Information message about the tangible earthquake in the Kuril Islands, July 7, 2015 |
| Sensitive earthquake M=6.4 occurred on July 7, 2015 at 05:10 GMT (8:10 Moscow time) in the Kuril Islands. |
| 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 9 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 32 stations, accurate processing - with data 57 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Kurilsk (∆ 1.3º), Yuzhno-Kurilsk (∆ 1.7º), Erimo (∆ 4.1º), Yuzhno-Sakhalinsk (∆ 4.9º), Matsushiro (∆ 10.6º). Fig. 2 presents fragments of records obtained from digital stations Mys Shultsa (∆ 12.5º), Magadan (∆ 15.8º), Tiksi (∆ 29.4º), Borovoe (∆ 50º), Obninsk (∆ 65.6º). |
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 |
05-10-24.9 |
43.92 |
148.19 |
50 |
57 |
6.4/13 | 6.8/23 | 6.5-7 | 126 | IPC GS RAS (Accurate) | | 2 |
05-10-36.4 |
43.86 |
148.32 |
100 |
32 |
| 6.3/20 | 5-5.5 | | IPC GS RAS (Preliminary) | | 3 |
05-10-26.0 |
43.99 |
147.98 |
30 |
410 |
Mw 6.3 | | | 33 | CSEM | | 4 |
05-10-27.3 |
43.99 |
147.94 |
38.1 |
159 |
Mw 6.3/27 | 6.4/307 | | 33 | 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 the epicenter of this earthquake, its origin was located in Pacific Ocean near the East coast of Kuril Islands, at the depth of 50 km, 108 km E of Malokurilskoye, 150 km SSE of Kurilsk, 188 km ESE of Yuzhno-Kurilsk. |
Figure 3 |
|
| Macroseismic manifestations |
| According to GS RAS this earthquake was felt in Gorny and Goriachy Plyazh with intensity 5-6 MSK, in Kurilsk, Reidovo and Kitovy with intensity 5 MSK, in Malokurilsk, Yuzhno-Kurilsk, Goriachy Klyuch, Golovnino, Mendeleev and Lagunny with intensity 4 MSK. |
| Historical records |
| The epicenter of this earthquake was located 93 km SW of the epicenter of strong earthquake July 20, 2014 М=5.9. |
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solution was obtained in IPC GS RAS with signs of initial arrivals of P waves at 75 stations, including 58 stations which registered compression waves (plus symbol) and 17 stations which registered tensile waves (minus symbol). These stations are located in the interval of epicentral distances 4–95º and in azimuth sector Az=5-355º. Focal mechanism in stereographic projection at lower hemisphere is shown in fig. 4. The elements of the mechanism are given in table 2. Fig. 5, 6 give focal mechanism solutions obtained in the National Earthquake Information Center of US Geological Service, USGS NEIC with Body-wave Moment Tensor (Mwb) technique and in Quick CMT Catalog Center, USA with CMT technique. All solutions from different centers are close.
This earthquake has occurred under prevailing action of compression stresses oriented south-east. Nodal plane NP1 in all solutions is nearly vertical (DP=70-73º), plane NP2 – flat (DP=21-35º). Nodal plane NP1 in all solutions strikes N-E (STK=47-56º), nodal plane NP2 strikes S-E in GS RAS and СМТ solutions (STK=162-173º) and S–W (STK=222º) in USGS solution.
The type of motion for NP1 plane – reverse fault with a small right lateral slip component, for NP2 – left lateral slip with reverse fault components in case of IPC GS RAS and СМТ and the thrust with left lateral slip components in case of USGS. The seismic moment of the earthquake, obtained in IPC GS RAS with spectra of P waves at the station «Talaya» (∆30.48º) makes Мо=2.2*10**18 N*m, Mw=6.2, according to the data obtained at the station "Obninsk" (∆65.62º) Мо=4.5*10**18 N*m, Mw=6.4; according to USGS NEIC – Mo=3.794*10**18 N*m, Mw=6.32; according to СМТ – Mo=3.61*10**18 N*m, Mw=6.3. |
| 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 |
| 51 | 353 | 22 | 113 |
30 | 217 | 47 | 73 | 121 | 162 |
35 | 30 | IPC GS RAS | | 65 | 334 | 25 | 142 |
5 | 234 | 56 | 70 | 95 | 222 |
21 | 77 | NEIC | | 57 | 347 | 23 | 118 |
22 | 218 | 46 | 71 | 113 | 173 |
30 | 40 | 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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