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Information message about the destructive earthquake in China November 22, 2014

The destructive earthquake M=6 has occurred on November 22, 2014 at 08:55 GMT (11:55 Moscow time) in Sichuan Province of China. It entailed human casualties and destructions.

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

Preliminary processing has been done with data from 36 stations, accurate processing - with data 54 stations.

Fig. 1 presents fragments of records obtained from digital stations Ulaanbaatar (∆ 18.1º), Talaya (∆ 21.5º), Makanchi Array (∆ 22.3º), Taejon (∆ 22.3º), Ala-Archa (∆ 25º). Fig. 2 presents fragments of records obtained from digital stations Arti (∆ 39.9º), Tiksi (∆ 44.1º), Kislovodsk (∆ 48º), Obninsk (∆ 51.7º), Bilibino (∆ 53º).

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	08-55-24.8	30.2	101.63	10	54	6/31	6/28	8.5	154	IPC GS RAS (Accurate)
2	08-55-27.7	30.46	101.65	10	36		6.2/26	8-8.5	154	IPC GS RAS (Preliminary)
3	08-55-27.4	30.365	101.853	10	516	Mw 6.0			18	CSEM
4	08-55-27.4	30.343	101.72	14.6	281	Mw 5.9	5.8/244		24	NEIC

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

Epicenter

Fig.3 presents with red star epicenter of this earthquake, its origin was located in Sichuan Province of China at the depth of 10 km, 241 km W-S-W of Chengdu, 427 km W-N-W of Chongqing and 637 km N-W of Guiyang.

Figure 3

Aftershock

GS RAS registered one aftershock M=4.3 within the day after the main shock.

N	Date & Time (GMT) yy-mm-dd hh:mm:sec	Lat degr.	Lon degr.	Depth km	N station	Ms/ N	mb/ N	Io calc.	Region
20144273	2014-11-22 18:16:41.0	31.68	104.29	80	15	-	4.3/ 10	-	Sichuan, China

Macroseismic manifestations

According to RIA-Novosti as a result of this earthquake 5 persons were killed and 60 injured including 42 pupils of elementary scholl in Tagun city. 25,000 homes received various damage, more than 6,000 residents were evacuated to safe regions. As previously reported, undeground shocks slightly damaged building of the airport in Kangding, but it did not affect air communication. Telecommunications and power supply system also were not seriously affected, except for the city Tagun, as it was at the epicenter of the earthquake. Fig. 4 was obtained from USGS NEIC, it presents USGS Community Internet Intensity Map, based on 12 responses in 2 cities.

Figure 4

Historical records

Epicenter of this earthquake was located 197 km W-S-W of catastrophic earthquake on May 12, 2008 М=8 , which killed 80,000 persons, and 135 km W of the strongest recent earthquake of Sichuan Province on April 20, 2013 М=7.

Focal mechanism and seismic moment of the earthquake

Focal mechanism solution of the origin was calculated in IPC GS RAS with signs of initial arrivals of P waves at 47 stations, including 21 stations which registered waves of compression (plus signs), and 26 stations which registered waves of expansion (minus signs). These stations are located in the interval of epicentral distances of 2–95º and in azimuth sector of Az=6-350º. Focal mechanism solution in stereographic projection at the lower hemisphere is presented at fig. 5, elements of mechanism are presented in table.2. Fig. 6, 7 present focal mechanism solutions obtained in USGS NEIC with W-phase Moment Tensor (Mww) technique and in Quick CMT Center obtained with CMT technique. All solutions are almost identical. The type of motion in all solutions – slips along both nodal planes. In case of IPC GS RAS - these are slips with fault elements (for NP1 right lateral slip along steeply dipping (DP=87º) and south-west striking (STK-=219º) plane, for NP2 – left lateral and south-east striking (STK-=127º) slip. In Quick CMT solution – similar to IPC GS RAS - these are also slips with fault elements, both planes are vertical DP=82º, NP1 strikes north-west STK= 234º and is characterized by right lateral slip, NP2 strikes south-east STK=143º with left lateral slip. In both cases the earthquake has occurred under the action of close in value tensile and compression stresses, oriented north and east. In USGS NEIC solution there are slips with overthrust elements, NP1 strikes south-east STK= 151º, DP=70º with left lateral slip, NP2 strikes north-east STK= 48º, DP= 59º with right lateral slip. In this solution the earthquake has occurred under prevailing action of compression stresses oriented to the west. Seismic moment of the earthquake obtained in IPC GS RAS with Р wave spectra registered at «Obninsk» (∆51.73º) station makes Мо=1.3*10**18 N*m, Mw=6.0. According to USGS NEIC – Mo=1.05*10**18 N*m, Mw=5.9 and according to Quick CMT Mo=2.05*10**18 N*m, Mw=6.1.

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
20	348	25	88	224	57	219	87	-147	127	57	-4	IPC GS RAS
38	12	7	277	51	178	151	70	33	48	59	156	NEIC
0	8	11	98	79	278	143	82	-8	234	83	-172	Quick CMT

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

NEIC - National Earthquakes Information Center of US Geological Service

Quick CMT - Quick CMT catalog

Figure 5	Figure 6

Figure 7