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Information message about sensitive earthquake in Kamchatka on June 10, 2004.

On June 10, 2004 at 15:19 GMT the strong earthquake has happened in the Eastern part of Kamchatka peninsula. The remarkable fact is that a year ago (June 16, 2003) sensitive earthquake has happened in the same origin place with close values of magnitude and depth.

Alert message about the first earthquake has been sent in 45 minutes after it happened to the duty staff of EMERCOM, Russia. The same kind of message has been sent in 38 minutes after it happened.

Preliminary summurized processing of the first earthquake has been done with data from 26 stations, accurate - from 46. Preliminary summurized processing of the second earthquake has been done with data from 19 stations, accurate - from 43.

Fig. 1 presents fragments of the fitst earthquake's records obtained from digital stations South-Sahalin (delta 14,6 degrees), Petropavlovsk-Kamchatka (delta 25,4 degrees), Magadan (delta 28,1 degrees), Yakutsk (delta 29,2 degrees), Tiksi (delta 38,8 degrees). Fig. 2 presents fragments of records from digital stations Borovoe (delta 50 degrees), Arti (delta 57 degrees), Lovozero (delta 64 degrees), Obninsk (delta 68 degrees), Pulkovo(delta 69 degrees).

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:

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	14-57-16.50	33.19	137.05	10	43	7.50/16	6.40/9	10.5-11		IPC GS RAS (accurate)
2	.0									IPC GS RAS (preliminary)
3	.0									IPC GS RAS (accurate)
4	.0									IPC GS RAS (preliminary)
5	.0									CSEM (accurate)
6	.0									CSEM (accurate)
7	.0									NEIC (accurate)
8	.0									NEIC (preliminary)
9	.0									NEIC (preliminary)
10	.0									NEIC (accurate)

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

Macroseismic manifestations

From ITAR TASS information epicenter was located near the Kii peninsular. Vibrations have been felt on a vast territory, even in Tokyo, which is located 600-700 km. away from the epicenter. Undeground strikes have been registerd in ancient Japanese capital Nara with numerous ancient temples. Local media delivered no messages about destructions of these cultural places. In both cases there ware warnings about danger of tsunami. For the first earthquake the height of sea wave was not more than 60 cm, while for the second strike - nearly one meter. After the first earthquake some temporary stoppage of railroad traffic has been done. A few people were injured but insignificantly. Today the total number of injured is 14 and it seems it will increase. In Vakayama prefecture electricity supply was cut in 600 houses. In Osaka region one fire has bee registered and liquidated. In Mie prefecture 4 ships overturned in sea. No victims have been registered. Fig.3 depicts the map with location of two origins of the earthquakes on September 5. This map shows settlements with points in red with known values of intencities. This map was built with program LAT-2002 developed in CIEKS for account of potential losses from the earthquakes. This program is used in test mode by the Alert Service of GS RAS.

Focal mechanism and seismic moment of the earthquake

Parameters of focal mechanism of these two events which happened in September 05, 2004 (at 10 and 14 hours) have been determined with TMC method in NEIC, USA and in Harvard Center, USA (HARVARD), they are presented in table 2 and shown on figures 4, 5, 6, 7. As one can see solutions of focal mechanism are almost the same for these two different centers. Otigin motion has begun under prevailing actions of expansion force oriented along meridional direction. Both nodal planes have near latitudional spread diraction, NP2 plane has steep fall, NP1 plane is much more flat. Type of motion along both planes - almost "pure" thrust. The value of seismic moment Mo has been determined in IPC GS RAS with P-wave spectra at seismic station Obninsk (delta 69 degrees) and made 8.8* 10** 19 n*m for the first earthquake and 7.3* 10** 19 n*m for the second. THe value of moment magnitude from these data for both earthquakes has made the same value Mw = 7.2 From NEIC data the values of seismic moment for the first earthquake has made 4.0* 10** 19 n*m, the values of moment magnitude - Mw = 7.0; for the second earthquake - Мо=1,.2* 10** 20n*m , - Mw = 7.4. From Harvard data the values of seismic moment for the first earthquake has made 7.9* 10** 19 n*m, the values of moment magnitude - Mw = 7.2; for the second earthquake - Мо=1,.5* 10** 20n*m , - Mw = 7.4.

Table 2

Axes of main strengths

Nodal planes

Center

NP1

NP2

Azm

Stk

Slip

Stk

Slip

IPC GS RAS

IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences