Centre, Great Britain; EMSC – European Mediterranean Seismological Centre, France; GS RAS – Geophysical Survey of Russia, Obninsk) and to conduct scientific investigations by researchers from different countries (Consortium of Seismological Universities IRIS/DMC), and for implementation of seismic observation tasks of the Republic. The map shows the IGR network stations location. All stations are high-sensitive to regional and teleseismic events. Circles – seismic arrays, triangles – three-component stations. The map of IGR seismic stations location For the seismic bulletin creation the Data Center in addition applies data from foreign regional stations and seismic arrays. The data in real time are received from seismic arrays ZALV (Russia) and ABKT (Turkmenistan), from three-component stations of Kyrgyzstan AAK, TKM2, MNAS and SFK, Turkmenistan TUI, Uzbekistan TAS, Tajikistan DZET, and data from Kazakhstan station MDO, SEME. Tables of arrival times and amplitudes of seismic phases by data of SEME MES RK network stations are used in post-real time with 24-hours delay. About 17 000 events are recorded by the IGR RK network stations per year. 1 – IGR seismic arrays, 2 – three-component The map of earthquakes epicenters stations of the IGR, 3 – foreign arrays, recorded in 2014 by the IGR RK 4 – foreign three-component stations, network stations 5 – seismic phases of SEME stations

Seismic stations which data are used for compilation of the Data Centre seismic bulletins of IGR

New data on Kazakhstan seismicity According to the map of general seismic zoning of Kazakhstan territory included into the Construction Norms and Rules efficient on the territory of Kazakhstan since 2006, the most part of the country’s territory is considered as aseismic. Namely this territory is of high interest for investigation of seismicity using new stations. .Data of recent decades showed that at these territories there were earthquakes with intensity up to 6 – 7 in epicenters by MSK-64 scale. Currently, the understanding of seismicity for different regions of Kazakhstan has changed significantly: a range of source zones at the regions considered earlier as aseismic was revealed.

Seismicity of Central Kazakhstan The territory of Central Kazakhstan is traditionally considered as aseismic. However, after the IGR RK stations were put into operation several earthquakes were recorded at Central Kazakhstan. The largest was Shalginskoye earthquake that occurred 198 km south-east of Zhezkazgan in 2001; the earthquake intensity at the epicenter was 6 by MSK-64 scale, magnitude 5.2. 1-Shalginskoye earthquake 2- Karaganda earthquake - IMS stations The map of earthquakes with magnitude more than 3 in Central Kazakhstan. Shalginskoye earthquake. The understanding of seismic hazard of this region has changed radically after the earthquake of August 22, 2001 in 22 hours 58 minutes local time 198 km south-east of Zhezkazgan town near Shalginskiy settlement. The earthquakes with intensity 6 in the epicenter by MSK-64 scale. The parameters of the main shock by data of different Processing Centers Record of Shalginskoye earthquake of 22.08.2001 Focal mechanism of Shalginskoye earthquake of 22.08.2001 Karagandinskoye earthquake. One June 21, 2014 all seismic stations of the IGR network have recorded another quite large earthquake in Central Kazakhstan. In Karaganda (33 km from the epicenter) its intensity was 4

The main parameters of Karagandinskoye earthquake

Earthquake record of 21.06.2014 Focal mechanism of 21 June 2014 earthquake near Karaganda

Seismicity of Western Kazakhstan Large prospect for this region investigation appeared after installing of Aktyubinsk (AS059) station and Akbulak seismic array. A range of earthquakes was recorded, the largest event – Shalkarskoye earthquake with magnitude 5.4, intensity 7-8 by MSK-64 scale. Induced earthquakes of Western Kazakhstan are of high interest, in particular those occurring at Tengiz oil deposit distinguished by intensive raw hydrocarbon production (oil). 1 - Shalkar earthquake 2 - Tengiz induced earthquakes - IMS stations The map of earthquakes in the west of Kazakhstan with magnitude more than 3 and Tengiz induced earthquakes.

Shalkar earthquake occurred on April 26, 2008 in 13:14:52 Greenwich time in the west of Kazakhstan. Its epicenter was located in automated mode at the Data Centre, IGR by data of the IGR RK stations. The earthquake parameters are shown in the Table. The main parameters of Shalkar earthquake of 26.04.2008 by data from different global seismic networks

Focal mechanism of 26.04.2008 earthquake

The waveforms of the infrasound Records of Shalkar earthquake signal from Shalkar earthquake of April 26, 2008 by NNC RK seismic stations According to seismic, geologic and tectonic characteristics of the investigated area it can be stated that Shalkar earthquake of April 26, 2008 is natural tectonic event connected with karst process and active salt diapirism. Influence of such natural tectonic earthquakes on appearance of induced seismicity at hydrocarbon production deposits located at the same area and vice versa is quite possible. On July 18 the same year there was another smaller earthquake, Mb=4.1 that was also recorded by the NNC RK stations and processed together with other stations of the world. Tengiz induced earthquakes. Akbulak seismic array of the IGR network records seismic events near Tengiz oil deposit. The largest earthquake with magnitude 3.6 occurred on February 21, 2011. The main parameters of the earthquake occurred on the territory of Tengiz oil deposit Record of Tengiz earthquake of May 23, 2014

Seismicity of Eastern Kazakhstan and STS

After the IMS stations Kurchatov and Makanchi were put into operation the number of earthquakes recorded from the east of Kazakhstan and STS territory increased significantly. The map of earthquake epicenters from historical times to 2013 with magnitude 3 and more. The largest earthquake recorded by the IGR network at this territory had 20.01.2015 09:30:57 magnitude 5.3. According to historical data the largest event happened in 28.09.1925 and had magnitude 5.8. The records of the IGR RK stations for the earthquake 20.01.2015 .

