Information message about the earthquake happened in the South-Western part of Sakhalin island | | The sensitive earthquake with magnitude М=4.6 has happened in the South-Western part of Sakhalin island on May 30, 2004 at 02:52am GMT, it was felt in settlement Kostromskoe with intensity 6 MSK (in the coastal part of Sakhalin island from the side of Tatar channel). | | Figure 1 presents three component record of this earthquake registered at seismic station South-Sakhalinsk (YSS), located at the distance of nearly 70 km. from the epicenter. |
Figure 1
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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 |
02-52-10.20 |
47.39 |
142.13 |
10 |
21 |
4.60/7 | 4.90/7 | 6-6.5 | | IPC GS RAS (предварительный) | | 2 |
.0 |
|
|
|
|
| | | | IPC GS RAS | | 3 |
.0 |
|
|
|
|
| | | | IPC GS RAS | | 4 |
.0 |
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| | | | IPC GS RAS | | | IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences | | Epicenter | | Epicenter of this earthquake was located in the South-Western part of Sakhalin island. In accordance with information represented on Web site of Sakhalin Experimental Methodical Expedition of RAN "On seismicity of Sakhalin and Kuril Islands in 2004 - 2005. Expert estimation" (author Mr. I.N. Tihonov – scientist of Institute of sea geology and geophysics of Far East) the zone of this earthquake belongs to the tectonical area of South Sakhalin. Scientists have found here two major types of deep ruptures, which cause the strong earthquakes. This first system (Western-Sakhalin) is most powerful and stretches under the bottom of Tatar channel along the Western coast to the neck Poyasok (at 48 degrees of Northern latitude), then it joins with ruptures of the Middle Sakhalin. It is this area, where the strongest earthquake for the last 100 years with intensity M=7,5 and origin’s depth 18 km. has happened on September 5, 1971 close to Moneron island. Location of Moneron’s earthquake epicenter is shown on figure 2.
Nowadays, from the point of scientists, seismic mode at Moneron part of the first zone of ruptures is in calm stage of development. Taking in account the fact, that such events repeat very seldom (hundreds of years) it is possible to expect that background activity will stay the same here for the nearest years to come. However, to the North from Holms to Tomari, where reported here event has happened on May 30, 2004, probability of the strong earthquake (opinion of the authors of expert estimation) in the nearest years is quite high, as there were no strong earthquakes here in the last 100 years, so there was no significant relaxation of the strengths.
The second system of ruptures (Central-Sakhalin) stretches from the South to the North in the following manner: to the West from settlements Kirillovo and Taranai on Krilion peninsular, to the West from regional center, then along the Eastern coast of the island to the town of Poronaisk and then to the settlement Onori and town Aleksandrovsk-Skhalinsk. In this area of ruptures at the South of Sakhalin there were two strong earthquakes in the last 100 years: Anivskoe 2.02.1951 (М = 5,5; Н » 10 km) and Takoiskoe 1.09.2001 (М = 5,6; Н » 10 km).
Takoisk earthquake happened in Dolinsk region and was the strongest one in the bunch of strikes for the second system of ruptures from settlement Kluchi to Uglezavodsk town. Such bunches of earthquakes were observed here regularly with interval of 13 years. Takoisk bunch is also shown on the figure (fig.2)
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Figure 2 |
| | Macroseismic manifestations | | This earthquake was felt in settlements of the coastal part of Western part of Sakhalin: in Kostromskoe with intensity 6 MSK, in South Sakhalinsk - 4 MSK, Holmsk - 3 MSK and on Kuril islands in South Kurilsk with intensity 3 MSK. |
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