Information message about the strong earthquake in the South-East of Iran, December 20, 2010 |
| The strong earthquake with М=6.6 has occurred on December 20, 2010 at 18:41 GMT (21:41 Moscow time) in the South-East of Iran. |
| 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 45 stations, accurate processing - with data 62 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Garni (∆ 16.7º), Ala Archa (∆ 18.8º), Neitrino(∆ 19.9º), Kislovodsk (∆ 20.5º), Isparta (∆ 25.8º). Fig. 2 presents fragments of records obtained from digital stations Arti (∆ 28º), Obninsk (∆ 31.4º), Kiev (∆ 31.8º), Krasnoyarsk (∆ 36.5º), Ulaanbaatar (∆ 41.6º). |
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 |
18-41-57.2 |
28.38 |
59.28 |
10 |
62 |
6.6/32 | 6.2/34 | 9-9.5 | 44 | IPC GS RAS (Accurate) | | 2 |
18-41-56.9 |
28.36 |
59.3 |
10 |
45 |
6.6/21 | 6.2/28 | 9-9.5 | 101 | IPC GS RAS (Preliminary) | | 3 |
18-41-59.0 |
28.49 |
59.25 |
4 |
507 |
Mw 6.5 | | | 26 | CSEM | | 4 |
18-41-59.9 |
28.491 |
59.117 |
11.8 |
244 |
Mw 6.5 | 6.1/157 | | 25 | NEIC (Accurate) | | 5 |
18-41-59.9 |
28.439 |
59.098 |
12.4 |
107 |
Mw 6.3 | 6.1/65 | | | NEIC (Preliminary) | | 6 |
18-42-02.5 |
28.53 |
59.13 |
5 |
28 |
ML6.5 | | | | IGUT | |
| 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 |
| IGUT - Institute of Geophysics, University of Tehran |
| Epicenter |
| Fig. 3 presents with red star epicenter of this earthquake, which origin was located at the South-East of Iran , at the depth of 10 km, in 200 km S-W from Zahedan, Iran, in 320 km E-N-E from Bandar E-Abbas, Iran, and in 305 km S-E from Kerman, Iran. |
Figure 3 |
|
| Aftershock |
| GS RAS registered 2 aftershocks: with М=5.0 in 3,5 hours and with М=4.4 in 17,5 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 |
| 20104164 | 2010-12-20 22:12:56.0 | 28.13 | 59.3 | 10 | 15 | - | 5.0/ 12 | 5-5.5 | Southern Iran | | 20104174 | 2010-12-21 12:14:16.0 | 28.25 | 58.95 | 10 | 15 | - | 4.4/ 12 | 4 | Southern Iran | |
| Macroseismic manifestations |
| In accordance with data from RIA-Novosti seven persons became the victims of this earthquake and hundreds are injured. A few hundred people were occurred under the debris. State TV channels report, that the disaster destroyed at least three settlements, where the houses were built from clay. |
| Historical records |
| Epicenter of this earthquake was located in 120 km S-E from epicenter of destructive earthquake which occurred on December 26, 2003., which destroyed 90% of ancient Iranian city Bum and killed 31 thousands of people. |
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solution of this earthquake which happened on December 20, 2010 at 18:41 GMT was calculated in IPC GS RAS with first signs of P-wave arrivals at 70 stations, including 42 stations which registered the waves of compression (plus signs), and 28 stations which registered the waves of expansion (minus signs). These stations are located with interval of epicenter distances of 4º-93º degrees between them with rather uniform dispersion along the azimuth. Focal mechanism solution is presented at fig 4 in the form of stereographic projection at the lower hemisphere, element of this solution are presented in table 2. Table 2 and figures 5, 6 also present focal mechanism solutions obtained with CMT method in NEIC USA, USGS and Global CMT Catalog, USA. All solutions obtained with different methods are similar. The earthquake has occurred under the action of almost equal compression and expansion forces, the type of motion – shifts with available vertical component (uplift).
Direction of propagation of nodal plane NP1 in all cases – N-E, and for NP2– N-W. However in USGS calculation NP2 lays more flat with the same azimuth of propagation(DP=33º) if compared with solutions which are based on Р-waves and СМТ (DP=70-90º).
Seismic moment of this earthquake which occurred on December 20, 2010 was obtained in IPC GS RAS with Р-wave spectra obtained at two stations: «Arti» (∆ 28.05º) and "Obninsk" (∆ 31.37º), it makes Мо=5.3*10**18 n*m. Averaged value of moment magnitude Mw, calculated with Kanamori formula, makes Mw=6.4.
The value of seismic moment Мо in accordance with USGS makes 1.2*10**19 n*m, the value of moment magnitude Mw=6.7. In accordance with data from Global CMT Catalog - Мо=8.38*10**18 n*m and Mw=6.5.
|
| 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 |
| 23 | 346 | 5 | 78 |
67 | 180 | 30 | 78 | 160 | 124 |
70 | 13 | IPC GS RAS | | 35 | 163 | 38 | 286 |
33 | 46 | 45 | 88 | -123 | 313 |
33 | -3 | NEIC | | 4 | 351 | 4 | 261 |
85 | 128 | 36 | 85 | 180 | 126 |
90 | 5 | 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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