Information message about the strong earthquake in Southern Xinjiang, China on March 20, 2008.

     The strong earthquake with М=7.4 has occured on March 20, 2008 at 22:32 GMT (March 21 at 1:32 Moscow time)in Southern Xinjiang, China.
     Parameters of the earthquake have been determined in the Alert Service (AS) of Information Processing Center (IPC) of Geophysical Survey of RAS in Obninsk with station data obtained from digital and analog seismic stations of Russia, countries of CIS and from abroad. Alert message on this earthquake has been delivered in 27 min after registration to the Ministry of Emergency of the Russian Federation (EMERCOM).
     Preliminary processing has been done with data from 39 stations, accurate processing - with data 53 stations.
     Fig. 1 presents fragments of records obtained from digital stations Ala Archa (∆ 9º), Kurchatov (∆ 15.4º), Borovoe (∆ 19.3º), Talaya (∆ 22.7º), Arti (∆ 26.1º). Fig. 2 presents fragments of records obtained from digital stations Garni (∆ 29.2º), Kislovodsk (30.7º), Obninsk (∆ 36.4º), Yakutsk (∆ 40.1º), Tiksi (∆ 43.7º).

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 22-32-57.5 35.47 81.41  20  53  7.4/215.9/309.546 IPC GS RAS (Accurate)
2 22-32-59.6 35.51 81.38  33  39  7.4/195.9/228.5-946 IPC GS RAS (Preliminary)
3 22-33-00.3 35.46 81.4  40  342  7.1Mw   48 CSEM
4 22-32-56.8 35.44 81.37  1.7  116  7.2Mw    NEIC (Preliminary)
5 22-33-00.0 35.45 81.39  22.9  145  7.2Mw 6.2/131 25 NEIC (Accurate)
  • 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
    • Epicenter
         Fig.3 downloaded from NEIC depicts epicenter of this earthquake, which was located in Southern Xinjiang in the border area between China and Idia at the depth of 20 km., at 225 km to the south-east from Hotan (China) and at 375 km to the east-north-east from Lekh (Kashmir).

    Figure 3
    Aftershock
         This earthquake was accompanied with aftershocks. In 14 hours after the main shock GS RAS has registered 14 aftershocks.
    N Date   &   Time (GMT)
    yy-mm-dd hh:mm:sec    		 Lat
    degr.    		 Lon
    degr.    		 Depth
    km    		 N
    station    		 Ms/ N mb/ N Io
    calc.    		 Region
    200808782008-03-20 22:50:35.035.1680.713318-5.5/ 124.5-5 Kashmir-Xizang border region
    200808792008-03-20 23:12:02.035.5681.33330-5.6/ 175 Southern Xinjiang, China
    200808802008-03-20 23:50:06.035.2481.432024-5.2/ 154.5-5 Southern Xinjiang, China
    200808812008-03-20 23:55:01.035.4981.342019-4.8/ 113.5-4 Southern Xinjiang, China
    200808832008-03-21 00:10:36.035.5381.462018-5.0/ 124-4.5 Southern Xinjiang, China
    200808842008-03-21 00:26:16.035.9581.222022-5.3/ 145-5.5 Southern Xinjiang, China
    200808852008-03-21 00:48:49.035.280.973317-4.9/ 113-3.5 Kashmir-Xizang border region
    200808862008-03-21 01:08:53.035.8981.622015-4.8/ 83.5-4 Southern Xinjiang, China
    200808872008-03-21 01:46:56.035.8681.69208-4.8/ 53.5-4 Southern Xinjiang, China
    200808892008-03-21 04:03:25.035.6681.461024-5.0/ 145-5.5 Southern Xinjiang, China
    200808902008-03-21 04:52:32.035.6681.541017-4.8/ 84.5-5 Southern Xinjiang, China
    200808922008-03-21 06:16:02.035.6681.521021-4.9/ 125-5.5 Southern Xinjiang, China
    200808962008-03-21 11:09:28.035.6281.321014-4.4/ 24 Southern Xinjiang, China
    200808972008-03-21 12:02:53.035.4681.511023-5.0/ 135-5.5 Southern Xinjiang, China
    Macroseismic manifestations
         More thatn 70 thousand people have been influenced after the series of powerful shocks, which happened on friday in Xinjiang-Uigur autonomous region of China. This information was published by the local mass media. In accordance with some sources the undeground shocks have totally distroyed 500 buildings in some parts at the west of this autonomous region, more than 20 thousand other buildings have been hit, including schools, hospitals and so on. Estimation of destructions from this natural disaster is continued now. No reports have been made about the killed people (in accordance with ITAR-TASS).
    Focal mechanism and seismic moment of the earthquake
         Focal mechanism solutions of the earthquake 20.03.2008 have been obtained with TMC method in National Information Center of NEIC, in USGS and in Harvard Center, USA (Global CMT Catalog), they are presented in table 2 and shown on fig. 4, 5. All solutions are identical. This earthquake has happened under prevailing action of expansion forces oriented to the north-west direction. Nodal plane NP1 propagated almost along meridian, the other plane NP2 - from the north-east to the south-west. The type of motion along both planes – fault with shift components (right side along NP1 and left side along NP2). The values of seismic moment Мо obtained in GS RAS from Р-wave spectra at two stations: "Obninsk" - delta 36.4 degrees, "Kislovodsk" - delta 30.7 degrees, makes Мо=2.8* 10** 19 n*m. The values of moment magnitude Mw calculated from Kanamori formula is equal to Mw = 6.9; The values of seismic moment Мо obtained from USGS data makes 8.3* 10** 19 n*m, the value of moment magnitude makes Mw = 7.2 and from HRVD data Мо=5.52* 10** 19 n*m, Mw = 7.1.
    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
    2129360159 193135329-131219 69-68NEIC
    128073188 171135447-113206 48-67HARVARD
  • NEIC - National Earthquakes Information Center of US Geological Service
  • HARVARD - Harvard Geophysical Center (USA)

    • Figure 4
    Figure 5


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