Information message about the earthquake in Caspian sea on November 25, 2000 |
| On November 25, 2000 two strong earthquakes have happened in Caspian sea near Apsheron peninsula (Azerbaijan), the first event - at 21:09 Moscow time (18:09 GMT) and the second one in 1 minute 37 seconds later. These earthquakes have been felt on a vast territory along the Caspian sea coast. |
| 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 41 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Improved calculation has been done for the first event with seismic waves arrivals obtained from 38 stations. In addition the data have been received from other stations of Russia, including Dagestan experimental expedition of Russia as well as the Republican Center of seismic service of Azerbaijani Academy of Sciences, National seismic protection service of Armenia, Regional seismological center of Turkmenistan and data from some stations of Ukraine, Uzbekistan, Moldavia, Byelorussia.
For the second event more accurate calculation will be done later because of the complexity of wave picture (superposition and interference of waveforms).
|
| Figures 1-2 present records from digital stations, which have been received by IPC in a close to real time mode.
|
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: |
| Note: (1) - First earthquake,
(2) - Second earthquake. |
| 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 |
(2)18-10-50.5 |
40 |
50 |
33 |
9 |
| 6.0/6 | 6 | | IPC GS RAS (preliminary) | | 2 |
(1)18-09-.0 |
41 |
49 |
|
|
5.5 | | | | IPC GS RAS (RCSS AS Azerbaijan) | | 3 |
(1)18-09-13.5 |
40 |
50 |
33 |
10 |
6.6/5 | 6.1/1 | 7.5 | | IPC GS RAS | | 4 |
(1)18-09-09.90 |
40 |
50 |
50 |
38 |
6.20/11 | 5.80/6 | 6.5-7 | | IPC GS RAS (improved) | | 5 |
(1)18-09-01.1 |
39 |
50 |
33 |
94 |
| 5.6-6.1 | | | CSEM | | 6 |
(2)18-10-45.1 |
40 |
50 |
10 |
134 |
6.3/55 | 6.2/28 | | | NEIC | | 7 |
(1)18-09-06.0 |
40 |
50 |
10 |
59 |
| 5.9/52 | | | NEIC | | 8 |
(1)18-09-07.6 |
41 |
49 |
-10 |
|
| | | | DRIPC | | 9 |
(2)18-10-56.8 |
40 |
50 |
97 |
17 |
| 5.8 | | | IDC | | 10 |
(1)18-09-07.6 |
40 |
49 |
9 |
15 |
| 5.6 | | | IDC | |
| 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 |
| DRIPC - Regional Informational Processing Center of Dagestan Experimental-Methodical Seismological Department Geophysical Survey Russian Academy of Sciences |
| IDC - International Data Senter, Austriya, Viena |
| Aftershock |
| The earthquake on November 25 has been accompanied with numerous aftershocks. Parameters for six of them having magnitudes more than 3.5 are presented on the "Alert messages" page of http://www.ceme.gsras.ru server under reference numbers 1484, 1485, 1487, 1488, 1489, 1491. |
| Macroseismic manifestations |
| These earthquakes have been felt on the vast territory of Caspian coast, with the strongest intensity – in cities Baku and Sumgait - VI MSK in twelve steps scale MSK 64. It was also felt (from messages of regional centers of Azerbaijan, Turkmenistan and Dagestan) in Izerbash (Dagestan) - V MSK, Beckdash (Turkmenistan) IV-V MSK and in Dagestan: Mahachkala, Srgokala – IV MSK, Derbent – III-IV , Hasaviurt – III, Kumuh – II-III, Buinaksk – II MSK.
From ITAR TASS data by November 26 at 17-00 local time 26 people have been dead from the obtained injuries and stress, capital hospitals received 298 injured persons.
The earthquakes caused damage to thousands of objects in Baku including living houses. The most damaged objects were old buildings, some of them represent architectural value.
|
| Historical records |
These earthquakes have happened in the water space of Caspian sea adjacent to Apsheron seismic intensive zone ["Seismic zoning of the USSR ", M. Science, 1968, pp. 229]. From data of "Specialized catalogue" (red. Kondorskaya N.V., Ulomov V.I.) in the previous hundred years some strong earthquakes were registered in the region of Caspian sea, some with intensity in hypocenter equal to 6 and more MSK (see table 3). As it is seen from table 3, most of the strongest earthquakes happened in North Apsheron water place of Caspian sea. Their intensities in hypocenter (earthquakes of 1842 1963, 1986 and 1989) reached VIII MSK. They were felt on the most part of Apsheron peninsula with intensities of up to VII MSK.
