Information message about destructive earthquake at the western coast of Solomon Islands on April 01, 2007.

     The strong destructive earthquake with М=7.8 has taken place on April 1 at 8:39 p.m. GMT (on April 2 at 00:39 Moscow time) at the western coast of Solomon Islands. It caused tsunami with 5 meter waves in height and resulted in human 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 35 min after registration to the Ministry of Emergency of the Russian Federation (EMERCOM).
     Preliminary processing has been done with data from 16 stations, accurate processing - with data 25 stations.
     Fig. 1 presents fragments of records obtained from digital stations Erimo (∆ 51.7º), Yuzhno-Sakhalinsk (∆ 56.5º), Petropavlovsk (∆ 61.1º), Magadan (∆ 67.9º), Seimchan (∆ 71.2º), Yakutsk (∆ 73.3º). Fig. 2 presents fragments of records obtained from digital stations Talaya (∆ 75º), Bilibino (∆ 77º), Tiksi (∆ 82º), Kurchatov (∆ 89º), Ala Archa (∆ 90º), Arti (∆ 101º).

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 20-39-54.2 -8.34 156.93  10  25  7.8/206.5/911-11.5184 IPC GS RAS (Accurate)
2 20-39-53.6 -8.39 157  10  16  7.7/86.5/711219 IPC GS RAS (Preliminary)
3 20-39-55.2 -8.33 156.92  10  170  7.9Mw   31 CSEM
4 20-39-56.2 -8.47 156.95  10  148  7.6Mw 6.9/94 43 NEIC (Preliminary)
5 20-39-56.3 -8.45 156.96  10  152  8.0Mw 6.9/97 43 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
         Epicenter of this earthquake was located in Pacific Ocean at 40 km to the south -south-east from Gizo town and at 345 km to the west-north-west from Honiar town - the Capital of Solomon Islands. Fig.3 shows the location of epicenter in accordance with data from USGS NEIC

    Figure 3
    Aftershock
         This earthquake was accompanied with numerous aftershocks. Most significant of them in accordance with GS RAS information are shown below.
    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
    200712522007-04-01 20:47:33.0-7.29155.543316-6.4/ 56.5-7 Solomon Islands
    200712532007-04-01 21:03:04.0-7.65155.593311-5.7/ 75-5.5 Solomon Islands
    200712542007-04-01 21:11:35.0-7.31155.783324-6.5/ 67-7.5 Solomon Islands
    200712552007-04-01 21:15:24.0-7.34155.83313-6.2/ 86-6.5 Solomon Islands
    200712562007-04-01 21:25:07.0-8.39157.773312-5.5/ 54.5-5 Solomon Islands
    200712752007-04-01 21:43:15.0-7.51155.761015-5.6/ 96.5-7 Solomon Islands
    200712572007-04-01 21:45:39.0-7.19155.533319-6.0/ 96 Solomon Islands
    200712582007-04-01 22:29:53.0-7.63155.633313-5.3/ 74-4.5 Solomon Islands
    200712592007-04-01 22:57:24.0-7.54155.853319-5.7/ 95-5.5 Solomon Islands
    200712602007-04-01 23:09:37.0-7.86155.873316-5.3/ 74-4.5 Solomon Islands
    200712612007-04-01 23:25:28.0-7.44156.243318-5.2/ 84-4.5 Solomon Islands
    200712622007-04-02 00:10:53.0-7.58156.383315-5.2/ 64-4.5 Solomon Islands
    200712632007-04-02 00:49:49.0-6.76155.573311-5.2/ 74-4.5 Solomon Islands
    200712642007-04-02 01:31:05.0-7.82156.973312-5.4/ 74.5 Solomon Islands
    200712652007-04-02 01:49:32.0-7.53155.973311-5.2/ 54-4.5 Solomon Islands
    200712672007-04-02 04:03:19.0-7.65155.623312-5.1/ 63.5-4 Solomon Islands
    200712682007-04-02 04:11:41.0-7.22156.233314-5.6/ 85 Solomon Islands
    200712702007-04-02 05:30:46.0-7.34155.833312-5.4/ 84.5 Solomon Islands
    200712712007-04-02 05:33:35.0-6.87154.811016-5.8/ 107-7.5 Solomon Islands
    200712742007-04-02 07:16:30.0-7.49156.271018-5.6/ 76.5-7 Solomon Islands
    200712752007-04-01 21:43:15.0-7.51155.761015-5.6/ 96.5-7 Solomon Islands
    200712782007-04-02 10:49:13.0-7.62156.423318-5.9/ 85.5-6 Solomon Islands
    200712792007-04-02 12:02:25.0-8.41157.473316-6.0/ 76 Solomon Islands
    200712812007-04-02 12:35:26.0-8.77157.583311-5.2/ 84-4.5 Solomon Islands
    Macroseismic manifestations
         This earthquake caused the powerful wave of tsunami. The height of this wave was between 2 and 5 meters and in traveled 200 meters inside the islands shore. As a result of tsunami the towns Noro and Gizo have been completely flooded. Russian Information News reported that "the number of confirmed victims of tsunami in the southern part of Pacific Ocean by the night time reached not less than 21 persons. About 30 thousand persons suffered from this natural disaster. 3 thousand persons lost their homes. Total population of Solomon Islands is about 430 thousand people.
    Focal mechanism and seismic moment of the earthquake
         Focal mechanism solution of the earthquake 01.04.2007 has been calculated with CMT method in Harvard Center, USA (HARVARD). It is presented in table 2 and figure 4. The earthquake has happened under the action of compression oriented to the south-west. Both nodal planes have rather steep falling angle (DP=38-58°) and are oriented to the north-west-south-east direction of propagation, corresponding with orientation of Solomon Islands. The type of motion in origin – uplift (with components of shift – right sided along NP1, left sided along NP2). The value of seismic moment Мо determined from Р-wave spectra at station TLY (∆=75.3°) makes 4.5* 10** 20 n*m, the value of moment magnitude determined from Kanamori equation makes Mw = 7.7. The value of seismic moment Мо determined in HARVARD makes 1.60* 10** 21 n*m, the value of moment magnitude makes Mw = 8.1.
    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
    6933911220 1812633138120115 5869HARVARD
  • HARVARD - Harvard Geophysical Center (USA)

    • Figure 4


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