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Information message about the strong earthquake on November 17, 2023 in the Philippines

An earthquake (significant at the epicenter on the SIS-17 scale) with M=6.4 occurred on November 17, 2023 at 08:14 a.m. GMT (11:14 a.m. Moscow time) in the Philippines.<br /> SIS-17 - Earthquakes. Seismic intensity scale. State Standard 57546–2017.

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 12 min after registration to the Ministry of Emergency of the Russian Federation (EMERCOM).

Preliminary processing has been done with data from 11 stations, accurate processing - with data from 69.

The red marker on the map is the epicenter of the earthquake, the origin of which was located on the southern coast of the island of Mindanao, Philippines at a depth of 65 km, 54 km S-SW of General Santos, 171 kilometers S-SW of Davao and 1082 km S-SE of Manila, the capital of the Philippines.

	Time in origin (GMT)	Latitude, degree	Longitude, degree	Depth, km	Stations number	Ms/N	mb/N	I0 (calculated)	GAP	Center
1	08:14:12.0	5.66	125.01	65.0	69	6.4/39	6.7/50	6-6.5	133	GS RAS(Verified) Federal research center, Geophysical survey of Russian Academy of Sciences
2	08:14:04.1	5.54	124.91	10.0	11		6.8/10	9.5-10		GS RAS(Preliminary) Federal research center, Geophysical survey of Russian Academy of Sciences
3	08:14:13.2	5.64	125.1	70.0	539	Mw 6.7	6.4/309		18	CSEM European - Mediterranean seismological center
4	08:14:13.2	5.59	125.05	78.0	117	Mw 6.7/41	6.6/368		21	NEIC National Earthquakes Information Center of US Geological Service

Fig. 1 presents fragments of records obtained from digital stations Kappang (∆ 11.8º), Tennant Creek (∆ 27º), Taejon (∆ 30.7º), Matsushiro (∆ 33º), Vladivostok (∆ 37.8º). Fig. 2 presents fragments of records obtained from digital stations Kuldur (∆ 43.8º), Talaya (∆ 49.2º), Severo-Kurilsk (∆ 51.8º), Yakutsk (∆ 56.4º), Magadan (∆ 57.3º).

Image 1

Image 2

Accrding to TASS, 11 people died as a result of the earthquake, another 730 local residents were injured. The consequences of the earthquake affected the lives of at least 16,293 residents of the Davao and Sokxxarhen regions. About 97 houses were completely destroyed, more than 700 were partially damaged. At least 3 of the 12 roads in Sokkssarhen were impassable.
Figure 1 was obtained from USGS NEIC, it presents USGS Community Internet Intensity Map made by 63 responses in 34 cities.

Image 1

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 88 stations, including 73 stations which registered compression waves (plus signs), and 15 stations which registered tensile waves (minus signs). The stations are located in the interval of epicentral distances1.5-95.7º and in azimuth sector Az=1-358º. 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 W-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 occurred under the influence of prevailing compression stresses oriented to the east (AZ=81-82º). One nodal plane NP1 strikes north (STK=4-9º), another plane NP2 – strikes S-SE (STK=153-157º), both planes are dipping to the horizon at close angles (DIP=45-50º). The type of motion along both planes – reverse fault. Seismic moment according to USGS NEIC makes Mo=1.506 *10**19 N*m, Mww=6.7. According to LDEO GCMT it makes Mo=1.8*10**19 N*m, Mw=6.8.

Axes of main strengths			Nodal planes		Center
T	P	N	NP1	NP2	Center
PI: 76 Azm: 351	PI: 0 Azm: 81	PI: 14 Azm: 171	Stk: 4 Dp: 47 Slip: 110	Stk: 157 Dp: 47 Slip: 70	GS RAS Federal research center, Geophysical survey of Russian Academy of Sciences
PI: 75 Azm: 351	PI: 0 Azm: 81	PI: 15 Azm: 171	Stk: 6 Dp: 47 Slip: 111	Stk: 157 Dp: 47 Slip: 69	NEIC National Earthquakes Information Center of US Geological Service
PI: 71 Azm: 344	PI: 3 Azm: 82	PI: 19 Azm: 173	Stk: 9 Dp: 50 Slip: 115	Stk: 153 Dp: 45 Slip: 63	GCMT Lamont-Doherty Earth Observatory Global CMT Columbia University, USA

The earthquake occurred 115 km south-southwest of the strong earthquake of December 15, 2019 with M=6.8, 125 km south of the strong earthquake of October 29, 2019 with M=6.5 and 143 km S-SW of the devastating earthquake of October 31, 2019 with M=6.6.