Information message on appreciable earthquake in a southeast of Siberia, in southern Yakutia, on November, 10, 2005.

     On November 10, 2005 an appreciable earthquake with magnitude М=5.6 has happened in a southeast of Siberia at 22:29 Moscow time (19:29 GMT). The epicenter was located in 60 km to the north from the settlement Olekma. This earthquake was felt in a number of settlements of southeast Siberia with intensity up to 3-4 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 43 min after registration to the Ministry of Emergency of the Russian Federation (EMERCOM).
     Preliminary processing has been done with data from 26 stations, accurate processing - with data 39 stations.
     Fig. 1 presents fragments of records for this earthquake obtained from digital stations Yakutsk (delta 6.5 degrees), Tiksi (delta 14.6 degrees), Seimchan (delta 16.6 degrees), Yuzhno-Sakhalinsk (delta 17.2 degrees), Bilibino (delta 23 degrees). Fig. 2 presents fragments of records for this earthquake obtained from digital stations Kurchatov (delta 25 degrees), Borovoe (delta 28 degrees), Arti (delta 33 degrees), Obninsk (delta 44 degrees), Garni (delta of 50 degrees).

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 19-29-53.000 57.54 120.46  10  39  5.60/126.00/135-645 IPC GS RAS (accurate)
2 19-29-52.80 57.54 120.44  10  26  5.6/116.0/105-675 IPC GS RAS (preliminary)
3 19-29-52.7 57.48 120.37  10  430  6.0Mw   56 CSEM
4 19-29-55.19 57.45 120.5  10  151  5.3/35.8/89 36 NEIC (accurate)
5 19-29-55.19 57.47 120.5  10  140  5.3/35.8/89 36 NEIC (preliminary)
6 19-29-58.61 57.37 120.89  30  75   5.8  300 ORFEUS
7 19-29-57.7 57.25 120.59    13  К14.7/7   BB SD GS RAS
  • 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
  • ORFEUS - Observatories and Research Facilities for EUropean Seismology
  • BB SD GS RAS - Baikal Branch of Siberian Division of GS RAS
    • Epicenter
         Epicentre of this earthquake is located at the northeast end of Udokan ridge between the rivers Charuody and Olekma. From the point of seismotectonic the area of this earthquake belongs to one of destructive zones of Olekmo-Stanovoy seismotectonic area of Southern Yakutia being east flank of Bajkalo-Stanovoy belt, which extends from Baikal lake in the West up to Okhotsk Sea in the east (Kozmin B.M., Petrov A.F., Timirshin K.V., Shibaev S.V. " Seismicity of destructive zones of Southern Yakutia ", Novosibirsk, 2005). Destructive zones of lithosphere include areas of its dissociation, areas of intensive stress condition, areas of high velocity deformations and contrast variations of geophysical field values. These zones are the most unstable areas of a terrestrial surface and represent territories of potential natural accidents (Sherman S.I., Irkutsk, 2004). The largest regional break within the area of Stanovoi zone is the same named sub latitudinal regional joint (fig. 3 - mark 4), separating Aldansky board of Siberian platform from Djugdjuro-Stanovoi folded area. A few destructive zones are available on Aldan board, on fig. 3 they are designated by letters. Origin place of reported here earthquake belongs to one of them – Temulyakitsk zone (symbol A on fig. 3). The greatest number of catastrophic earthquakes in accordance with Kozmina B.M., etc., 2005, with М=6-7 lays at the crossing of these destructive zones: Stanovoi (Д symbol on fig. 3) and Temulyakitsk (А), Stanovoi and Amginsk (B on fig. 3), etc. Earthquakes in this zone continue to confirm the seismicity of Baikal rift zones to the east from the middle length of Olekma river to Ugodoi lip of Okhotsk Sea.

