Information message on appreciable earthquake at the eastern coast of Honshu on November 14 2005.

     The appreciable earthquake has happened on November 14, 2005 at the eastern coast of Honshu, Japan at 21:38 GMT with magnitude М=7.1. The epicentre was located at 350 km to the east from Sendai city and about 535 km to the northeast from Tokyo – the capital of Japan. This earthquake was felt in a number of cities of the northeastern part of Honshu Island and caused mean amplitude wave of tsunami
     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 36 min after registration to the Ministry of Emergency of the Russian Federation (EMERCOM).
     Preliminary processing has been done with data from 23 stations, accurate processing - with data 39 stations.
     Fig. 1 presents fragments of records for this earthquake obtained from digital stations: Yuzhno-Sakhalinsk (delta 9 degrees), Petropavlovsk (delta 17.7 degrees), Magadan (delta 22 degrees), Yakutsk (delta 26 degrees), Bilibino (delta 32 degrees), Tiksi (delta 35 degrees). Fig. 2 presents fragments of records for this earthquake obtained from digital stations: Kurchatov (delta 47 degrees), Borovoe (delta 52 degrees), Arti (delta 57 degrees), Obninsk (delta 69 degrees), Kislovodsk (delta 72 degrees), Garni (delta 73 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 21-38-52.50 38.08 144.93  33  39  7.10/177.00/188-8.5107 IPC GS RAS (Accurate)
2 21-38-52.2 38.08 144.91  33  23  7.0/107.1/108-8.5107 IPC GS RAS (Preliminary)
3 21-38-49.9 38.14 144.95  10  321   7.2  36 CSEM
4 21-38-54.6 38.14 144.89  30  226  6.7/36.7/80 32 NEIC (Accurate)
5 21-38-53.9 38.17 144.85  24  133   6.8/86  NEIC (Preliminary)
  • 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
         In accordance with data of the National Earthquakes Information Center (NEIC) of the US Geological Service this earthquake has taken place in a zone of subduction, from external oceanic part of this zone. Most of the earthquakes here occur closer to the islands and a small density of the earthquakes is known for the zone of this earthquake (annual number of earthquakes per unit of the surface) in general, and the strong earthquakes in particular (fig. 3).

    Figure 3
    Macroseismic manifestations
         From NEIC data this earthquake was felt in 34 settlements of the northeastern part of Honshu Island, maximum intensity reached IV points on X point scale of intensity (fig. 4). This earthquake was felt on Kuril Islands in Malokurilskoe – with intensity 3 points on 12-point scale of seismic intensity MSK-64. From RIA news the wave of tsunami with 50 centimeters height has reached northern Pacific coast of Japan on Tuesday in the morning. Neither victims nor destructions are confirmed. The strongest tsunami has fallen upon this area of Japan in 1960 after the powerful earthquake in Chile. Then the wave has destroyed the city of Ofunato. After that breakwaters and high concrete walls have been constructed along the coast line.

    Figure 4
    Focal mechanism and seismic moment of the earthquake
         Focal mechanism solutions for this earthquake, which happened on 14.11.2005 at 21:38 GMT are presented in accordance with data obtained from the National Earthquakes Information Center (NEIC) of the US Geological Service. Graphical representation of focal mechanism is given on fig.5 in stereographic projection (lower hemisphere, waves of compression shown in black), elements of this mechanism are presented in table 2. Both nodal planes have north-east-south-west direction of propagation with rather deep depth. The reported earthquake has taken place under the action of expansion oriented in a southeast direction. Type of motion along both planes - normal trap drown. The value of seismic moment Мо obtained in IPC GS RAS with data from 3 stations - OBN, ARU, KIV makes 4.6*10 ** 19 n*m, the value of moment magnitude - Mw = 7.1. The value of seismic moment Мо obtained in NEIC makes 2.2*10 ** 19 n*m, the value of moment magnitude - Mw = 6.9.
    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
    1111176253 82021235-7514 56-100NEIC
  • NEIC - National Earthquakes Information Center of US Geological Service

    • Figure 5


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