Information message about catastrophic earthquake at the Western coast of Northern Sumatra on December 26, 2004.

     On December 26, 2004 the catastrophic earthquake has happened near the Western coast of Sumatra Island, Indonesia at 00:58 GMT with magnitude М=8.8. The earthquake originated destructive tsunami. Since 1964 (the earthquake on Alaska with М=8.5 ) this is the strongest earthquake.
     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 2 0 min after registration to the Ministry of Emergency of the Russian Federation (EMERCOM).
     Preliminary processing has been done with data from 37 stations, accurate processing - with data 39 stations.
     Fig. 1 presents fragments of records for this earthquake obtained from digital stations Ala-Archa (delta 43,5 degrees), Talaya (delta 48,6 degrees), Borovoe (delta 53,8 degrees), Garni (delta 58,8 degrees), South-Sakhalinsk (delta 59,4 degrees). Fig. 2 presents fragments of records for this earthquake obtained from digital stations Arti (delta 60.7 degrees), Kislovodsk (delta 61.8 degrees), Magadan (delta 70 degrees), Obninsk (delta 70 degrees), Petropavlovsk-Kamchatsky (delta 71.2 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 00-58-48.20 3.39 95.84  10  39  8.80/166.70/1512.5-1375 IPC GS RAS (accurate)
2 00-58-51.70 3.4 95.84  33  37  8.8/156.7/1510-1175 IPC GS RAS (preliminary)
3 00-58-50.70 3.5 95.72  10  288  Mw8.9 5.6-7.3/8 61 CSEM
4 00-58-50.76 3.298 95.778  10  157  8.5/386.3/55  NEIC (preliminary)
5 00-58-49.80 3.244 95.825  10  223  8.8/1106.4/66 29 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
    • Epicenter
         The catastrophic earthquake on December 26, 2004 has happened near the Western coast of Northern part of Sumatra Island, Indonesia. A whole bunch of the earthquakes has occurred along the same tectonic fault. The initial strike covered the Northern part of Sumatra Island, after that the series of strikes have been registered up to Nikobar and Andaman Islands. The huge приливная wave begun to spread in the different directions. The wall of water with height of 10 meters has fallen on the coasts of Sri Lanka, India, Indonesia, Thailand, Malaysia. From ITAR TASS data nearly 55 thousands of people have been killed by December 28, 2004.
    Aftershock
         This earthquake has been accompanied with numerous aftershocks. The Alert Survey has obtained parameters on 40 the most strongest of them (with Mb >5.5). Locations of aftershocks one can find on the figure.

    Figure 3
    Focal mechanism and seismic moment of the earthquake
         Focal mechanism solution of the earthquake 26.12.2004 has been calculated with TMC method in National Earthquakes Information Center, USA (NEIC) and in Harvard Center, USA (HARVARD) and is presented in table 2 and on figures 4, 5. Focal mechanism solutions obtained in different centers are close to each other. The motion in origin has occurred under the action of compression strengths with near the same values oriented to the South-West and expansion strengths oriented to the North-East. One nodal plane has South-East-North-West spread direction and steep falling angle. The type of motion - thrust. The other nodal plane was low angled and from NEIC data it was latitudinal oriented, while from Harvard data it had almost longitudinal spread direction. The type of motion along this plane - overthrust. The value of seismic moment Мо from NEIC data is 2.6* 10** 21 n*m, the value of moment magnitude - Mw = 8.2. The value of seismic moment Мо from HARVARD data is 3.95* 10** 22 n*m, the value of moment magnitude - Mw = 9.0.
    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
    554934213 73082741355130 7998NEIC
    523637221 31293298110129 8287HARVARD
  • NEIC - National Earthquakes Information Center of US Geological Service
  • HARVARD - Harvard Geophysical Center (USA)

    • Figure 4
    Figure 5


    News | Catalogs | Wave Forms | Alert Service | Software | Links | Srtucture | Publications | Conferences | Announce | About
    © FRC GS RAS 1993-2018