Information report about appreciable earthquake on August 24, 2006 at the east coast of southern Kamchatka |
| The appreciable earthquake with magnitude М=6.4 has taken place on August 24, 2006 at 21:50 GMT in the south of Kamchatka Peninsula to the east from the coast in the sea.
|
| 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 40 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 43 stations, accurate processing - with data 51 stations. |
| Fig. 1 presents fragments of records obtained from this earthquake by digital stations Petropavlovsk (∆ 2.1º), Yuzhno-Sakhalinsk (∆ 10.5º), Yakutsk (∆ 18.7º), Tiksi (∆ 24.3º), College (∆ 30.9º). Fig. 2 presents fragments of records obtained from this earthquake by digital stations Ulan-Bator (∆ 32.5º), Borovoe (∆ 50.5º), Arti (∆ 53.9º), Obninsk (∆ 63.4º), Kislovodsk (∆ 69.8º). |
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 |
21-50-35.4 |
51.09 |
157.55 |
55 |
43 |
6.4/13 | 5.9/13 | 6.5 | 78 | IPC GS RAS (preliminary) | | 2 |
21-50-35.8 |
51.07 |
157.57 |
60 |
51 |
6.4/17 | 6/17 | 6-6.5 | | IPC GS RAS (accurate) | | 3 |
21 50 36.3 |
51.111 |
157.768 |
60 |
279 |
| 6.1 | | 117 | CSEM | | 4 |
21 50 39.8 |
51.188 |
157.523 |
70 |
|
| 6.0/76 | | | NEIC (accurate) | | 5 |
21 50 37.1 |
51.01 |
158.01 |
40 |
|
Mc6.4 | | | | KRIPC | |
| 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 |
| KRIPC - Regional Informational Processing Center of Kamchatka |
| Epicenter |
| Epicenter of this earthquake was located in the south part of seashore area of Kamchatka Peninsula, in the seismic active area of Kurilo-Kamchatsky region. Fig.2 presents location of epicenter on the map of known seismic activity in accordance with data from "Specialized catalogue of the earthquakes of Northern Eurasia " (ed. N.V.Kondorskaya and V.I.Ulomov, 1996) and Operative seismological catalogue of GS RAS, for the period 1737-2006. |
Figure 3 |
|
| Macroseismic manifestations |
| This earthquake was felt in Severo-Kurilsk with intensity 5-6, in Petropavlovsk–Kamchatsky - 3-4 balla
|
| Historical records |
| Epicenter of this earthquake was located in the south part of origin zone of one of the strongest earthquakes in Kamchatka, which has happened on June 25, 1904 with M=7.7 and was accompanied with tsunami in Avachinsk Bay (fig.3).
The note to the figure 3 has been taken from monograph of academician S.A.Fedotov “Long term seismic forecast for Kurilo-Kamchatka bow”, 2005:
Fig.3. Origin zones of the strongest Kurilo-Kamchatka earthquakes (M=7.75) for the period 1904-1963 and potential places of the future earthquakes with M>=7.75(S.A.Fedotov, 2005 “Long term seismic forecast for Kurilo-Kamchatka bow”, p.64)
1 - instrumental epicenters of the strong earthquakes; 2 – boundaries of the origin zones of the strong earthquakes; 3 – uncertain parts of boundaries of the origin zones; 4 – potential places of the origin zones; 5 – supposed origin zones of catastrophic earthquakes of the last century;
6 – aftershocks of the earthquake 1.V 1915
7 – aftershocks of the earthquake 30.1 1917
8 – aftershocks of the earthquake 7.IX 1918
9 – aftershocks of the earthquake 3.II 1923
10 – strong foreshocks of the earthquakes 1923
and of 1963; 11 – boundary areas of tsunami; 12 – most probable places of the future earthquakes with M >=7.75; 13 – less probable places of the earthquakes with M=7.75; 14 –distance readout line along the area of focal zone exit to the bottom of Pacific ocean; 15 - axes of deep-water hollows; 16-axis of Kurilo-Kamchatka volcanic belt.
|
Figure 4 |
|
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solution was calculated in GS RAS from the first sighs of P-wave arrivals at 45 stations, where 38 of them registered the waves of compression (plus signs) and 7 – the waves of expansion (minus signs). These stations are located at epicentral distances of 1-80 degrees with rather uniform distribution along the azimuths. Focal mechanism solution in stereographical projection at lower hemisphere is given at figure 5, elements of focal mechanism are presented in table 2. Figure 6 presents focal mechanism solution of the origin calculated with TMC method in NEIC, Geological Service, USA. As one can see, the solutions obtained from different techniques are rather close. The motion in origin has happened under the action of compression forces , oriented in the south-east direction. Type of the motion – thrust. Both nodal planes have north-north-east direction of propagation coinciding with spread direction of Kurilo-Kamchatka ridge. Seismic moment Mo of the earthquake 24.08.2006 has been determined from spectra of P-waves registered by IRIS digital stations Arti (ARU) and Obninsk (OBN), located at the distances 54 and 63 degrees respectively. The averaged value of Mo makes 2.0 E 19 n*m. The value of moment magnitude Mw calculated from Kanamori formula makes Mw=6.8. The value Mo obtained in NEIC makes Mo=6.1 E 18 n*m, Mw=6.5; As one can see, the values Mo and Mw obtained with different techniques are close and within the range of permitted error.. |
| 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 |
| 73 | 250 | 13 | 111 |
11 | 18 | 215 | 34 | 109 | 12 |
58 | 78 | IPC GS RAS | | 79 | 286 | 10 | 127 |
4 | 36 | 222 | 35 | 97 | 33 |
55 | 85 | NEIC | |
| IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences |
| NEIC - National Earthquakes Information Center of US Geological Service |
Figure 5 | 
Figure 6 |
|
