Information message about the earthquake in the South-East of Iran on December 26, 2003 | | Destructive earthquake with magnitude М=6.8 has happened on December 26, 2003 in the South-East of Iran at 04:56am Moscow time (01:56 GMT). | | 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 54 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). | | Preliminary processing has been done with data from 26 stations, accurate processing - with data 33 stations. | | На рис. 1 представлены фрагменты записей цифровых станций: Кисловодск (19,43 градуса), Боровое (25,53 градуса), Арти (27,35 градуса),Обнинск (30,38 градуса), Пулково (36,11 градуса), Ловозеро (41,34 градуса) - в скобках указаны расстояния от эпицентра до станции. На рис. 2 представлены фрагменты записей цифровых станций: Улан-Батор (41,73 градуса), Якутск (56,08 градуса), Южно-Сахалинск (65,77 градуса), Магадан (66,60 градуса), Билибино (69,78 градуса), Петропавловск (73,11 градуса) - в скобках также указаны расстояния от эпицентра до станции. |
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 |
01-56-53.40 |
29.1 |
58.38 |
10 |
30 |
6.80/17 | 6.10/12 | 9.5-10 | | IPC GS RAS (предварительный) | | 2 |
.0 |
|
|
|
|
| | | | IPC GS RAS | | 3 |
.0 |
|
|
|
|
| | | | IPC GS RAS | | 4 |
.0 |
|
|
|
|
| | | | IPC GS RAS | | 5 |
.0 |
|
|
|
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| | | | IPC GS RAS | | | IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences | | Epicenter | | This earthquke has happened in the South-East of Iran. It's epicenter was located in the area of regional center Bam of Iranian province Kerman. Ancient Iranian town Bam with population of 100 thousands people is in 180 km to the South-East from Kerman city. Bam town has destructions of almost 90 percents. Iranian authorities published the number of killed - 30 thousands people (from information of ITAR-TASS on December 28, 2003). | 
Figure 3 |
| | Macroseismic manifestations | | Focal mechanizm solutions of the origin for this earthquake have been obtained at 01:56 in IPC GS RAS from the first arrivals of P-waves at 54 stations. 34 of these stations have registered waves of compression - symbol "+", 20 stations - waves of expansion (symbol "-"). Table 2 presents elements of focal mechanizm in accordance with data from IPC GS RAS, NEIC and HARVARD. Figures 4-6 demonstrate graphical presentation of stereographic projection for the lower hemisphere of phocal mechanizm. Solutions obtained in different centers by different methods are close to each other. Investigated earthquake has happened in conditions of both compression strengths oriented to the North-East-South-West direction, and expansion strengths oriented to the North-West-South-East. Both nodal planes have steep fall, NP1 plane has latitudinal spread direction, NP2 plane has meridional spread direction. Shift component prevails in motion along both planes. Averaged value of seismic moment Мо determined in IPC GS RAS from Р-wave spectra at seismic station "Obninsk" (delta 30 degrees) made 2.7* 10** 18 n*m. Moment magnitude from these data made Mw = 6.3. Seismic moment value Мо from NEIC made 6.6* 10** 18 n*m, moment magnitude - Mw = 6.5. Seismic moment value Мо from Harvard made 8.8* 10** 18 n*m, moment magnitude - Mw = 6.6. | | Historical records | | This earthquake has happened in seismic active region. This fact is confirmed by the map obtained from NIEC site (http://neic.usgs.gov/neis/world/iran/). Iranian plateau with active ruptures is characterized by numerous catastrophic earthquakes, which killed at least 126000 people in the last century. The strongest of these earthquakes have happened on September 16, 1978 with М=7.8; on June 20, 1990 with М=7.4. |
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