Information message about the earthquake in Altai on September 27, 2003 | | On September 27, 2003 at 15 hours 33 minutes Moscow time (11:33 GMT) the strong earthquake with magnitude М=7.3 has happened here, with intensity IX in an epicentre and felt in settlements of high mountain region of Altai with intensity VI-VII MSK.
| | 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 41 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). | | Preliminary processing has been done with data from 20 stations, accurate processing - with data 33 stations. | | Figure 1 presents fragments of records from digital stations Borovoe (11,3 degrees), Arti (18,6 degrees), Yakutsk (25,9 degrees), Tiksi (28,6 degrees), Obninsk ( 31,0 degrees), Lovozero (31,4 degrees), Magadan (36,2 degrees). In parentheses the distance from an epicentre up to station is given. |
Figure 1
|
| | 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 |
11-33-26.70 |
49 |
87 |
33 |
33 |
7.30/10 | 6.40/8 | 8.5-9 | 66 | IPC GS RAS (accurate) | | 2 |
11-33-27.30 |
50 |
87 |
33 |
20 |
7.3/7 | 5.9/4 | 8.5 | 179 | IPC GS RAS (preliminary) | | 3 |
11-33-23.90 |
50 |
87 |
10 |
389 |
7.1 | 6.6 | | 76 | CSEM | | 4 |
11-33-25.53 |
49 |
87 |
18 |
149 |
7.5/105 | 6.4/77 | | 36 | NEIC | | 5 |
11-33-31.36 |
49 |
87 |
30 |
39 |
| 6.5/39 | | 254 | ORFEUS | | 6 |
11-33-19.0 |
49 |
88 |
|
|
7.5 | | | | ASRIPC (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 | | ORFEUS - Observatories and Research Facilities for EUropean Seismology | | ASRIPC - Regional Informational Processing Center of Altai-Saiyany Experimental-Methodical Seismological Expedition Geophysical Survey Siberian Branch Russian Academy of Sciences | | Epicenter | | According to the scheme of newest geo tectonic structures of Northern Eurasia (Grachev A.F., 2000) Altai earthquake of 2003 has happened in Altai-Sayan-Mongol orogenic area in it’s North-Western part. | | Aftershock | | The Altay earthquake on September, 27, 2003 is accompanied numerous aftershocks. For the period from September, 27 till October, 2, 2003 in Service of Alert Survey of the Russian Academy of Science are determined parameters 25 aftershocks. From them the strongest aftershock with magnitude M=7.0 has taken place on October, 1 at 01 o'clock 03 mines (GMT).
|
| 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 |
| 20031412 | 2003-09-27 13:03:10.0 | 49.97 | 87.94 | 33 | 9 | - | 4.3/ 5 | - | Kazakhstan-Xinjiang border reg. | | 20031413 | 2003-09-27 13:16:46.0 | 50.06 | 87.82 | 33 | 6 | - | 5.1/ 6 | 3.5-4 | Southwestern Siberia, Russia | | 20031414 | 2003-09-27 13:38:05.0 | 50.18 | 87.52 | 33 | 7 | - | 4.1/ 4 | - | Southwestern Siberia, Russia | | 20031415 | 2003-09-27 15:31:25.0 | 50.15 | 87.55 | 33 | 11 | - | 4.4/ 6 | - | Southwestern Siberia, Russia | | 20031416 | 2003-09-27 15:49:07.0 | 50.01 | 87.96 | 33 | 11 | - | 4.2/ 5 | - | Southwestern Siberia, Russia | | 20031418 | 2003-09-27 18:52:49.0 | 50.16 | 87.66 | 33 | 30 | 6.7/ 10 | 6.0/ 11 | 7.5-8 | Southwestern Siberia, Russia | | 20031419 | 2003-09-27 20:30:27.0 | 50.19 | 87.61 | 33 | 12 | - | 4.7/ 7 | 2.5-3 | Southwestern Siberia, Russia | | 20031428 | 2003-09-28 08:40:56.0 | 49.96 | 87.74 | 33 | 10 | 3.6/ 6 | 4.3/ 5 | 3 | Kazakhstan-Xinjiang border reg. | | 20031429 | 2003-09-28 11:09:08.0 | 50 | 88.08 | 33 | 7 | 3.5/ 2 | 3.9/ 2 | 2.5-3 | Russia-Mongolia border region | | 20031431 | 2003-09-28 15:03:39.0 | 50.16 | 87.66 | 33 | 10 | 3.5/ 3 | 4.3/ 5 | 2.5-3 | Southwestern Siberia, Russia | | 20031433 | 2003-09-28 19:33:40.0 | 49.97 | 87.66 | 33 | 8 | - | 4.1/ 4 | - | Kazakhstan-Xinjiang border reg. | | 20031434 | 2003-09-28 19:43:36.0 | 50.05 | 87.83 | 33 | 10 | 4.1/ 5 | 4.5/ 4 | 3.5-4 | Southwestern Siberia, Russia | | 20031440 | 2003-09-29 06:51:12.0 | 49.95 | 87.94 | 33 | 7 | 3.0/ 3 | 3.8/ 3 | - | Kazakhstan-Xinjiang border reg. | | 20031442 | 2003-09-29 09:27:04.0 | 49.95 | 87.49 | 33 | 8 | 3.3/ 4 | 4.1/ 4 | 2.5-3 | Kazakhstan-Xinjiang border reg. | | 20031444 | 2003-09-29 15:27:06.0 | 50.43 | 87.59 | 33 | 11 | 4.1/ 6 | 4.6/ 8 | 3.5-4 | Southwestern Siberia, Russia | | 20031447 | 2003-09-29 16:59:25.0 | 49.2 | 87.97 | 33 | 6 | 3.3/ 1 | 3.3/ 3 | 2.5-3 | Kazakhstan-Xinjiang border reg. | | 20031451 | 2003-09-30 08:27:09.0 | 50.27 | 88 | 33 | 8 | 3.9/ 4 | 4.5/ 4 | 3.5 | Southwestern Siberia, Russia | | 20031457 | 2003-10-01 01:03:27.0 | 50.21 | 87.61 | 33 | 33 | 7.0/ 13 | 6.2/ 13 | 8-8.5 | Southwestern Siberia, Russia | | 20031458 | 2003-10-01 02:38:21.0 | 50.15 | 87.6 | 33 | 8 | - | 4.4/ 4 | - | Southwestern Siberia, Russia | | 20031459 | 2003-10-01 03:58:46.0 | 50.11 | 87.68 | 33 | 15 | 4.5/ 3 | 4.5/ 6 | - | Southwestern Siberia, Russia | | 20031460 | 2003-10-01 05:44:07.0 | 50.34 | 87.55 | 33 | 11 | 3.9/ 4 | 4.6/ 6 | 3.5 | Southwestern Siberia, Russia | | 20031461 | 2003-10-01 08:09:09.0 | 49.93 | 87.38 | 33 | 5 | 3.6/ 3 | 4.1/ 2 | 3 | Kazakhstan-Xinjiang border reg. | | 20031463 | 2003-10-01 12:21:29.0 | 50.25 | 87.31 | 33 | 6 | 3.3/ 2 | 3.7/ 2 | 2.5-3 | Southwestern Siberia, Russia | | 20031469 | 2003-10-02 01:46:19.0 | 50.33 | 87.07 | 33 | 9 | - | 4.2/ 3 | - | Southwestern Siberia, Russia | | 20031470 | 2003-10-02 03:12:12.0 | 50.32 | 87.68 | 33 | 7 | 4.1/ 2 | 4.1/ 3 | 3.5-4 | Southwestern Siberia, Russia | | | Macroseismic manifestations | | The earthquake 27.09.2003 at 15:33 (Moscow time) has been felt on a vast territory of Russia (in Republics - Altai, Hakasia, Buriatia, Krasnadar region, in regions - Novosibirsk, Kemerovo) and in Kazakhstan. According to information from Civil Defense Ministry of Russia, RSC Altai-Sayan RIPC and seismic station "Alma-Ata" (Kazakhstan) this earthquake was felt in Aktash with intensity 6-7 MSK, Tashtagol - 6 MSK, Prokopievsk -5-6 MSK, Novosibirsk, Ust-Kamenogorsk, semipalatinsk - 4 MSK, Abakan - 3-4 MSK, Krasnoyarsk, Zaisan, Kemerovo - 3 MSK, Barnaul, Alma-Ata, Taldi-Kurgan, Astana - 2-3 MSK
Aftershock with magnitude М=6.7 was registered on 27.09.2003 at 10:52pm (Moscow) and it was felt in Abakan, Biysk with intensity 2-3 MSK, Novosibirsk - 2 MSK.
