Information message about the strong earthquake in central part of Kuril ridge on November 15, 2006.

     The strong earthquake with M=8.2 has happened on November15, 2006 at 11:14 GMT in the central part of Kuril ridge –the Northern part of Simushir–Urupinsk region oa Kurilo-Okhotsk area. This earthquake has happened in the zone of "seismic gap", where in accordance with long term seismic forecast (Dr. Fedotov S.A.) it was expected the earthquake with М>7.7.
     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 40 min after registration to the Ministry of Emergency of the Russian Federation (EMERCOM).
     Preliminary processing has been done with data from 27 stations, accurate processing - with data 40 stations.
     Fig. 1 presents fragments of records obtained from digital stations Yuzhno-Sakhalinsk (∆ 5.8º), Petropavlovsk (∆ 7.3º), Seimchan (∆ 16.3º), Yakutsk (∆ 20.4º), Bilibino (∆ 22.5º). Fig. 2 fragments of records obtained from digital stations Borovoe (∆ 51º), Ala-Archa (∆ 53.9º), Arti (∆ 55.1º), Obninsk (∆ 65.4º), Garni (∆ 72.7º).

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 11-14-14.2 46.66 153.2  28  40  8.2/146.4/1810-10.5129 IPC GS RAS (Accurate)
2 11:14:14.5 46.62 153.25  33  27  8.2/116.3/129.5-10129 IPC GS RAS (Preliminary)
3 11:14:16.0 46.84 153.36  33    7.7    CSEM
4 11:14:16.76 46.683 153.224  28    8.3Mw 6.7/76  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
         Seismic activity in the center of Kuril ridge has intensified at the end of the third quarter of 2006 and was characterized by the series of the earthquakes with magnitudes М≥5 (fig.3). Fig. 3 depicts allocation of the earthquakes in the origin zone of the reported here earthquake since January 1, 2006. The strongest earthquakes have happened here on September 28 and 30, November1, October 13 and November 12. Besides that more than 80 weak earthquakes with mb≥4.5 have happened in this region, they are shown in violet color on fig.4. It is necessary to mention that 1 minute before the main shock it was registered the foreshock in the same region at 11h13m35.9s(utc) 46.48n 153.22e H=33 with magnitude mb=5.3. Emission of seismic energy at the origin in time is presented on fig.5, which presents cumulative diagram of seismic energy emission in the investigated area in accordance with data of Alert Service of RAS. Position of the main shock is shown on fig. 4 and fig.6 as the red star with potentially dangerous areas in the background. Fig.6 has been taken from monograph of Dr. Fedotov S.A. called "Long term seismic forecast for Kurilo-Kamchatka bow", 2005. It contains origin zones of the strong (М ≥ 73/4) earthquakes which happened in Kurilo-Kamchatka area in 1904 – 1963 as well as potential places of the future earthquakes with Μ ≥73/4 in accordance with Dr.Fedotov S.A., 2005. Legend to the figure 6: 1 – instrumental epicenters of the strong earthquakes; 2 –border areas of the origin zones of the strong earthquakes; 3 – unconfident border areas of the origin zones; 4 – potential origin zones; 5 – supposed origin zones of catastrophic earthquakes of the previous century; 6 – aftershocks of the earthquake 1.V 1915; 7 – aftershocks of the earthquake 30.I 1917., 8 – aftershocks of the earthquake 7.ΙΧ 1918.; 9 – aftershocks of the earthquake 3.II 1923.; 10 – strong foreshocks of the earthquakes 1923 and 1963; 11 – margins of tsunami areas; 12 – most probable places of future earthquakes with Μ ≥ 73/4; 13 – less probable places of future earthquakes with Μ ≥ 73/4; 14 – origin line of measuring distances along exit area of focal zone at the bottom of Pacific Ocean; 15 – axis of deep underwater depression; 16 – axes of Kurilo-Kamchatka volcanic belt.

