Information message about the earthquake in Primorie on June 28, 2002

     On June 28, 2002 the deep strong earthquake has happened in Primorie (Russia-China, border area) at 21:19 Moscow time (at 17:19 GMT). It had magnitude mb=7.0.
     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 40 min after registration to the Ministry of Emergency of the Russian Federation (EMERCOM).
     Preliminary variant of the earthquake's parameters has been obtained with data from 12 stations. Waveforms from nine of them were obtained by IPC in a near to real time mode. Times of initial wave arrivals at three foreign stations – FINES in Finland, YKA in Canada and WRA - in Australia were obtained from data of International Data Center in Vienna. Accurate processing has been done with data from 34 stations, the nearest of them from Russia is Vladivostok station (distance 120 km), including analog stations of Russia, analog stations of seismic networks of CIS countries: Kirgizia, Uzbekistan, Turkmenia, Belorussia, Moldova, Ukraine. Besides them imformation has been obtained from some stations of China, South Korea, Mongolia.
     Figure 1 presents fragments of records from digital station South-Sahalinsk (delta 9. degrees), Yakutsk (delta 18.3 degrees), Talaya (delta 19.8 degrees), Magadan (delta 19.9 degrees), Petropavlovsk-Kamchatka (delta 20.5 degrees). Figure 2 shows records from digital stations Bilibino (delta 30.6 degrees), Arti (delta 45.9 degrees), Obninsk (delta 57.7 degrees), Pulkovo (delta 58.1 degrees), Kongberg, Norway (delta 63.5 degrees). Waveform picture is typical for deep earthquakes. It's analysis shows sharp P-wave initial arrivals and deep pP and sP phases at almost all stations. Besides that amlitude of volume waves records significantly exceeds amplitudes of surface waves of Relei. That fact confirms significant deepness of the origin.

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 17-19-30.20 43 130  570  34  6.30/97.00/112-366 IPC GS RAS (accurate)
2 17-19-29.4 43 130  570  12   6.8/6 127 IPC GS RAS (preliminary)
3 17-19-29.1 44 130  540  261   6.5-7.5  62 CSEM
4 17-19-29.8 43 130  555  194   6.5/90  NEIC (preliminary)
5 17-19-30.3 43 130  564  260   6.8/114 36 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
         The earthquake considered here has taken place at the big depth of the Earth's mantle. Therefore, despite of significant magnitude (mb=7.0), it's macroseismic effect on the surface was also significantly strong, however the area of sensitivity for this earthquake was rather big. From ITAR TASS data during 29.06.2002 this earthquake was felt in Russia in the following cities of Primorie: Ussuriysk, Vladivistok, Spas-Dalni, Arseniev and Artem - with intensity 2 MSK, and also in Chinese provinces Tzilin, Heilundzian, Liaonin located close to epicenter's area. Besides that ITAR TASS informed about it's registration in Beijing and provinces Shandun and Hanan, located at distance of 1 thousand kilometers to the South.
    Historical records
         This earthquake has taken place near the origin of the deep earthquake happened on April 8,1999, information about that event was published on our server earlier. Location of reported here earthquake is shown on the map (fig. 3) along with parameters of local deep origins known from Operative seismological bulletin (Obninsk) for the period 1955–2002.

    Figure 3
    Focal mechanism and seismic moment of the earthquake
         Focal mechanism of the earthquake 28.06.2002 at 17:19 has been calculated in CEME GS RAS with signs of initial arrivals of P-waves at 58 stations, which are located in the intervals of epicentral distances 1.1 - 96.2 degr. at rather uniform distribution along the azymuths. Building focal mechanism with signs of initial arrivals was done at good coverage of the origin place with stations and also with account of waveforms taken from global network IRIS, which were published on server: http://www.iris.washington.edu/SPYDER/spyderdata/data2002/0206281719/sum.html. Velocity of P waves at the depth of 570 km was taken as equal to 9.85 km/sec (Bolt, 1984). Parameters of the best solution are given in table 2, location of nodal planes in projection of the bottom halfsphere in on the figure 4. Here, for comparison one can find solutions of focal mechanisms of the earthquake 28.06.2002 calculated with TMC method in different centers - National Earthquakes Information Center, USA (NEIC) in HARVARD (USA), their parameters are also presented in table 2 and on figures 5-6. Rather good correspondence is seen for solutions based on the signs of initial arrivals and on TMC method. Focal mechanisms of the earthquake in Primorie on June 28, 2002 from data of IPC GS RAS (Fig.4), NEIC (Fig.5) and HARVARD (Fig.6). Focal mechanisms of the earthquake 28.06.2002 is almost a pure thrust. Location of one of the nodal planes from all solutions has near to meridian spread direction. The value of seismic moment Mo from HARVARD data makes 1.0*10**20 n*m (1.0*10**27 D-CM), the value of moment magnitude - Mw=7.3, from data of NEIC – Mo=8.9*10**19 n*m (8.9*10**26 D-CM)., the value of moment magnitude - Mw=7.3.
    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
    5110039277 18358780188 8491IPC GS RAS
    568833285 81904314124188 7982NEIC
    589632284 31922514104191 7787HARVARD
  • 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 4
    Figure 5

    Figure 6


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