Information message about the earthquake in Primorie on February 2, 2002

     On February 2, 2002 the deep earthquake has happened in Primorie (Russia) at 00:55 Moscow time (February 01, 2002 at 21:55 GMT). It had magnitude Mb=6.0.
     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 60 min after registration to the Ministry of Emergency of the Russian Federation (EMERCOM).
     Preliminary summary processing of this earthquake has been done with data from 16 stations, accurate processing - from 23 stations. Information was obtained by IPC from digital stations in a near to real time mode.
     Figure 1 presents fragments of records from digital stations South-Sahalin (delta 4.4 degrees), Petropavlovsk-Kamchatka (delta 16 degrees), Magadan (delta 16.3 degrees), Yakutsk (delta 16.9 degrees), Talaya (delta 22.5 degrees). Figure 2 presents fragments of records from digital stations Bilibino (delta 27.2 degrees), Borovoe (delta 42.5 degrees), Arti (delta 47.8 degrees), Obninsk (delta 59.2 degrees), Kislovodsk (delta 62.8 degrees). Presented here wave picture is typical for deep earthquakes. Analysis shows the presence of distinct initial P-wave arrivals at almost all stations and presence of deep phases рР and sP. Besides that, these records contain surface waves of Rayleigh.

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 21-55-21.50 45 136  360  20   6.00/12  IPC GS RAS (accurate)
2 21-55-22.5 45 136  360  16   5.9/10  IPC GS RAS (preliminary)
3 21-54-44.9 45 136  33  297   6.3-7.0   CSEM
4 21-54-45.2 45 136  33  134   6.3/72  NEIC (preliminary)
5 21-55-20.9 45 136  35  169   6.0/85  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
    • Macroseismic manifestations
         This earthquake has happened on February 2 at 7:55 local time. Its hypocenter was located in 350 km to the South-South-East from Habarovsk city. No information was obtained about destructive effects.
    Historical records
         The earthquake has happened in the region of Sihote-Alin mountain ridge. Historically the earthquakes with origin depths 300-460 km are known in this area. Most significant of them happened on January 30, 1918 with magnitude М=7.7 and on February 20, 1931 with magnitudeй 7.3. Total number of 14 deep origins are known here. Location of hypocenter for the the earthquake on February 02 (local time) 2002 is shown on the map (fig. 3). Depths are shown in different colors. Hypocenters of the earthquakes since 1900 till now are shown on the map in accordance with «Specialized catalogue» (ed. Dr. N.V.Kondorskaya, Dr.V.I.Ulomov, 1996) and seismic bulletin of CEME GS RAS for region with coordinates 40-50 N, 130-142E.

    Figure 3
    Focal mechanism and seismic moment of the earthquake
         Solutions of focal mechanism for the earthquake's origin 02.02.2002 have been calculated with TMC method (tensor moment cetroid) in different centers - National Earthquake Information Center, USA (NEIC) and in HARVARD center (USA). Their data are given in table 2 and are shown on figures 4-5. Focal mechanisms of the earthquake in Primorie Primorie on February 2, 2002 in accordance with NEIC (fig. 4) and HARVARD (fig. 5) data As it is seen the solutions obtained by different centers are almost the same. One nodal plane has near to latitudinal direction and steep falling angle, the other plane is oriented to the North-West slightly sloping. Type of motion along the steep plane is tripout. Motion in origin was under the action of both compressing and expanding strengths oriented along meridian. The value of seismic moment according to NEIC makes 1.0*10**18n*m (1.0*10**25 D-CM)., the value of moment magnitude - Mw=6.0. The value of seismic moment according to HARVARD makes 7.3*10**24 D-CM, the value of moment magnitude - Mw=5.8.
    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
    3418950333 188632920-2583 82-108NEIC
    3619347334 218734021-1685 84-111HARVARD
  • NEIC - National Earthquakes Information Center of US Geological Service
  • HARVARD - Harvard Geophysical Center (USA)

    • Figure 4
    Figure 5


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