    Figure 3
    Aftershock
         Activity in the area of reported here earthquake on November, 10, 2005 began earlier this year in September, when Alert Service of GS RAS registered the earthquake on September 14, 2005 at 13:48:38.9 with М=3.5. Before that moment Yakut Branch of GS RAS also registered separate pushes in this area in May, June and August which basically did not exceed 8-9 power classes, except only one strike on May 31 at 18:34 which had К=10.7. Foreshock events of this area include the earthquakes: on November 6 at 19:34:37.8 with М=3.5, and 4 pushes on November 10 at 02:0:58.5 with М=3.8, at 05:28:20.4 with М=3.5, at 06:34:33.2 with М=3.7, at 19:27:24.1 with mb=4.9. According to G.Grib from seismic station Nerjungri located approximately at 500 km from epicentre, 56 weak aftershocks have been registered by November 13. Alert Service of GS RAS reported that parameters of 5 strongest of them have been determined by November 13.
    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
    200529652005-11-10 21:06:24.057.65120.6107-4.9/ 25-5.5 Southeastern Siberia, Russia
    200529662005-11-11 06:12:50.057.66120.832063.6/ 1-3.5-4 Southeastern Siberia, Russia
    200529672005-11-11 11:40:39.057.37120.621073.8/ 1-5-5.5 Southeastern Siberia, Russia
    200529682005-11-11 13:52:04.057.51120.752064.0/ 1-4-4.5 Southeastern Siberia, Russia
    200529872005-11-13 05:15:44.057.65120.651073.7/ 2-5 Southeastern Siberia, Russia
    Macroseismic manifestations
         This earthquake on November 10, 2005 has happened in low populated area at the south of Yakut region. It was felt in settlements Hani and Olekma with intensity 3-4 MSK, in Chara Kuanda and Novaya Chara with intensity 2-3 MSK, in Chita with intensity 2 MSK.
    Historical records
         Operative seismological bulletin of GS RAS does not contain information about the earthquakes with magnitudes 6 and more in the region of the reported here earthquake (shown with arrow on fig.4) since 1955 up now despite the fact that this region was rather seismically active within the period specified above. Earthquakes with magnitudes М=6-7 have happened to the south-south-east: on January 18, 1967 in the area of Kalarsky ridge with М=7.0, on January 5, 1958 with М=6.5, on April 20, 1989 with М=6.6 and on May 17, 1989 with М=6.0, on September 14, 1958 with М=6.3 and on June 14, 1971 with М=5.9 (see fig.4).

    Figure 4
    Focal mechanism and seismic moment of the earthquake
         Focal mechanism solutions of this earthquakes origin, which happened on 10.11.2005 at 19:29 have been obtained in IPC GS RAS from the signs of first arrivals of P waves at 120 stations. At 15 of these stations they were registered as waves of compression - symbol "+", at 105 stations – as waves of expansion (symbol "-"). Table 2 presents elements of focal mechanism obtained by IPC GS RAS, as well as solutions published in Internet by NEIC and Harvard Center USA (HARVARD). Graphical representation in stereographical projection (lower hemisphere , waves of compression shown in dark) of focal mechanisms are shown on fig. 5-7 and presented in table 2. Solutions obtained by different centers are close to each other. Both nodal planes have north-west-south-east direction of propagation. Both planes lay rather steep. The investigated earthquake has happened under the action of expansion strength oriented to the north-east-south-west direction. Type of motion along both planes – normal trap drown. However Kozmin B.M. and others in their work "Seismisity of destructive zones of Southern Yakutia" mention, that in the transition area from Baikal rift zone to Olekmo-Stanovoi seismic active zone the change of geodynamic conditions from expansion to compression takes place. Nevertheless this is not observed in the reported earthquake. Thus, for the type of focal mechanism of it’s origin this earthquake 10.11.2005 more attracts to Baikal rift zone. The value of seismic moment Мо obtained in IPC GS RAS with data from 2 stations - OBN and ARU makes 1.7* 10** 18 n*m, the value of moment magnitude - Mw = 6.1. The value of seismic moment Мо obtained in NEIC makes 1.0* 10** 18 n*m, the value of moment magnitude - Mw = 6.0. The value of seismic moment Мо obtained in Harvard makes 2.1* 10** 17 n*m, the value of moment magnitude - Mw = 5.5.
    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
    11559235 281016542-135298 62-58IPC GS RAS
    202076911 611511366-96307 25-77NEIC
    43146126 4429715756-34268 63-141HARVARD
  • 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 5
    Figure 6

    Figure 7


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