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Information message about the devastating earthquake in the Philippines, July 6, 2017

A devastating earthquake with M = 6.6 occurred in the Philippines on July 6, 2017 at 08:03 GMT (11:03 Moscow time).

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 24 stations, accurate processing - with data from 66.

The red marker on the map displays the epicenter of the earthquake, its focus was located on the territory of the island of Leyte, Philippines, at a depth of 10 km, 8 km south of Yaro, 26 km SW of Tacloban and 27 km E-SE of Kananga.

	Time in origin (GMT)	Latitude, degree	Longitude, degree	Depth, km	Stations number	Ms/N	mb/N	I0 (calculated)	GAP	Center
1	08:03:54.1	11.12	124.8	10.0	66	6.6/32	6.3/45	9-9.5	55	GS RAS(Verified) Federal research center, Geophysical survey of Russian Academy of Sciences
2	08:03:55.5	10.99	124.49	10.0	24		6.4/22	8.5-9		GS RAS(Preliminary) Federal research center, Geophysical survey of Russian Academy of Sciences
3	08:03:58.3	11.11	124.8	10.0	199	Mw 6.5			74	CSEM European - Mediterranean seismological center
4	08:03:57.5	11.11	124.63	6.5	131	Mw 6.5			30	NEIC National Earthquakes Information Center of US Geological Service

Fig. 1 presents fragments of records obtained from digital stations Taejon (∆ 25.3º), Matsushiro (∆ 28.1º), Tennant Creek (∆ 32.3º), Vladivostok (∆ 32.5º), Ussuriysk (∆ 33.5º). Fig. 2 presents fragments of records obtained from digital stations Erimo (∆ 34.7º), Yuzhno-Sakhalinsk (∆ 38.8º), Ulaanbaatar (∆ 39.6º), Yakutsk (∆ 50.9º), Magadan (∆ 52.1º).

Image 1

Image 2

GS RAS registered one aftershock with М=4.8 in 2 hours 28 minutes after the main shock.

N	Time in origin (GMT)	Latitude, degree	Longitude, degree	Depth, km	Stations number	Ms/N	mb/N	I0 (calculated)	Region
20172240	06/07/2017 10:31:49.0.0	11.2	124.95	10.0	16		4.8/10	4.5-5	Leyte, Philippines

According to Associated Press, as a result of the earthquake, two people were killed, about 100 injured. The most affected cities were Yaro and Kananga on the island of Leyte. In the latter, the building collapsed - people were overwhelmed with debris. Because of the earthquake cracks formed on the roads and walls of many buildings, power was cut off, and the residents had to leave their homes. Fig. 1 was obtained from USGS NEIC, it presents USGS Community Internet Intensity Map made by 90 responses in 37 cities.

Image 1

Click here to view detailed macroseismic data (DyfitWeb service)

The focal mechanism solution of the origin in stereographic projection on the lower hemisphere is shown in the table according to the data obtained in USGS NEIC with W-phase Moment Tensor (Mww) technique. The earthquake was caused by the prevalence of tension stresses (PL=0º) oriented to the south (Az=191º). The compression axes are directed to the west (Az=281º). The nodal plane NP1 strikes to the east (Stk=59º), NP2 strikes NW (Stk=324º). Both planes are inclined to the horizon at equal angles (the planes are steeply falling Dp=73º). The type of motion along both planes – slips with fault components (right latteral slip for NP1, left latteral for NP2). According to USGS NEIC Mo=7.056*10**18 N*m, Mww=6,5.

Axes of main strengths			Nodal planes		Center
T	P	N	NP1	NP2	Center
PI: 0 Azm: 191	PI: 25 Azm: 281	PI: 65 Azm: 100	Stk: 59 Dp: 73 Slip: -162	Stk: 324 Dp: 73 Slip: -18	NEIC National Earthquakes Information Center of US Geological Service