Information message on the earthquake in South Kurils region on January 28, 2000 |
| On January 28, 2000 at 5pm Moscow time (2pm GMT) the strong earthquake (with intensity 5-6MSK) happened in the south area of Kurils islands. |
| 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 39 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 19 stations, accurate processing - with data 33 stations. |
| Figures 1-2 present the records from digital stations, which were obtained by IPC in a close to real time mode. |
Figure 1
| 
Figure 2
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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 |
14-21-02.90 |
43 |
146 |
33 |
19 |
7.10/12 | 5.30/2 | 8-8.5 | | IPC GS RAS (initial) | | 2 |
14-21-03.5 |
43 |
146 |
33 |
33 |
7.1/17 | | 8-8.5 | | IPC GS RAS (improved) | | 3 |
14-21-10.3 |
43 |
147 |
50 |
|
6.9 | | | | IPC GS RAS (Sahalin EMSP GS RAS) | | 4 |
14-21-00.0 |
43 |
146 |
10 |
209 |
| 6.4-7.3 | | | CSEM | | 5 |
14-21-04.0 |
43 |
146 |
33 |
141 |
| | | | NEIC | | 6 |
14-21-03.5 |
43 |
146 |
20 |
25 |
| 6.2 | | | pIDC | |
| 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 |
| pIDC - Prototype International Data Center |
| Epicenter |
| Hypocenter of this earthquake was located in the Pacific Ocean's region of southern Kurils islands (80km south east from Shikotan island). According to data of Sahalin's EMSP GS RAS the earthquake was felt in Russia in the following places: Malokurilsk (Shikotan island) – intensity 6 MSK, South Kurilsk (Kunashir island) - intensity 5-6 MSK, Kurilsk (Iturup island) - intensity 5 MSK. From NEIC data it was also felt in Japanese islands: Hokkaido and northern Honshu. Location of hypocenter is shown on the map (fig.3).
|
Figure 3 |
|
| Macroseismic manifestations |
| From ITAR TASS information on January 29, 2000 this earthquake damaged some buildings and constructions on Kunashir island. This fact was told to correspondent of ITAR TASS in Head office of Civil Defense and Natural Disasters ministry branch of Sahalin region. In South-Kurilsk place some parts of communication lines have been broken. Regional specialists of specified above ministry and communication lines specialists were sent to liquidate the consequences. The victims and significant distractions were not noticed. |
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism of the earthquake 28.01.2000 was calculated in IPC GS RAS from first signs of Р-wave entrance at 31 stations, which are located in the interval of hypocentral distances 4.8-81.3 degrees with their rather uniform distribution between azimuths from 7 to 344 degrees. At first signs of motion 26 stations recorded he wave of compression (character "plus"), while 5 stations registered the wave of expand (character "minus"). Positions of nodal planes in projection of lower hemisphere are presented on figure 4 and in table 3.
Focal mechanism is characterized by thrust along both nodal planes. One of them having steeper depth (angle to horizon equal to 67 degr.) is oriented to the north-east direction, which corresponds with spread direction of Kurils ridge. Another plane has north-west direction and is inclined to horizon at a smaller angle (for this plane the angle of incidence makes 51 degrees). Axis of compression is almost horizontal, oriented to the east. Axis of stretching has northern orientation (almost along meridian) and is inclined to horizon at angle of 46 degrees.
Below one can see solution, obtained in Harvard center (USA) by method of moment's tensor of centroid. Both solutions are close to each other.
Seismic moment Мо of the earthquake has been determined in IPC GS RAS from spectra of P-waves, registered at 4 seismic stations: Talaya(TLY), Arti (ARU), Obninsk (OBN), Kislovodsk (KIV), which are located at hypocentral distances from 30 to 70 degrees. The values of seismic moment made Mo= 0.4 E 19 n* m, and moment magnitude Mw=6.3. From data of Harvard center they made Mo=2.0 E 19 n* m and Mw=6.8.
|
| 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 |
| 341 | 46 | 81 | 9 |
180 | 42 | 133 | 51 | 30 | 23 |
67 | 137 | IPC GS RAS | | 6 | 38 | 119 | 26 |
234 | 40 | 158 | 41 | 11 | 59 |
83 | 13 | HARVARD | |
| IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences |
| HARVARD - Harvard Geophysical Center (USA) |
Figure 4 |
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