    Figure 3
    Figure 4

    Figure 5
    Figure 6
    Aftershock
         This earthquakes has been accompanied with numerous aftershocks (fig.4). The strongest of them (М>=5.5) are shown on fig.4 with yellow rounds and are presented below:
    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
    200634362006-11-15 11:28:42.046.57153.833316-6.4/ 96.5-7 Kuril Islands
    200634382006-11-15 11:29:22.046.38154.423319-6.2/ 76-6.5 East of Kuril Islands
    200634372006-11-15 11:34:59.046.74155.463322-6.7/ 97.5-8 East of Kuril Islands
    200634392006-11-15 11:40:56.046.47154.773325-6.7/ 107.5-8 East of Kuril Islands
    200634402006-11-15 12:09:18.047.35155.533319-5.8/ 85.5 East of Kuril Islands
    200634462006-11-15 13:38:23.047.09155.323317-5.6/ 85 East of Kuril Islands
    200634502006-11-15 15:11:57.046.31154.163323-5.5/ 74.5-5 East of Kuril Islands
    200634522006-11-15 15:19:34.046.1154.23314-5.6/ 85 East of Kuril Islands
    200634622006-11-15 19:25:26.047.08154.893324-6.0/ 106 Kuril Islands
    200634632006-11-15 19:28:10.047.56154.553320-5.7/ 105-5.5 Kuril Islands
    200634682006-11-15 21:17:08.046.86154.723324-5.7/ 95-5.5 East of Kuril Islands
    200634692006-11-15 21:22:21.047.3154.143327-6.2/ 106-6.5 Kuril Islands
    200634702006-11-15 21:31:24.047.52154.073323-5.7/ 105-5.5 Kuril Islands
    200634732006-11-15 22:06:59.046.26153.143317-5.6/ 85 Kuril Islands
    200634862006-11-16 06:20:18.046.34154.4610326.1/ 146.1/ 128.5-9 East of Kuril Islands
    Macroseismic manifestations
         This earthquakes has been felt in Kurilsk with intensity 3-4 MSK, in Severo-Kurilsk with intensity 3 MSK, in Yuzhno-Kurilsk 2-3 with intensity MSK.
    Focal mechanism and seismic moment of the earthquake
          Focal mechanism solution of the earthquake 15.11.2006 has been calculated in GS RAS from the first signs of Р-wave arrivals at 49 stations, while 36 of these stations have registered the waves of compression (plus signs), the other 13 stations have registered the waves of expansion (minus signs). The stations are installed at epicentral distances of 8-71 degrees with rather uniform distribution along the azimuths. Fig.7 contains focal mechanism solution in stereographical projection at the lower hemisphere. Figures 8, 9 present focal mechanism solutions obtained from TM method in NEIC, USA and from CMT method in Harvard Center, USA. Elements of focal mechanism are presented in table 2. As one can see both solutions obtained from different methods are close. The motion in origin has happened under the action of prevailing compression forces oriented to the south-south-eastern direction. Type of motion in the origin along the flat latitudionally oriented NP1 plane is presented by the thrust. Type of motion in the origin along the steep falling NP2 plane with north-east orientation corresponding with spread direction of Kurilo-Kamchatka ridge is presented by reverse. Seismic moment Мо of the earthquake 15.11.2006 has been determined in GS RAS from spectra of Р-waves registered by digital equipment IRIS installed at seismic stations Arti (ARU), Obninsk (OBN) and Kislovodsk (KIV), located at the distances 55, 65 and 71 degrees respectively. Averaged value Мо made 4.6Е 20 n*m. The value of moment magnitude Mw calculated from Kanamori formula is equal to Мw=7.7. Seismic moment Мо of the earthquake 15.11.2006 in accordance with NEIC made 8.7Е 20 n*m. The value of moment magnitude Mw is equal to Мw=7.9. Seismic moment Мо of the earthquake 15.11.2006 in accordance with HRVD made 3.37Е 21 n*m. The value of moment magnitude Mw is equal to Мw =8.3. As one can see, the values of Мо and Мw obtained from different methods also are close and are within the range of permitted error.
    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
    5029738136 9392741114638 8481IPC GS RAS
    5831631155 8602701612158 7681NEIC
    6030230123 033214159233 7590HARVARD
  • IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences
  • NEIC - National Earthquakes Information Center of US Geological Service
  • HARVARD - Harvard Geophysical Center (USA)

    • Figure 7
    Figure 8

    Figure 9


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