Information message about the earthquake in Western Turkmenistan on December 6, 2000

     On December 6, 2000 the strong earthquake has happened in Western Turkmenistan wih magnitude 7.4. This earthquake has been felt in many towns of Turkmenistan, Azerbaijan, Middle Asia and on the territory of Russia ? in Dagestan, towns of Stavropol Region, in Saratov and Astrahan cities. Echo of this event has bben felt in Moscow and St.Petersburg.
     Parameters of the earthquake have been determined by the Alert Survey (AS) of Information Processing Center (IPC) of Geophysical Service RAS in Obninsk with use of station data obtained from digital and analog seismic stations of Russia, countries of CIS and from abroad. Alert message about this earthquake has been delivered in 24 operative duty in Russian Civil Defence and Liquidation of Natural Disasters Ministry.
     Improved calculation has been done on the basis P-wave arrivals from 25 stations. Additional data has been received from other stations of Russia as well as from Republican seismology service (RSS) of Azerbaijan Academy of Sciences and Institute of seismology of Turkmenistan cabinet of ministers.
     Figures 1-2 present records from digital stations, which were sent to IPC in a close to real time mode.

Figure 1
 

Figure 2
 
     IPC GS RAS also has obtained information with parameters of this event from some seismological centers, these data are given in table 1:
Table 1
NN Time in origin h-min-s (GMT) Lat degr. Lon degr. Depth km N s/st Ms/ N mb/ N I0 calc GAP Center
1 17-11-05.80 39 54  33  15  7.40/66.40/38.5-9 IPC GS RAS (preliminary)
2 17-11-06.0 39 54  33  25  7.4/66.4/38.5-9 IPC GS RAS (improved)
3 17-11-05.3 39 54  10  156  7.0-7.4 6.5-7.0   CSEM
4 17-11-07.9 39 54  33  95  /86.7/61  NEIC
5 17-11-06.5 39 54  19  23   6.2/17  IDC
  • IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences
  • CSEM - European - Mediterranean seismological center
  • NEIC - National Earthquakes Information Center of US Geological Service
  • IDC - International Data Senter, Austriya, Viena
    • Aftershock
         The earthquake on December 6 has been accompanied with aftershocks. Parameters for the strongest of them having magnitudes more than 3.5 are given for December 7 at 14-00 Moscow time on the pages of "Alert Survey" server http://www-ceme.gsras.ru with numbers 1526, 1528, 1529.
    Macroseismic manifestations
         This earthquake has been felt on a vast territory. From messages of seismologists on seismic stations "Ashhabad" and "Tashkent" it was determined, that the most strength of this event has been felt in towns of Turkmenistan. In Nebit-Dage the intensity reached VII MSK in MSK 64. Macroseismic data for Krasnovodsk town from these stations are inaccurate and make from IV to VI MSK. According to Turkmenistan seismologists his earthquake has been felt in Kizil-Arvat - V MSK, in Ashgabat - IV MSK. In Nebit-Dage electric power supply has been interrupted after the underground shock. Equipment, furniture, TV sets and even iron ovens were falling down in the post offices and communication has been cut. Effect in Krasnovodsk was weaker. Uzbekistan seismologists reported that this earthquake was felt in Nukus with IV - V MSK, in Buhara, Samarkand, Karshi, Harezm – with III MSK, Tashkent – II- III MSK. Besides that Alert Survey has received the following macroseismic data: this earthquake was felt in Azerbaijan (Baku city - IV MSK) and on the territory of Russia – in Saratov city – up to V MSK, in Dagestan Region (Mahachkala, Izberbash) – III –IV MSK, in Stavropol Region - Piatigorsk town and Gofitskoe place – III MSK. Echo of this earthquake reached Moscow and St.Petersburg cities – chandeliers were swinging and plates jingling on the upper floors of buildings (nearly II MSK).
    Historical records
         Analysis of publications on seismic activity of Western Turkmenistan shows, that this region in the last century featured the high level of seismic activity. From data of "Specialized Catalogue" (red. Kondorskaya N.V., Ulomov V.I.) the strongest and destructive Krasnovodsk earthquake has happened here in 1895 (1 - on fig. 3) with coordinates 39.6N 53.7E, magnitude Ms=7.9 and intensity in hypocenter IX MSK in MSK64. It was felt on vast territory – from Northern Iran to Middle Volga and South Urals.("New catalogue of strongest earthquakes on USSR territory"). In 1946 the strong earthquake originated in the region of Kazandjic town (Western Kopetdag) (2 - on fig. 3) with coordinates 39.83N 54.62E, magnitude Ms=7.0 and intensity in hypocenter VIII-IX MSK. Some other significant underground shocks have bben noticed here: on March 14, 1983 in Kumdag settlement (3 - on fig. 3) with coordinates 39.3N, 54.6 E and magnitude Ms=5.7 and on February 22, 1984 in Burun settlement (4 - on fig. 3) with coordinates 39.34 54.07 and magnitude Ms=5.6. Both these earthquakes had intensity in hypocenter VIII MSK (fig. 3). It is possible to assume, that Baku earthquake – on November 25 with magnitude Ms=6.2 and West Turkmenistan earthquake on December 6 with magnitude Ms=7.4 are called by the same reasons – active tectonic motions on the border of two biggest structures of the earth crust – Turansk plate and Kopedag-Caucasian folded plate motion area. Zone of the first earthquake gravitates towards Apsheron-Chelekensk deep crust break, while the zone of the other – to its Eastern extension – Chelekensk – Kumdagsk break. Fig. 3. Locations of hypocenters for the earthquake on December 6, 2000 and for the strongest known events in this zone (1-1895, 2- 1946, 3-1983, 4-1984). Here the location of Baku earthquake hypocenter on November 25, 2000 is shown.

    Figure 3
    Focal mechanism and seismic moment of the earthquake
         Tabe 2 and figure 4 present solutions of focal mechanism for the earthquake on December 6 at 17-11, which were obtained in Harvard, USA from CMT method – (1) and in IPC GS RAS (2) with use of P- first motions. Data about the first P-wave motions (24 motions "Up" and 10 motions "Down") have been obtained at 40 stations located in hypocentral intervals 3.76-99.3 degrees. Focal mechanism solutions obtained from different methods have common features. In both solutions one of nodal planes has spread direction from the North-West to the South-East, that corresponds with the spread direction of deep Cheleken – Kundaginsk earth break. Thrust component dominates, motion in the origin place is going under the action of compressing stresses, axes of compression in both solutions are almost horizontal and oriented to meridian direction. Seismic moment Мо of the earthquake was determined from Р-wave spectra registered by IRIS digital equipment at TLY station (Talaya, Irkutsk Region), which is remoted from hypocenter at the distance of 35.6 degrees. The value of Мо made 3.7 Е 19 n* m. The value of Мw is equal to 7.0. It was determined from CMT method and according to Harvard data made Mw=7.0
    Table 2
    Axes of main strengths Nodal planes Center
    T P N NP1 NP2
    Pl Azm Pl Azm Pl Azm Stk Dp Slip Stk Dp Slip
    529536296 101992534736137 65131IPC GS RAS
    6732220110 112043183812497 5966HARVARD
  • IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences
  • HARVARD - Harvard Geophysical Center (USA)

    • Figure 4
    Figure 5


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