Information message about the strong earthqauke in Sea of Okhotsk, May 24, 2013 |
| The strong earthquake with m=7.7 has occurred in Sea of Okhotsk on May 24, 2013 at 05:44 GMT (09:44 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 41 stations, accurate processing - with data 54 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Petropavlovsk (∆ 3.7º), Severo-Kurilsk (∆4.5º), Magadan (∆ 4.9º), Seimchan (∆ 8.1º), Kurilsk (∆ 10.3º). Fig. 2 presents fragments of records obtained from digital stations Arti (∆ 49.3º), Pulkovo (∆ 57º), Obninsk (∆ 58.8º), Kislovodsk (∆ 65.3º), Garni (∆ 67.6º).
|
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 |
05-44-47.9 |
54.89 |
153.34 |
600 |
54 |
| 7.7/20 | 6-7 | 44 | IPC GS RAS (Accurate) | | 2 |
05-44-48.5 |
54.89 |
153.54 |
600 |
41 |
| 7.7/11 | 6-7 | 44 | IPC GS RAS (Preliminary) | | 3 |
05-44-48.5 |
54.924 |
153.296 |
598.7 |
324 |
Mw 8.1 | | | 23 | CSEM | | 4 |
05-44-49.0 |
54.871 |
153.335 |
601.8 |
99 |
Mw 8.2 | | | 25 | 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 Sea of Okhotsk at the depth of 600 km, 186 km W-N-W of Sobolevo, 405 km N-W of Petropavlovsk-Kamchatsky, 545 km S-S-E of Magadan and 700 km East of Okha. |
Figure 3 |
|
| Aftershock |
| GS RAS registered 2 aftershocks with M≥4.5 within 5 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 |
| 20131981 | 2013-05-24 07:32:03.0 | 55.02 | 153.62 | 600 | 29 | - | 4.6/ 9 | - | Sea of Okhotsk | | 20131985 | 2013-05-24 07:49:44.0 | 53.55 | 154.16 | 500 | 15 | - | 4.5/ 5 | - | Sea of Okhotsk | |
| Macroseismic manifestations |
| According to GS RAS the earthquake was felt in Petropavlovsk-Kamchatsky and Severo-Kurilsk with intensity 5-6, in Kronoki with intensity 5, in Apache, Elizovo, Termalny, Paratunka, Vilyuchinsk, Krutoberegovo with intensity 4-5, Ust-Bolsheretsk, Ganaly, Milkovo, Razdolny, Pauzhetka, Nikolskoe (Bering Island) with intensity 4, Bulkanny, Kozyrevsk, Kluchi with intensity 3-4, in Malokurilskoe, Kholmsk with intensity 3, in Yuzhno-Sakhalinsk, Magadan, Khabarovsk, Blagoveshchensk, Krasnoyarsk, Kazan, Okha with intensity 2-3, in Moscow, St. Petersburg, Nizhny Novgorod, Nivrovo, Nogliki with intensity 2 MSK.
|
| Historical records |
| The last deep strong earthquakes in the region Sea of Okhotsk have occurred on July 5 and November 24, 2008.
Epicenter of this earthquake was located 116 km N-N-E of the earthquake on July 5, 2008 with mb=7.2 and 107 km N-W of the earthquake on November 24, 2008 with mb=6.9
|
Figure 4 |
|
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism of the earthquake is calculated at the IPC GS RAS by the signs of P-wave first arrivals at 156 stations, of which 108 recorded a compression wave (the plus sign) and 48 stations recorded an expansion wave (minus signs). The stations are located in the range of epicentral distances of 3-92º and evenly by azimuth. Focal mechanism in stereographic projection on the lower hemisphere is shown in Fig.5, its elements are shown in Table 2. Fig. 6, 7 demonstrate the focal mechanism according to the National Earthquake Information Center of U.S. Geological Survey (USGS NEIC) based on centroid moment technique (USGS Centroid Moment Solution) and Quick CMT Catalog, the U.S., calculated by the centroid moment tensor method. The solutions are similar. The earthquake occurred under the dominance of a tensile stress oriented to the east. In compressive stress the vertical component dominates, and the horizontal component is oriented to the west. Nodal plane NP1 of meridional strike (STK=2-15º) is vertical (DP=79-84º) in all solutions, the second plane NP2 is flat (DP=9-17º), with southeast strike according to IPC GS RAS and south strike according USGS NEIC and Quick CMT solutions. The type of movement on the steep plane NP1 is a normal fault in all decisions and on the flat plane NP2 – a low-angle fault according to the NEIC and Quick CMT and a strike-slip with low-angle fault component according to the IPC GS RAS. According to the USGS NEIC Mo=4.4*10**21 N*m, Mw=8.4, according to the Quick CMT Mo=4.11*10**21 N*m, Mw=8.3 |
| 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 |
| 37 | 78 | 49 | 288 |
15 | 180 | 2 | 84 | -75 | 113 |
17 | -158 | IPC GS RAS | | 36 | 102 | 54 | 288 |
3 | 194 | 15 | 81 | -87 | 177 |
10 | -107 | NEIC | | 34 | 103 | 56 | 284 |
0 | 193 | 13 | 79 | -90 | 191 |
11 | -92 | 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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