Conclusion

The IMS stations installed in aseismic territory of Kazakhstan recorded a set of seismic events: natural earthquakes, induced earthquakes, and industrial blasts. All data received for recent 15 years – period of the IMS stations operation in support of the CTBTO – are considered while creating of a new map of general seismic zoning of Kazakhstan territory. The map should come into effect in 2016. New seismic generating zones were revealed, its Mmax were estimated. Introduction of this map into seismic engineering practice is a result of successful operation of the IMS stations in ensuring of seismic safety and decrease of possible damage after future large earthquakes.

Appearance of the earthquakes at places unexpected for seismologists confirms that seismic events monitoring should be conducted for the whole territory of Kazakhstan regardless a priori representation about seismicity or its lack in this or that region. Solving of this task to some degree became possible after new IGR network stations were installed. To confine a territory for data acquisition the current map of general seismic zoning of the Republic of Kazakhstan was applied. In the Figure the selected territory is confined by the red line.

Blue triangles – IGR stations, red – SEME stations The border of the selected low-active territory of Kazakhstan

For the selected territory the database for 350 earthquakes from historical times to 2013 was created.

1- MLHnew<1; 2- 1 ≤ MLHnew < 2; 3- 2 ≤ MLHnew < 3; 4- 3 ≤ MLHnew < 4; 5- 4 ≤ MLHnew < 5; 6- 5 ≤ MLHnew; 7- cities; 8 - Astana.

The map of earthquake epicenters from historical times to 2013. The analysis of data from permanent high-sensitive network of IGR RK seismic stations located in seismic and “aseismic” regions of Kazakhstan has shown that the total number of processed and localized seismic events in these zones is several thousand per year! It was clear that most of them are not natural events, but connected with industrial activity at mines. Often, the epicenters of earthquakes and explosions are close to each other. For compilation of reliable earthquake catalogues and correct assessment of seismic hazard the accurate identification of the recorded events nature is necessary. Since 2004 the KNDC is engaged in compiling of explosions catalogues. Among otal number of the processed seismic events the following were the blasts: in year 2004 – 1464, 2005 – 1770, 2006 – 3144, 2007 – 4604, 2008 – 4844, 2009 – 5136, 2010 – 5153, 2011 – 4702, 2012 – 5713, 2013 – 6523.

The map of industrial blasts epicenters on the territory of Kazakhstan and bordering countries. Thus, it should be noted that streams of seismic energy in low-active regions are formed from different sources: earthquakes of different nature and large amount of explosions. The plot shows all earthquakes in low-active territory for four years since 2010 to 2013 with its magnitude values. Total number of earthquakes is 216, mpv magnitude ranges from 1.1 to 4.0. One event had magnitude more than 5. .Data of recent decades showed that at these territories there were earthquakes with intensity up to 6 – 7 in epicenters by MSK-64 scale. Currently, the understanding of seismicity for different regions of Kazakhstan has changed significantly: a range of source zones at the regions considered earlier as aseismic was revealed. Earthquakes distribution by Distribution of explosions magnitude and time in low-active by magnitude and time at low-seismicity regions of Kazakhstan regions of Kazakhstan. Total released energy of explosions for this period of time is 2.6·1011 J. Total released energy of earthquakes at the same territory is 1.04·1012 J.

0,0

2,0

4,0

6,0

2010 2011 2012 2013 2014

MPVA

# item Date Origin time, T0 Latitude,

j°, N Longitude,

l°, E Magnitude, Мs

Energy class, K

Bulletin

1 22.08.2001 15 58 01.82 47.16 70.20 5.0 - NEIC

2 22.08.2001 15 57 59.24 47.112 69.950 4.7 - REB

3 22.08.2001 15 57 58.8 47.20 70.14 5.0 - GS RAS

4 22.08.2001 15 57 57.70 47.20 70.20 5.0 (Mpv=5.4) 13.2 KNDC

# item Date Origin time,

T0 Latitude,

j°, N Longitude

, l°, E

Magnitude, Energy class, K

Bulletin Мs

1 21.06.2014 6:30:04.3 49.57 72.90 4.8 EMSC

2 21.06.2014 6:30:02.8 49,53 72,98 5 12 GS RAS

3 21.06.2014 6:30:03.4 49,56 72,97 5.2 11,7 KNDC

# item Date Origin time, T0 Latitude, j°,

N Longitude,

l°, E

Magnitude, Bulletin

Мb

1 26.04.2008 13:14:51.40 50.785° 51.623° 4.6 REB(IDC)

2 26.04.2008 13:14:54.80 50.334° 52.497° 4.3 KNDC

3 26.04.2008 13:14:51.90 50. 59° 51.86° 5.0 EMSC

4 26.04.2008 13:14:50.10 50.57° 51.79° 5.3 GSRAS

5 26.04.2008 13:14:52.00 50.46° 51.85° 5.0 NEIC

# item Date Origin time, T0 Latitude, j°,

N Longitude,

l°, E

Magnitude,

Мb

1 21.02.2011 9:03:25 46.09 53.47 3,6

2 23.05.2014 21:03:52 46.0885 53.445 3,6

3 05.02.2015 22:38:00 46.0208 53.4687 3

4 06.02.2015 5:51:38 46.0565 53.3395 3

5 14.04.2015 16:44:09 46.1117 53.4427 2,48