Information message about strong earthquake in the central part of Kuril Islands ridge on January 15 2009. |
| The strong earthquake with M=7.6 has occured in central part of Kuril Islands ridge - southern part of Severo-Kurilsk district on January 15, 2009 at 5:49 p.m. GMT (20:49 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 15 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 62 stations, accurate processing - with data 70 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Yuzhno-Kurilsk (∆ 7.2º), Erimo (∆ 9.9º), Matsushiro (∆ 16.3º), Vladivostok (∆ 16.9º), Bilibino (∆ 22º), Talaya (∆ 33.4º). Fig. 2 presents fragments of records obtained from digital stations Arti (∆ 55.9º), Obninsk (∆ 66º), Vasula (∆ 66.8º), Kislovodsk (∆ 66.3º), Kiev (∆ 72.3º), Garni (∆ 73.6º). |
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 |
17-49-36.8 |
46.85 |
155.21 |
33 |
70 |
7.6/22 | 7/21 | 9 | 49 | IPC GS RAS (Accurate) | | 2 |
17-49-36.8 |
46.86 |
155.21 |
33 |
62 |
7.6/17 | 7/16 | 9 | 48 | IPC GS RAS (Preliminary) | | 3 |
17-49-38.1 |
46.93 |
155.25 |
40 |
553 |
7.4Mw | | | 39 | CSEM | | 4 |
17-49-39.1 |
46.86 |
155.15 |
36 |
368 |
7.5/185 | 6.8/279 | | 14 | NEIC (Accurate) | | 5 |
17-49-39.5 |
46.89 |
155.17 |
35 |
161 |
7.3Mw | 6.8/146 | | | 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 |
| Fig.3 presents epicenter of this earthquake with yellow star, which was located in central part of Kuril Ridge in the southern part pf Severo-Kurilsk district in Pacific Ocean at the depth of 33 km, 190km e-s-e from Rasshua island, 430 km to the south from Severo-Kurilsk, 731 km s-s-e from Petropavlovsk-Kamchatsky, 795 km e-n-e from Yuzhno-Kurilsk. |
Figure 3 |
|
| Aftershock |
| GS RAS registered 10 aftershocks with magnitudes from 3.7 to 5.2 within 10 hours after the main shock. |
| 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 |
| 20090218 | 2009-01-15 20:34:07.0 | 46.89 | 155.31 | 33 | 14 | - | 4.6/ 3 | 2.5-3 | East of Kuril Islands | | 20090219 | 2009-01-15 21:00:29.0 | 46.28 | 156.06 | 170 | 12 | - | 3.9/ 3 | - | East of Kuril Islands | | 20090220 | 2009-01-15 21:04:07.0 | 46.48 | 155.75 | 230 | 9 | - | 3.7/ 3 | - | East of Kuril Islands | | 20090221 | 2009-01-15 21:06:12.0 | 46.89 | 155.19 | 33 | 21 | - | 4.3/ 10 | - | East of Kuril Islands | | 20090222 | 2009-01-15 21:09:53.0 | 47.13 | 155.43 | 33 | 20 | - | 4.5/ 9 | 2-2.5 | East of Kuril Islands | | 20090223 | 2009-01-15 21:24:26.0 | 47.24 | 155.34 | 33 | 8 | - | 4.1/ 1 | - | East of Kuril Islands | | 20090224 | 2009-01-15 21:48:48.0 | 47.09 | 155.39 | 33 | 21 | - | 4.5/ 11 | 2-2.5 | East of Kuril Islands | | 20090225 | 2009-01-15 22:24:17.0 | 46.84 | 155.8 | 33 | 17 | - | 4.5/ 10 | 2-2.5 | East of Kuril Islands | | 20090228 | 2009-01-15 23:58:31.0 | 47.31 | 154.95 | 33 | 12 | - | 4.3/ 7 | - | Kuril Islands | | 20090229 | 2009-01-16 03:37:32.0 | 47.11 | 155.05 | 33 | 25 | - | 4.7/ 8 | 2.5-3 | East of Kuril Islands | |
| Macroseismic manifestations |
| This earthquake was felt in Petropavlovsk-Kamchatsky, Severo-Kurilsk, Yuzhno-Kurilsk, Malokurilsk with intensity 3 MSK. |
| Historical records |
| Epicenter of this earthquake of January 15, 2009 was located in origin zone of two strong earthquakes which happened on Kuril Islands - on November 15, 2006. and January 13, 2007 with М=8.2. Another earthquake has occurred here on March 3, 2008 with М=6.8. Fig. 4 presents seismic activity for 2006-2009 period in the region of Kuril Islands in accordance with information from Alert Survey of GS RAS. |
Figure 4 |
|
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solutions of the origin for the earthquake which happened on January 15, 2009 at 17:49 were obtained with TMC method in NEIC USA, USGS and Harvard Center USA, HRVD (Global CMT Catalog), they are presented on fig. 5,6. Solution obtained in IPC GS RAS from first arrivals of Р-waves (59 signs "plus", 27 - "minus") is depicted on fig. 7. The stations are located in the interval of epicentral distances of Δ=5-85º with rather uniform dispersion along azimuths. Elements of mechanisms are presented in table 2. These solutions obtained in different centers are very similar.
This earthquake occurred under the action of compression forces oriented N-W–S-E. Both nodal planes have N-E direction of propagation in solutions from USGS and HRVD,
For the case of Р-waves the nodal plane NP1 also propagates from the north-east to the south-west, while NP2 has nearly along meridian direction of propagation. Both nodal planes in all solutions are rather steeply falling. The type of motion along both nodal planes – uplift (with components of left side shift along NP1 plane and of right side shift along NP2 plane).
Averaged value of seismic moment Мо of the earthquake 15 15.01.2009 17:49 obtained ,from spectra of Р-waves at stations Talaya (Δ 33.4º), Arti (Δ 55.9º), Obninsk (Δ 66º), Kislovodsk (Δ 71.7º), makes 1.3* 10** 20 n*m, the value of moment magnitude calculated from Kanamori formula makes Mw = 7.4.
The value of seismic moment Мо in accordance with USGS makes 1.6* 10** 20 n*m, the value of moment magnitude Mw = 7.4; in accordance with HRVD – Mo= 1.5* 10** 20 n*m, Mw=7.4.
|
| 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 |
| 63 | 173 | 12 | 286 |
24 | 22 | 349 | 39 | 50 | 216 |
61 | 118 | IPC GS RAS | | 81 | 231 | 4 | 108 |
6 | 17 | 12 | 50 | 81 | 205 |
41 | 100 | NEIC | | 83 | 193 | 0 | 287 |
7 | 17 | 10 | 45 | 80 | 203 |
46 | 99 | HARVARD | |
| IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences |
| NEIC - National Earthquakes Information Center of US Geological Service |
| HARVARD - Harvard Geophysical Center (USA) |
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