Origin place of the earthquake on November 25, 2000 is located on fig. 3 in the south part of Apsheron zone and is associated with Apsheron-Chelekensk boundary. Detailed description of this zone seismic tectonics is given in almanac " Earthquakes in the USSR in 1986 " in accordance with the Caspian earthquake on March 6, 1986, which had magnitude 6.1.
| Date | Time | Coordinates | Depth | Ms | Io |
| year | month | day | hour | min | sec | North
Latitude
(degr) | East
Longitude
(degr) | km | | balls | | 1842 | 1 | 2 | 22 | | | 40.5 | 50. | 3 | 4.3 | 8 | | 1911 | 6 | 7 | 23 | 58 | 48. | 41.0 | 50.5 | 52 | 6.4 | 6-7 | | 1929 | 12 | 24 | 22 | 12 | 14. | 41. | 49.5 | 15 | 4.7 | 6 | | 1931 | 7 | 25 | 7 | 39 | 10. | 41.4 | 49.5 | 16 | 4.8 | 6 | | 1931 | 10 | 20 | 15 | 58 | 32. | 41.7 | 51.1 | 110 | 6.2* | 7 | | 1938 | 9 | 6 | 13 | 28 | 20. | 41. | 50. | 22 | 5.0 | 6 | | 1946 | 3 | 5 | 4 | 45 | 7. | 39.6 | 49.3 | 11 | 4.8 | 7 | | 1951 | 1 | 16 | 17 | 53 | 53. | 39.1 | 49.6 | 25 | 4.9 | 6 | | 1961 | 6 | 9 | 9 | 36 | 48. | 40.8 | 50.6 | 14 | 4.8 | 6 | | 1961 | 9 | 18 | 11 | 1 | 4. | 41.1 | 50.2 | 64 | 6.0 | 7 | | 1961 | 9 | 19 | 20 | 5 | 22. | 40.9 | 49.9 | 60 | 4.4 | 5-6 | | 1961 | 12 | 17 | 14 | 28 | 40. | 40.5 | 50. | 6 | 4.2 | 7 | | 1961 | 12 | 17 | 14 | 33 | 45. | 40.5 | 50. | 3 | 4.1 | 7 | | 1962 | 3 | 26 | 16 | 39 | 43. | 41.1 | 49.3 | 6 | 4.4 | 7 | | 1962 | 7 | 1 | 11 | 46 | 30. | 40.7 | 49.6 | 13 | 4.5 | 6 | | 1963 | 1 | 27 | 19 | 35 | 15. | 41.08 | 49.84 | 55 | 6.2 | 7-8 | | 1963 | 1 | 31 | 17 | 6 | 2. | 40.8 | 49.8 | 5 | 4.5 | 5-6 | | 1968 | 5 | 11 | 12 | 12 | 41. | 41.1 | 49.9 | 15 | 4.5 | 6 | | 1969 | 11 | 4 | 20 | 17 | 49. | 40.31 | 50.28 | 22 | 4.4 | 6 | | 1972 | 6 | 14 | 0 | 49 | 54. | 40.26 | 51.84 | 27 | 4.1 | 6 | | 1986 | 3 | 6 | 0 | 5 | 38.2 | 40.06 | 51.63 | 29 | 6.1 | 7-8 | | 1989 | 8 | 24 | 18 | 55 | 23.6 | 41.64 | 49.09 | 55 | 3.8 | 6 | | 1989 | 9 | 16 | 2 | 5 | 7.0 | 40.34 | 51.60 | 29 | 6.3 | 7-8 | | 1989 | 9 | 17 | 0 | 53 | 38.8 | 40.15 | 51.82 | 32 |
6.2 | 7 |
|
Figure 3 |
|
| Focal mechanism and seismic moment of the earthquake |
| Table 4 and figure 4 keep solution of origin mechanism for the earthquake on November 25 at 18:09GMT, which was obtained in Harvard, USA - (3) and Potsdam, Germany - (2) from CMT method (centroid of moment tensor). Here one can find the solution (1) obtained in IPC GS RAS with the use of first signs of longitudinal wave arrivals. Data about the signs (17 signs "plus" and 23 signs "minus") have been obtained at 40 stations located in the interval of hypocenter distances of 0.56-73.6 degrees.
Solutions of origin mechanisms obtained by different methods and authors have the same features. According to all solutions the motion in the origin place is a thrust (сброс). Besides that one of the nodal planes has the same orientation (from the north-west to the south-east) with close falling angles (59-67 degrees). The spread direction of this plane corresponds to the spread of Apsheron-Chelekensk and other big depth ruptures of Apsheron - Pribalhansk motion system.
Seismic moment Мо of the earthquake has been determined from Р-waves spectra registered by IRIS digital system at TLY station (Talaya, Irkutsk region), which is located at 37 degrees distance from the earthquake hypocenter. The value of Мо made 1.0 Е +19 n*m. Moment magnitude value has been determined as Мw=6.6. The value of Mw determined by CMT method made Mw=6.4 from Harvard data and Mw=6.3 from Potsdam data.
|
| 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 |
| 10 | 53 | 39 | 315 |
49 | 155 | 180 | 49 | -33 | 293 |
66 | -134 | IPC GS RAS | | 2 | 86 | 40 | 354 |
50 | 179 | 209 | 55 | -39 | 324 |
59 | -138 | IPC GS RAS | | 22 | 32 | 6 | 125 |
67 | 230 | 110 | 24 | -106 | 308 |
67 | -83 | HARVARD | |
| IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences |
| IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences |
| HARVARD - Harvard Geophysical Center (USA) |
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