Information message about the earthquake in Tajikistan on January 9, 2002

     The sensitive earthquake has happened in Tajikistan on January 9, 2002. It occured at 09 hours 45 minutes Moscow time (06:45 GMT) and had magnitude 5.0 and intensity up to 6-7 MSK.
     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 1 ÷ 24 min after registration to the Ministry of Emergency of the Russian Federation (EMERCOM).
     Preliminary processing has been done with data from 16 stations, accurate processing - with data 25 stations.
     Figures 1-2 present fragments of waveforms, which have been obtained by IPC from digital stations in a near to real time mode. Information about macroseismic manifistations of this event in Tajikistan has been obtained by IPC GS RAS from seismic station "Dushanbe" and from ITAR TASS.

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 06-45-55.30 38 69  20  25  5.00/105.00/76-7 IPC GS RAS (improved)
2 06-46-05.3 39 69  80  16  5.0/74.9/53.5-4 IPC GS RAS (preliminary)
3 06-45-48.9 37 70  10    5.5    CSEM
4 06-45-57.1 38 69  33    5.3/855.2/18  NEIC
  • 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
         This earthquake has happened in 80 km to the East from capital Dushanbe.
    Macroseismic manifestations
         Maximum macroseismic activity reached 6-7 MSK in the hypocenter's nearest town Ragun. According to ITAR TASS data 3 men have been lost here on January 10 (all of them are kids), 54 people were injured and 580 people have lost their homes. On January 11 in his interview to ITAR TASS the first deputy chief of Tajikistan Ministry of Extraordinary Situations has said that the damage to Ragun town and nearest places from this event has reached 600K USD. 31 dwelling houses, 4 high schools, 4 medical points and 25 kilometers of highway have been fully destroyed, including dozens of kilometers of electric power supply lines. This earthquake has been felt in Dushanbe with intensity 3-4 MSK.
    Historical records
         Hypocenter of this earthquake has been located in Gissarsk mountain ridge, between origin zones of the strongest (intensity 9-10 MSK) and catastrophic earthquakes of Tajikistan, which occured long enough before and had magnitudes more than 7.0: these are Karatagsk event 1907 (Ðœ=7.3 and Ðœ=7.4) and Haitsk event 1949 Ðœ=7.4. Besides then this area is characterized by those destructive (8-9 MSK intensity) earthquakes with less magnitudes, as Garm earthquake 1941 M=6.4 and Faizabad earthquake 1943 M=6.0. During the instrumental period (device measurements) since 1955 and up to 2001 in accordance with "Seismological operative bulletin of CEME GS RAS" nine earthquakes have been registered in the area with radius of ±0,5o from hypocenter of described here event 2002. All of these events had small magnitudes 4.7 - 5.3, but surface shakes from them reached 6 – 7 MSK. During the previous 30 years this zone has been characterized by smaller seismic activity, only one earthquake with magnitude close to 5 has been registered here – it happened on November 8, 1992 and had magnitude 4.7. Location of the earthquake on January 9, 2002 with regard to the strongest earthquakes of Central Asia having magnitude Ðœ>=6.5 and in accordance with "Specialized catalogue" (editors Kondorskaya N.V., Ulomov V.I.) is shown on fig.3.

    Figure 3
    Focal mechanism and seismic moment of the earthquake
         Focal mechanism of the earthquake 01.09.2002 has been calculated in CEME GS RAS from the first signes of longitudinal wave arrivals at 16 stations, which are located in the interval of hypocentral distances 0.7-87 degrees. Mainly these stations are located to the North, North-West and North-East from this event's hypocenter and provide sufficient azimuth surrounding hypocenter, thus the obtained solution may be considered as only preliminary estimation, which requires additional improvement. Parameters of focal mechanism are presented in table 2 and shown on fig. 4. Focal mechanism represents uplift along the both nodal planes, one of them (with more steep falling angle) has close to meridional spread direction, the other one plane (gently sloping) - has almost latitudinal spread direction. The motion was initiated by the prevailing action of compression strengths oriented to the North-East.
    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
    582981147 291431054243340 62124IPC GS RAS
  • IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences

    • Figure 4


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