Information message about sensitive earthquake in Tajikistan on May 12, 2012 |
| The sensitive earthquake with M=5.8 has occurred in Tajikistan on May 12, 2012 at 23:28 GMT (May 13, 03:28 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 11 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 59 stations, accurate processing - with data 69 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Ala-Archa (∆ 5º), Kurchatov (∆ 13.3º), Borovoe (∆ 14.3º), Arti (∆ 19.4º), Garni (∆ 19.9º). Fig. 2 presents fragments of records obtained from digital stations Talaya (∆ 26.5º), Obninsk (∆ 28º), Ulaanbaatar (∆ 28º), Yakutsk (∆ 42.4º), Tiksi (∆ 43.9º).
|
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 |
23-28-41.6 |
38.71 |
70.38 |
10 |
69 |
5.8/39 | 6/45 | 8-8.5 | 56 | IPC GS RAS (Accurate) | | 2 |
23-28-41.6 |
38.7 |
70.36 |
10 |
59 |
5.7/35 | 6/37 | 8 | 56 | IPC GS RAS (Preliminary) | | 3 |
23-28-42.8 |
38.66 |
70.42 |
4 |
862 |
Mw 5.7 | | | 34 | CSEM | | 4 |
23-28-43.8 |
38.66 |
70.41 |
10 |
338 |
Mw 5.7 | 6.0/197 | | 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 on the territory of Tajikistan at the depth of 10 km, 100 km N-E of Kulob, 126 km E of Dushanbe and 165 km S-E of Leninabad. |
Figure 3 |
|
| Macroseismic manifestations |
| ITAR-TASS reported about one killed person and dozens of damaged houses including farm facilities in Garm region of Tajikistan. This information was obtained by ITARR-TASS correspondent from regional administration. The killed person was from Samsalik settlement which is located close to the epicenter of this earthquake which invoked landslip. Sheep and cow herds and dozens of cars and trucks occurred under the layer of soil. "These are only preliminary results based on operative information obtained from managers of farm facilities, the final scale of disaster may be much more significant after detailed analysis to be made by specially organized commission ", - says representative of Garm administration.
Fig. 4 was obtained from USGS NEIC , presents the map with intensities based on messages from 20 respondents living in 2 places. This earthquake was felt in Dushanbe and Toshkent with intensity 3. |
Figure 4 |
|
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism of the earthquake on May 12, 2012 at 23:28 was computed at IPC GS RAS using signs of P-wave first arrivals at 71 stations, including 51 stations which registered compression waves (“plus” signs) and 20 stations with registered extension waves (“minus” signs). These stations are distributed uniformly as regards to their azimuth to the earthquake epicenter and are located at 4–94º distances from it. The focal mechanism in stereographic projection at the lower hemisphere is presented at Fig.5, its elements are given in Tab.2. Tab.2 and Fig.6,7 also present focal mechanism solutions obtained in USGS NEIC with Centroid Moment Solution technique and in Quick CMT Catalog, USA, with CMT technique. All solutions of the centers listed in Tab.2 are identical. The NP1 nodal plane is steeply dipping (DP=70-83º) and has meridional strike (STK=181-189º). The NP2 nodal plane has low-angle dipping (DP=8-36º) and north (STK=5º according to IPC GS RAS) or north-east (STK=5-61º according to USGS NEIC, Quick CMT) strike. The earthquake occurred under the action of prevailing horizontal (Pl=19º-38º) compressive stresses oriented to the west. Tensile stresses are rather vertical (Pl=55º-64º) and oriented in an easterly direction (SE, E, NE according to IPC GS RAS, NEIC and Quick CMT solutions respectively). According to the IPC GS RAS and USGS NEIC, slip type at the source is a reverse fault for NP1 and a thrust for NP2. According to Quick CMT, a reverse fault with left-lateral component at NP1, and overthrust with right-lateral component at NP2 nodal plane have occurred. The seismic moment of the earthquake on May 12, 2012 at 23:28 obtained in the IPC GS RAS from the P-wave spectrum at "Obninsk» station (Δ 27.96º) is Mo=1.1*10**18 N*m. The average value of moment magnitude Mw calculated by the Kanamori formula is Mw=6.0. According to the USGS NEIC, Mo=9.5*10**17 N*m, Mw=5.9; according to Quick CMT, Mo=5.32*10**17 N*m, Mw=5.8. |
| 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 |
| 64 | 101 | 26 | 278 |
1 | 8 | 189 | 71 | 91 | 5 |
19 | 86 | IPC GS RAS | | 52 | 92 | 38 | 279 |
3 | 186 | 186 | 83 | 87 | 31 |
8 | 115 | NEIC | | 55 | 53 | 19 | 294 |
28 | 193 | 181 | 70 | 60 | 61 |
36 | 144 | 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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