Information message about the earthquake in Chechnia territury happened on January 30, 2002 | | On January 30, 2002 the earthquake with magnitude Mb=4.4 has happened in the central part of Chechen territory, its origin was located in the upper mantle of the Earth. | | Parameters of this earthquake have been determined in Alert Survey (AS) of Information-Processing Center (IPC) of Geophysical Service of RAS in Obninsk with station data obtained from digital and analog seismic stations of Russia, CIS countries and from abroad.
Alert message about this earthquake has been sent to the Ministry of Russian Federation dealing with civil defense, extraordinary situations and liquidation of natural disasters.
| | Processing of this event has been done with data from 16 stations: from 2 analog stations: Mahachkala, Piatigorsk, which are the nearest to hypocenter (delta 1,5o and 1,9o) and from 14 digital stations. Waveforms from 4 digital stations have been obtained and considered by IPC in a near to real time mode: Kislovodsk (Russia) - delta 2,2o, Garni (Armenia) - delta 3,7o, Obninsk (Russia) - delta 12,9o, Borovoe (Kazahstan) - delta 18,8o. For 3 stations the data have been obtained via e-mail from radio telemetering stations RSS at Caucasus Mineral Waters geodynamics test area (SHAR, NAGR, GUMR – delta from 2.2o to 2.5o) and one digital station in Makanchi, MKAR (Kazahstan); data from other stations and groups (FINES, NORES, GERES, BGCA, HFS, YKA) have been taken from Internet bulletins of international centers.
| | Rather sharp deep phases of sP and pP are seen in records from remote stations: Obninsk and Borovoe. They have been used to confirm origin place. Figure 1 shows both broadband (blue) and filtered in frequancy band 0.6-1.9 Hz (red) records for vertical channels of these stations.
Analysis of waveform picture for the earthquake on January 30, 2002 (fig. 2) with records from the nearest to KMD test site stations (delta from 150 to 250 km) in comparison with crust records from the earthquake on December 25, 2001 (fig.3) (see Information message on this event), which happened slightly to the North-West, also confirm significant depth of reported here event on January 30. Distinct and sharp arrival of both Р and S waves, significant fading of Р wave code at the moment of S wave arrival to the station and too weak surface waves – all this may be seen almost in all records from each station (except seismic station Gumbashi (GUMR), which is shown at the bottom of the figure, this station is most far located to the East from the origin place).
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Figure 1
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Figure 2
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Figure 3
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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 |
04-01-39.90 |
43 |
45 |
140 |
16 |
| 4.40/4 | | | IPC GS RAS | | 2 |
04-01-21.0 |
43 |
46 |
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4 |
| | | | NORSAR | | | IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences | | NORSAR - Norwegian Seismic Array | | Macroseismic manifestations | | At this moment no information has been obtained by IPC GS RAS about this earthquake. | | Historical records | | The earthquake on January 30, 2002 has happened in the valley of Terek river, in central part of Chechnia territory, this is 35 km to the North from Grozny city. This region is one of the few Caucasian regions with historically known origins at the depths from 50 to 125 km.
The topic of specific Caucasian zones with earthquakes origins in the upper mantle was often discussed in literature. After instrumental processing Dr.Lebedeva (1958) distinguished 6 earthquakes with origins below the Earth's crust for the period between 1911 and 1958. These earthquakes include one, which happened on 10.09.1954 at 19:21 with coordinates 43.2 N 45.4 E and depth 80 km. Dr.Shebalin (1961) and Dr. Tshakaya (1962) also mentioned availability of some specific Caucasian origins with focal depths in the upper mantle. Data for some of these origins later have been composed in the "New catalogue of the strong earthquakes on the territory of USSR, 1977", they were classified as crust events. Only one of the published in this catalogue events on 10.08.1912, which happened in the considered here region of the earthquake on January 30, 2002, had the depth of 50 km and magnitude 5.7.
Dr. Godzikovskaya (in 1988) drew attention of seismologists to the presence of zone with mantle earthquakes at the depths of 80-120 (100-140) km in Tersk-Sunzhensk flexure as a result of seismic survey at the station Beli Ugol (White Coal).
New signs of deep origins on Caucasus at Tersk-Sunzhensk flexure has appeared after additional analysis with available instrumental materials used in preparation of «Specialized catalogue of the earthquakes in Northern Eurasia» (ed. Dr.N.Kondorskaya, Dr. V.Ulomov, 1996). They include in particular the earthquake on 17.07.1976 at 01:39мин 43.16N 45.38N with depth 125 km, Ms= 4.3 and on 18.01.78 at 19:34мин 43.05N 45.74E with depth 94 km, Ms=3.4.
Within the whole period of surveillance, starting from the beginning of the century and up now, 22 earthquakes have been detected in zone 42.5N - 44 N, 44E - 46E with origin depths 50 km and more. Their locations are shown on the map, which depicts also the breaks in accordance with Dr.S.Rogozhin.
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Figure 4 |
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