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Information message about destructive earthquake near the eastern coast of Honshu Island of Japana on March 11, 2011.

     Destructive earthquake with M=8.8 has occurred near the eastern coast of Honshu Island of Japan on March 11, 2011 at 05:46 GMT (08:46 Moscow time). It caused victims and destructions.
     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 20 min after registration to the Ministry of Emergency of the Russian Federation (EMERCOM).
     Preliminary processing has been done with data from 64 stations, accurate processing - with data 70 stations.
     Fig. 1 presents fragments of records obtained from digital stations Yuzhno-Sakhalinsk (∆ 8.7º), Taejon (∆ 12.3º), Petropavlovsk (∆ 18.4º), Yakutsk (∆ 25.1º), Seimchan (∆ 25.4º). Fig. 2 presents fragments of records obtained from digital stations Bilibino (∆ 32.6º), Borovoe (∆ 50.5º), Arti (∆ 56.1º), Lovozero (∆ 61.4º), Obninsk (∆ 67.7º).

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 05-46-22.,2 38.29 142.69  33  70  8.8/237.2/3010.5-11  IPC GS RAS (Accurate)
2 05-46-22.,3 38.29 142.68  33  64  8.7/257.1/2710.5-11 78 IPC GS RAS (Preliminary)
3 05-46-23.8 38.3 142.5  21.9  641  Mw 8.9   29 CSEM
4 05-46-23.7 38.32 142.37  24.4  350  Mw 8.9 7.2/208 29 NEIC
  • 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
         Fig. 3 presents with red star epicenter of this earthquake which was located near the eastern coast of Honshu Island, Japan, at the depth of 33 km, 155 km east off Senadai, 330 km S-E off Aomori and 382 km N-E off Tokyo.

    Figure 3
    Aftershock
         This earthquake was accompanied with numerous aftershocks. GS RAS registered more than 90 aftershocks with M>5 within one day after the main shock. The table here presents 6 most significant of them with M>=6.6.
    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
    9092011-03-11 06:06:09.939.01142.373333-6.7/ 227.5-8 Near east coast of Honshu, Japan
    9102011-03-11 06:07:19.236.42141.963340-6.8/ 267.5-8 Near east coast of Honshu, Japan
    9112011-03-11 06:15:37.736.27140.933331-7.2/ 108.5-9 Near east coast of Honshu, Japan
    9122011-03-11 06:25:47.538.17144.631059-7.2/ 2810.5-11 Off east coast of Honshu, Japan
    9152011-03-11 06:58:58.537.42144.843347-6.6/ 237-7.5 Off east coast of Honshu, Japan
    9532011-03-11 11:36:40.539.39142.543361-6.8/ 137.5-8 Near east coast of Honshu, Japan
    Macroseismic manifestations
         In accordance with RIA-Novosti and Channel 1 this earthquake caused the powerful tsunami with ten meters height of the wave in some coast regions. In some prefectures tsunami crashed houses and cars on the roads. Huge wave has fallen on fields and roads destroying buildings. In accordance with latest information more than 50 thousand houses were partially or fully destroyed. Land and air traffic was interrupted on significant territory of the country. A few nuclear and thermal power plants were shut down. Tsunami water covered landing field of Sendai airport. The strong fires occurred at oil refineries, gas facilities and and steel works. Explosions were observed at NPP "Fukusima-1". Evacuation was started in 20 km area around nuclear power plant. No increase of radiation level was observed in Russian part of Far East. All day round monitoring of radiation is under way in this region. Kyodo News reported about 5 thousand people missing in Japan after the earthquake and tsunami. Still there is no chance to contact with 10 thousand people in Minami Sanriku town, this is half of population in this place. These people are not included in official list of missing persons. They are considered as "persons not in contact" or as "persons, whose safety is not confirmed". It was impossible to confirm safety of 8 thousand people in Iwate prefecture. The number of people evacuated makes 450 thousand. There is a significant lack of drinking water, meals and gasoline in the disaster area. This tragedy forced Japanese Authorities ask for help from abroad. For the first time in history Russian rescue team was sent to Japan. This earthquake was felt on the territory of Russia in Kuril Islands: in Yuzhno-Sakhalinsk and Kurilsk - with intensity 4, in Malokurilsk - with intensity 3. Aftershock which occurred at 06:25 was felt in Yuzhno-Kurilsk with intensity 5, in Kurilsk - with intensity 4. Tsunami warning system sent alarm signal about the danger to Kurils Islands. Russian EMERCOM reported that 11 thousand people were evacuated from potential zone of flooding, all forces of rescue teams worked in the ready to action state. Tsunami was observed in the region of Kunashir Island (near Yuzhno-Kurilsk town) and near Shikotan and Iturup Islands with waves of two meters high. Fig. 5, downloaded from Web Site of NEIC USA , presents the map with intensities obtained from phone calls to 336 residents in 118 places.

    Figure 4
    Historical records
         In accordance with NEIC USA in June 15, 1896 it was registered the earthquake with M=8.5 in this region. That earthquake caused tsunami with waves of 25 meters height, it killed 27000 people. In the same region on March 2, 1933 it was observed another earthquake with magnitude M=8.4 in 178 km E-N-E off the reported here earthquake of March 11, 2011. That earthquake caused tsunami with waves of 28 metersd height, it killed 3000 people. On March 9, 2011, two days before the reported here catastrophic earthquake, this area was hit by another earthquake which occurred 44 km N-E with magnitude M=7.7.
    Focal mechanism and seismic moment of the earthquake
         Focal mechanism solution for this earthquake which occurred on March 11, 2011 at 05:46 GMT was calculated in IPC GS RAS with first signs of initial arrivals of P-waves at 97 stations, including 81 stations which registered the waves of compression (plus signs), and 16 stations which registered the waves of expansion (minus signs). These stations are located in the interval of epicentral distances of 3º-83º with rather uniform distribution along the azimuths. Focal mechanism solution in stereographic projection at lower hemisphere is shown in figure 4, elements of this solution are presented in table 2. Table 2 and figures 5, 6 also present the solutions obtained with CMT technique in NEIC USA, USGS. All solutions are almost identical. This earthquake occurred under the action of both expansion and compression forces oriented N-W-S-E. Nodal plane with N-E direction of propagation is steeply falling (DP=78º–84º),the type of motion along it – uplift with component of right side slip. Another plane is flat and propagates from N-W to S-E, the type of motion along it – overthrust with left side slip component (DP=17º-19º). Seismic moment of this earthquake which occurred on March 11, 2011 was calculated in IPC GS RAS with spectra of Š-waves obtained at four stations: «Talaya» (∆ 30.27º), «Arti» (∆ 56.09º), «Obninsk» (∆ 67.69º), «Kislovodsk» (∆ 70.84º), it makes Mo=3.5*10**21 n*m. Averaged value of moment magnitude Mw was calculated with Kanamori formula and makes Mw=8.3. The value of seismic moment of this earthquake which occurred on March 11, 2011 in accordance with USGS makes Mo=2.8*10**22 n*m and the value of moment magnitude makes Mw=8.9.
    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
    4832236107 18210141191933 84108IPC GS RAS
    5531332108 11205162174528 78102NEIC
  • IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences
  • NEIC - National Earthquakes Information Center of US Geological Service

  • Figure 5

    Figure 6
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