Information message about the strong earthquake in the Kuril Islands, April 19, 2013 |
| The strong earthquake with M=6.9 has occurred in the Kuril Islands on April 19, 2013 at 3:05 GMT (7:05 Moscow time). |
| 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 11 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 54 stations, accurate processing - with data 62 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Yuzhno-Kurilsk (∆ 4.2º), Severo-Kurilsk (∆ 5.7º), Yuzhno-Sakhalinsk (∆ 5.7º), Erimo (∆ 6.9º), Petropavlovsk (∆ 8.5º). Fig. 2 presents fragments of records obtained from digital stations Tiksi (∆ 27.6º), Talaya (∆ 31.1º), Borovoe (∆ 50.1º), Arti (∆ 54.4º), Obninsk (∆ 64.9º).
|
Figure 1
| 
Figure 2
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|
| 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 |
03-05-51.0 |
46.12 |
150.91 |
120 |
62 |
6.9/27 | 7/22 | 7 | 82 | IPC GS RAS (Accurate) | | 2 |
03-05-51.0 |
46.13 |
150.92 |
120 |
54 |
| 7/20 | 7 | 82 | IPC GS RAS (Preliminary) | | 3 |
03-05-51.9 |
46.259 |
150.889 |
100 |
569 |
Mw 7.2 | | | 36 | CSEM | | 4 |
03-05-53.6 |
46.182 |
150.796 |
122.3 |
107 |
Mw 7.2 | | | 36 | 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 origin was located in the Kuril Islands region, at the depth of 120 km, 260 km E-N-E of Kurilsk and 637 km S-W of Severo-Kurilsk. |
Figure 3 |
|
| Macroseismic manifestations |
| In accordance with GS RAS this earthquake was felt in Malokurilsk with intensity 4-5, in Kurilsk, Yuzhno-Kurilsk, Mendeleevo, Lagunnoe, Golovnino with intensity 4, in Severo-Kurilsk with intensity 3, in Yuzhno-Sakhalinsk with intensity 2. |
| Historical records |
| The last strong earthquake in the Kuril Islands region has occurred on April 7, 2009 55 km E of epicenter of earthquake April 19, 2013 and it was felt with intensities 3-4.
Fig. 4 presents the strong earthquakes of 2006-2013 which occurred in Kuril Islands region in accordance with Alert Service of GS RAS. |
Figure 4 |
|
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solution of the origin of this earthquake was calculated in IPC GS RAS with signs of initial arrivals of P-waves at 200 stations, including 163 stations which registered the waves of compression (plus signs) and 37 stations which registered the waves of expansion (minus signs). These stations are located in the interval of epicentral distances of 5–95º and dispersed evenly along the azimuths. Focal mechanism of the origin in stereographic projection at the lower hemisphere is presented at figure 5, elements of this mechanism are presented in table 2. Fig. 6, 7 present focal mechanisms obtained in NEIC USGS with method of USGS Centroid Moment Solution and obtained in Quick CMT Catalog, USA with CMT technique. Both solutions are identical. The earthquake has occurred under the action of close in value strengths of compression oriented S-E, and strengths of expansion oriented to the north. One nodal plane is nearly vertical (DP=83-84º), it propagates south-west, another plane is rather flat (DP=16-29º) and propagates south-east. The type of motion is fault along vertical plane and left hand slip with fault components along the flat plane.
The seismic moment in accordance with USGS NEIC Мо=1.1*10**20 N*m, the value of moment magnitude calculated with Kanamori formula Mw=7.3. In accordance with Quick CMT Мо=9.7*10**19 N*m, 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 |
| 33 | 9 | 44 | 138 |
28 | 259 | 155 | 29 | -12 | 256 |
84 | -118 | IPC GS RAS | | 38 | 347 | 49 | 138 |
15 | 245 | 133 | 16 | -22 | 244 |
84 | -105 | NEIC | | 36 | 350 | 49 | 136 |
17 | 247 | 134 | 19 | -22 | 245 |
83 | -108 | Quick CMT | |
| IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences |
| NEIC - National Earthquakes Information Center of US Geological Service |
| Quick CMT - Quick CMT catalog |
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