Information message about sensitive earthquake in Okhotsk Sea on November 24, 2008 |
| On November 24, 2008 at 9:02 GMT (12:02 Moscow time) the deep sensitive earthquake with magnitude M=6.5 has occured in Okhotsk Sea. |
| 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 17 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 60 stations, accurate processing - with data 75 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Petropavlovsk (∆ 2.8º), Seimchan (∆ 8.8º), Erimo (∆ 14.3º), Bilibino (∆ 15º), Yakutsk (∆ 15.2º), Vladivostok (∆ 18.5º). Fig. 2 presents fragments of records obtained from digital stations Kurchatov(∆ 44.3º), Kingsbay (∆ 45.3º), Lovozero (∆ 50.3º), Obninsk (∆ 59.7º), Vasula (∆ 60º), Kislovodsk (∆ 66.3º). |
Figure 1
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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 |
09-02-57.4 |
54.19 |
154.44 |
490 |
75 |
6.5/17 | 6.9/21 | 4-5 | 45 | IPC GS RAS (Accurate) | | 2 |
09-02-57.4 |
54.17 |
154.45 |
490 |
60 |
6.5/17 | 6.9/21 | 4-5 | 50 | IPC GS RAS (Preliminary) | | 3 |
09-02-57.8 |
54.24 |
154.36 |
500 |
619 |
7.0Mw | | | 24 | CSEM | | 4 |
09-02-58.7 |
54.19 |
154.32 |
492 |
374 |
7.3Mw | 6.5/227 | | 22 | NEIC (Accurate) | | 5 |
09-02-58.4 |
54.18 |
154.31 |
487 |
235 |
| 6.6/66 | | | 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 depicts with blue color epicenter of this earthquake, which was located in Okhotsk Sea at 88 km from the western coast of Kamchatla Peninsula at the depth of 490 km, in 100 km of west from Sobolev Island, in 305 km of W-N-W from Petropavlovsk-Kamchatsky, in 415 km of N-N-W from Severo-Kurilsk, in 640 km of S-S-W from Magadan. |
Figure 3 |
|
| Aftershock |
| In 2 hours after the main shock GS RAS registered aftershock with М=4.5, and in 6.5 hours - aftershock with М=3.5. |
| 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 |
| 20083789 | 2008-11-24 11:01:43.0 | 54.02 | 154.23 | 490 | 16 | - | 4.5/ 2 | - | Sea of Okhotsk | | 20083790 | 2008-11-24 15:30:35.0 | 53.91 | 153.89 | 440 | 15 | - | 3.5/ 2 | - | Sea of Okhotsk | |
| Macroseismic manifestations |
| The earthquake was felt in Petropavlovsk-Kamchatsky with intensity 4, in Severo-Kurilsk with intensity 2-3. |
| Historical records |
| Epicenter of this earthquake was located in 100 km of E-N-E from deep sensitive earthquake registered on July 5, 2008 with М=7.2
|
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solution of this earthquake’s origin was calculated in IPC GS RAS from the first signs of P-wave arrivals at 170 stations, 81 of them registered the waves of compression (plus signs) and 89 of them registered the waves of expansion (minus signs). These stations are located in epicenter distances of Δ=2.7-160º from each other with rather uniform dispersion along azimuths. Origin’s solution in stereographical projection at the lower hemisphere is shown on figure 4. Fig. 5, 6 also present focal mechanism solutions of the origin in stereographical projection for the earthquake 24.11.2008, which were calculated with TMC technique in NEIC USA США, USGS USA and HRVD (Global CMT Catalog). Parameters of focal mechanism are presented in table 2. The obtained solutions are identical.
The earthquake has occurred under the action of close in value strengths of compression and expansion oriented of N-W–S-E (at rather insignificant prevailing of expansion).
Nodal plane NP1 has N-E direction of propagation and steep falling, with the right side slide components. Nodal plane NP2 spreads along latitudinal direction of propagation and lays flat, the type of motion – left side slide motion with uplift components.
The value of seismic moment Мо of the earthquake 24.11.2008 in accordance with USGS makes 1.09* 10** 20 n*m, the value of moment magnitude 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 |
| 39 | 127 | 51 | 299 |
4 | 33 | 33 | 84 | -94 | 247 |
7 | -56 | IPC GS RAS | | 34 | 138 | 51 | 286 |
16 | 37 | 34 | 81 | -106 | 276 |
18 | -29 | NEIC | | 35 | 136 | 51 | 288 |
13 | 36 | 35 | 82 | -103 | 275 |
16 | -30 | 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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