Information message about the earthquake in Chechen Republic on October 12, 2006 |
| The earthquake with magnitude M=5.1 has happened on October 12 at 21:16 GMT (October 13 1:16am Moscow time) on the territory of Chechen Republic. Epicenter of the earthquake was located at 50 km to the North from capital Grozny. The depth of this - 145 km.
|
| 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 43 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 15 stations, accurate processing - with data 29 stations. |
| Fig. 1 presents fragments of records for this earthquake obtained from digital stations Kuba-Taba (∆ 1.7º), Kislovodsk (∆ 2.2º), Shatzhatmas (∆ 2.2º), Garni (∆ 3.8º). Fig. 2 presents fragments of records for this earthquake obtained from digital stations Obninsk (∆ 12.8º), Arti (∆ 15.1º), Borovoe (∆ 18.7º), Ala Archa (∆ 21º). As one can see from fig. 3, for the stations with epicentral distances 49º-58º it is clearly determined depth phase pP. |
Figure 1
| 
Figure 2
| 
Figure 3
|
|
| 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 |
21-16-50.3 |
43.76 |
45.68 |
145 |
29 |
| 5.1/7 | | 109 | IPC GS RAS (Accurate) | | 2 |
21-16-50.4 |
43.77 |
45.65 |
145 |
15 |
| 5.1/5 | | 109 | IPC GS RAS (Preliminary) | | 3 |
21-16-49.3 |
43.759 |
45.741 |
135.8 |
185 |
| 4.8 | | 104 | CSEM | | 4 |
21-16-45.4 |
42.942 |
45.37 |
17 |
5 |
К11.7 | | | | DRIPC | | 5 |
21-16-53.37 |
43.526 |
45.628 |
10 |
4 |
Ml4.5 | | | | UNSSPG | |
| IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences |
| CSEM - European - Mediterranean seismological center |
| DRIPC - Regional Informational Processing Center of Dagestan Experimental-Methodical Seismological Department Geophysical Survey Russian Academy of Sciences |
| UNSSPG - United National Survey for Seismic Protection , Georgia |
| Historical records |
| A few earthquakes interpreted as tectonic earthquakes with the origins in upper mantle have been registered in the period since 2000 up now on the territory of Tersk -Sunjinsk flexure. The most significant of them have happened on January 30, 2002 4h01m with Кр=11.1, January 30 2002 6h43m with Кр=9.6, July 6, 2004 with 15h 15m with Кр=11.5, July 23 2004 at 23h 03m with Кр=10.2, November 18 2005 at 21h 24m with Кр=10.4 and August 17, 2006 at 05h43m with Кр=10.3.
The issue of existence in Caucasus some separate zones with origins in the upper mantle was discussed in literature many times [1, 2, 3]. Dr. Lebedeva T.M. (1958) determined 6 earthquakes with origins below the crust with use of instrumental data for the period since 1911 till 1958, including the earthquake 10.09.1954 at 19:21 with coordinates 43.2 N 45.4 E and depth 80 km in Sunzhinsk frlexure. Dr. Shabalin N.V.(1961) and Tsakhaya A.D. (1962) also mentioned about existence of separate origins with focal depths in upper mantle in Caucasus. However that data for some of these origins later was reprocessed and they were included in «New Catalogue of the strong earthquakes on the territory of USSR, 1977» as crust events. Only one origin 10.08.1912 from those published in this catalogue had the depthу 50 km and magnitude 5.7. Dr. Godzikovskaya A.A. [3] supposed the existence of zone with mantle earthquakes at the depths 80-120 km (100-140) in the area of Tersk-Sunghinsk flexure after analysis of survey information obtained at seismic station Beliy Ugol (White Coal).
After additional analysis of available instrumental data used for preparation of «Specialized catalogue of the earthquakes of Northern Eurasia » (ed. Dr. Kondorskaya N.V., Dr. Ulomov V.I., 1996) the new information appeared about the deep origins in Caucasus, in the area of Tersk-Sunzhinsk flexure. These origins include the earthquakes 17.07.1976 01:39 43.16N 45.38N with depth 125 km, Ms= 4.3 and 18.01.78 at 19:3443.05N 45.74E with depth 94 km, Ms=3.4.
The nature of these events probably is determined by seismic zone, which spreads from Caspian Sea to the North-West and has general Caucasian direction of propagation.
1 Lebedeva T.M. Earthquakes of Caucasus with origins under the crust. //Тр.ИГ АН GrSSR.1958.V.17.pp.139-159
2 Tsakhaya A.D. On the deep Caucasian earthquakes. //Izv. AS USSR. Ser. geoph..1962.№5. pp. 577-584.
3. Godzikovskaya A.A. Mantle earthquakes of Caucasus in the region of Tersk-Sunzhensk flexure.. //Izv. AS USSR. Physics of the Earth..1988.№7. pp. 102-106.
|