The strongest aftershock was registered on 01.10.2003 at 05:03(Moscow)with magnitude M=7.0 was felt in Aktash with intensity 6 MSK, Barnaul - 3-4 MSK, Novosibirsk, Omsk, Krasnoyarck, Kemerovo, Nizhnevartovsk - 2-3 MSK
| | Historical records | | Four strongest earthquakes with magnitudes 8 and more were registered on the territory of Altai-Sayan-Mongol orogenic area according to the Special catalogue (publisher Kondorskaya N.V., Ulomov V.I.). These are – Mongol earthquake 1761 with М=8.3, Cecerleg earthquake 1905 with М= 8.2, Mongol-Altai 1931 with М=8 and most southern in this zone - Gobi-Altai 1957 with М=8.1. Epicenters of these earthquakes in accordance with map (fig.2 ) are located significantly far to the south-east, approximately 500 km and more from Altai earthquake on September 27, 2003. Two minor earthquakes located in epicentral zone of reported here event are known: on September 14, 1923 with М=6.0 and on September 20, 1960 with М=5.1, macroseimic consequences from them are unknown. | 
Figure 2 |
| | Focal mechanism and seismic moment of the earthquake | | Focal mechanism solutions for the earthquake 27.09.2003 at 11:33 (Moscow) have been obtained in IPC GS RAS by signs of initial arrivals of p waves at 75 stations. At 48 of these stations they were registered as compression waves - sign "+", at 27 stations – as expansion waves (sign "-"). Elements of mechanism are presented in table 2. Here one can find solutions obtained by TMC method in different centers - NEIC and HARVARD. Figures 3-5 present graphical representation in stereographical projection for low hemisphere of focal mechanism. Solutions obtained in different centers are almost similar.
Reported earthquake has happened in conditions of both compression strengths oriented to the North and expansion strengths, oriented to the West-East. Both nodal planes are steep falling, NP1 plane is oriented to the North-West-South-East direction, NP2 plane – to the North-East-South-West. Trap down component prevails for both planes.
Averaged value of Мо determined in IPC GS RAS from Р-wave spectra at two seismic stations: "Obninsk" and "Kislovodsk" (delta 31 degrees), made 2.8* 10** 19 n*m. The value of moment magnitude from these data made Mw = 7.0.
From NEIC information the value of Мо made 1.0* 10** 20 n*m, the value of moment magnitude - Mw = 7.3.
From HARVARD information the value of Мо made 9.9* 10** 19 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 |
| 13 | 275 | 10 | 8 |
74 | 135 | 52 | 74 | 2 | 321 |
88 | 164 | IPC GS RAS | | 10 | 262 | 18 | 356 |
69 | 143 | 38 | 70 | -5 | 130 |
85 | -160 | NEIC | | 32 | 93 | 11 | 355 |
55 | 248 | 227 | 76 | 32 | 129 |
59 | 164 | 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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