Fig. 1 presents fragments of records obtained from digital stations Petropavlovsk (∆ 1º), Severo-Kurilsk (∆ 3.7º), Yuzhno-Sakhalinsk (∆ 12.9º), Yuzhno-Kurilsk (∆ 13.3º), Bilibino (∆ 15.1º). Fig. 2 presents fragments of records obtained from digital stations Tiksi (∆ 22.9º), Talaya (∆ 33.8º), Norilsk (∆ 35.8º), Arti (∆ 53.4º), Obninsk (∆ 62.4º).

Image 1

Image 2

The aftershock process following the Kamchatka mega-earthquake of July 29 with M=8.2 continues. A new strong aftershock occurred on September 18 at the northern flank of the focal zone. Following this, 40 earthquakes with magnitudes greater than 4.5 were recorded within five hours. Events with magnitudes greater than 5 are listed below. The following earthquakes of these were felt: at 19:08 in Yelizovo with a magnitude of 3 MSK, at 19:19 in Petropavlovsk-Kamchatsky with magnitude of 2-3 MSK, at 19:38 in Petropavlovsk-Kamchatsky with magnitude of 2 MSK, at 20:17 in Petropavlovsk-Kamchatsky with magnitude of 2-3 MSK, at 20:52 in Petropavlovsk-Kamchatsky with magnitude of 2 MSK, at 21:37 in Petropavlovsk-Kamchatsky with magnitude of 2 MSK, at 22:10 in Petropavlovsk-Kamchatsky with magnitude of 2 MSK, at 22:17 in Petropavlovsk-Kamchatsky with magnitude of 2 MSK, at 22:37 in Petropavlovsk-Kamchatsky with magnitude of 2 MSK, at 22:20 in Petropavlovsk-Kamchatsky with magnitude of 2 MSK, at 22:21 in Petropavlovsk-Kamchatsky with magnitude of 2 MSK, at 22:22 in Petropavlovsk-Kamchatsky with magnitude of 2 MSK, at 22:23 in Petropavlovsk-Kamchatsky with magnitude of 2 MSK, at 22:25 in Petropavlovsk-Kamchatsky with magnitude of 2 MSK, at 22:26 in Petropavlovsk-Kamchatsky with magnitude of 2 MSK, at 22:27 in Petropavlovsk-Kamchatsky with magnitude of 2 MSK, at 22:28 in Petropavlovsk-Kamchatsky with magnitude of 2 MSK, at 22:29 in Petropavlovsk-Kamchatsky with magnitude of 2 MSK, at 22:38 in Petropavlovsk-Kamchatsky with magnitude of 2 MSK, at 22:39 in Petro 1 hour 50 minutes in Petropavlovsk-Kamchatsky with magnitude of 2 MSK, at 23 hours 10 minutes in Petropavlovsk-Kamchatsky with magnitude of 2-3 MSK, at 23 hours 15 minutes in Petropavlovsk-Kamchatsky with magnitude of 2 MSK.

According to Kamchatka Branch of GS RAS the earthquake was felt at Cape Shipunsky with a magnitude of 6 and in the following populated areas: Petropavlovsk-Kamchatsky, Rybachy with a magnitude of 6, Vilyuchinsk, Elizovo, Nikolaevka with a magnitude of 5-6, Zaozerny, Koryaki, Zeleny, Paratunka with a magnitude of 5, Apacha, Klyuchi, Milkovo, Pauzhetka with a magnitude of 4, Oktyabrsky with a magnitude of 3-4, Kavalerskoye, Severo-Kurilsk, Ust-Kamchatsk with a magnitude of 3, Nikolskoye with a magnitude of 2-3.
According to TASS, a tsunami warning was issued along the eastern coast of the Kamchatka Peninsula. A wave approximately 30 cm high reached the mouth of the Nalychevo River. The tsunami warning was later cancelled.

Click here to view detailed macroseismic data (DyfitWeb service)

Focal mechanism solution of the origin was calculated by GS RAS with signs of initial arrivals of P waves at 103 stations, including 87 stations which registered compression waves (plus signs), and 16 stations which registered tensile waves (minus signs). The stations are located in the interval of epicentral distances 1-94.7º and in azimuth sector Az=7-352º. Focal mechanism solution in stereographic projection on the lower hemisphere and elements of the mechanism are presented in the table. The table also contains focal mechanism solutions obtained at the USGS NEIC with WW-phase Moment Tensor (Mww) technique and in Lamont-Dohert Earth Observatory of Columbia University, USA (LDEO GCMT) with СМТ (Centroid moment tensor) technique. Solutions from different centers are close. The earthquake was caused by predominantly south-east oriented compression stresses. (AZ=124-128º). One nodal plane NP1 strikes S-SW (STK=194-212º), another NP2 – strikes NE (STK=38-42º). NP1 plane is more horizontal (DP=15-21º) if compared with NP2 (DP=71-75º). The type of motion along NP1 – thrust, along NP2 – reverse fault. The seismic moment of the earthquake was obtained by GS RAS from the spectra of longitudinal waves registered at the station "Talaya" (∆ 33.8º), it makes Mo=5.461*10**20 N*m, Mw=7.8. The seismic moment according to USGS NEIC makes Mo=6.846*10**20 N*m, Mww=7.82. According to LDEO GCMT it makes Mo=7.91*10**20 N*m, Mw=7.9.