Information message about the strong earthquake in the region of Andaman Islands, India, August 10, 2009.

     The strong earthquake with М=7.6 has occured on August 10, 2009 at 19:55 GMT (23:55 Moscow time) in the region of Andaman Islands, India.
     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 22 min after registration to the Ministry of Emergency of the Russian Federation (EMERCOM).
     Preliminary processing has been done with data from 43 stations, accurate processing - with data 47 stations.
     Fig. 1 presents fragments of records obtained from digital stations Ala Archa (∆ 32.6º), Taejon (∆ 37.9º), Vladivostok (∆ 44.2º), Arti (∆ 49.7º), Kislovodsk (∆ 52º). Fig. 2 presents fragments of records obtained from digital stations Tennant Creek (∆ 53º), Yakutsk (∆ 54.5º), Obninsk (∆ 59.5º), Petropavlovsk (∆ 64.3º), Lovozero (∆ 65.3º).

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 19-55-38.5 14.11 92.92  33  47  7.6/236.9/199 60 IPC GS RAS (Accurate)
2 19-55-37.6 13.98 92.98  33  43  7.7/236.9/179-9.5 96 IPC GS RAS (Preliminary)
3 19:55:38.9 14.06 92.9  25  192  7.6 Mw   62  CSEM
4 19:55:39.2 14.01 92.92  33.1  64  7.6Mw 7/51 72 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
         Fig. 3 presents with yellow star epicanter of this earthquake, which was located in the region of Adamans Islands, India, at the depth of 33 km., in 470 km. S-W off Yagun, Myanmar, in 820 km W-N-W from Bangkok, Thailand and in 1380 km E-N-E off Madras, India.

    Figure 3
    Aftershock
         GS RAS registered 7 aftershocks with magnitudes from 4.8 to 5.4 within the day after the main shock.
    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
    200925602009-08-10 21:19:39.014.4292.893314-5.1/ 113.5-4 Andaman Islands, India region
    200925622009-08-11 00:20:08.014.0293.23314-4.8/ 73-3.5 Andaman Islands, India region
    200925632009-08-11 06:10:01.014.0392.943312-5.0/ 63.5-4 Andaman Islands, India region
    200925642009-08-11 07:14:34.014.2893.083314-5.0/ 93.5-4 Andaman Islands, India region
    200925652009-08-11 07:54:35.014.3293.033321-5.4/ 104.5 Andaman Islands, India region
    200925672009-08-11 08:32:09.014.1493.073313-5.0/ 103.5-4 Andaman Islands, India region
    200925702009-08-11 15:19:06.014.13933314-4.8/ 103-3.5 Andaman Islands, India region
    Macroseismic manifestations
          In accordance with NEIC, USA this earthquake was felt in India, Sri-Lanka, Indonesia, Myanmar, Thailand, Bangladesh, China, Nepal, Vietnam and Maldives with intensities up to 6 MSK. Fig. 4 shared from NEIC, USA , presents the map with intensities obtained from phone calls made by 503 respondents in 78 places.

    Figure 4
    Historical records
         This earthquake has occurred on August 10, 2009 in Indian Ocean to the north from catastrophic earthquakes December 26, 2004 with М=8.8 and March 28, 2005 with М=8.5 . Aftershocks from these catastrophic earthquakes covered the area from the south-east to the north-west with length of 1500 km. tracing Andaman-Nikobar rupture. Epicenter of reported here earthquake is located in the northern part of this rupture.
    Focal mechanism and seismic moment of the earthquake
         Focal mechanism solutions of this earthquake, which happened on August 10, 2009 at 19:55 GMT were obtained with TMC method in NEIC USA and USGS, they are presented in table 2 and shown on Fig. 5. This earthquake has occurred under prevailing action of expansion forces oriented in S-E direction. Nodal plane NP1 has N-E direction of propagation and is steeply falling (DP=64º), NP2 plane propagates almost along latitudinal direction and lays more flat (DP=38º), in comparison with NP1, the type of motion along both planes – fault with left side drift components along NP1 and right side components along NP2. The value of seismic moment Мо of this earthquake, which occurred on August 10, 2009 at 19:55 GMT in accordance with USGS makes 2.1* 10** 20 n*m, moment magnitude makes Mw = 7.5.
    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
    141326015 252296364-61192 38-133NEIC
  • NEIC - National Earthquakes Information Center of US Geological Service

    • Figure 5


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