Information messageabout the earthquake in China (Southern Sinzian) on November 14, 2001 |
| On November 14, 2001 the strong earthquake has happened in Southern Sinzian of China. It occurred at 12:26 Moscow time (09:26 GMT) and had magnitude 7.6. |
| 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 44 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 16 stations, accurate processing - with data 33 stations. |
| Figures 1-2 present fragments of records obtained by IPC from digital stations in a near to real time mode.
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Figure 1
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Figure 2
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| 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 |
09-26-14.70 |
36 |
90 |
33 |
16 |
7.50/9 | 5.80/10 | 8.5-9 | | IPC GS RAS (preliminary) | | 2 |
09-26-11.5 |
36 |
90 |
10 |
33 |
7.6/16 | 5.7/9 | 8.5-9 | | IPC GS RAS (accurate) | | 3 |
09-26-10.8 |
36 |
90 |
10 |
208 |
7.4-8.1 | 5.7-6.6 | | | CSEM | | 4 |
09-26-14.85 |
35 |
90 |
33 |
90 |
| 5.6/44 | | | NEIC (preliminary) | | 5 |
09-26-10.25 |
36 |
90 |
10 |
263 |
8.1/88 | 6.1/59 | | | NEIC (accurate) | |
| 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 |
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism of the earthquake 14.11.2001 has been calculated in CEME GS RAS from the signes of initial Р-wave arrivals at 30 stations, which are located at hypocenter intervals of 14-86 degrees with their rather uniform dispersion along the azimuth from 16 to 333 degrees. Parameter obtained in IPC GS RAS, as well as parameters of focal mechanism obtained from CMT method in Harvard Geophysical Laboratory USA (HRV solution) and in NEIC USAare presented in table 2 and shown on figures 3-5.
As it is seen, all of these solutions have common features: one of nodal planes with close to meridian spread direction has steep slope, either thrust-shift components prevail in origin motions or purely thrust under the action of expanding strengths or combination of compression-expansion strengths. Location of the second nodal plane is different for different authors.
Average value of seismic moment Мо for this earthquake determined in IPC GS RAS from spectra of Р-waves at two seismic stations: Obninsk (delta=41.1o), Kislovodsk (delta=37.1o) made 2.1* 10** 19 n*m (2.1* 10**26 D-CM). The value of moment magnitude from this data made - Mw =6.8.
Seismic moment value Мо of this earthquake obtained in Harvard made 5.8* 10** 20 n*m, the value of moment magnitude Mw from these data - Mw=7.8.
Seismic moment value Мо of this earthquake obtained in NEIC made 3.5* 10** 20 n*m, the value of moment magnitude Mw from these data - Mw=7.7.
As it is seen, the values of Мо and Мw determined in IPC GS RAS differ in times from those determined in Harvard and NEIC. This may be because of different methods used in getting Мо: IPC has analyzed interval of recording for longitudinal waves from Р-waves arrivals till РР-waves, while estimation of Мо with СМТ method takes into account the whole record including longitudinal, cross and surface waves. For this earthquake significant differences also are observed in magnitudes determined from longitudinal (Мb) and surface (Ms) waves. Мb made 5.8- 6.1 and Ms 7.6-8.1.
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| 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 |
| 11 | 264 | 58 | 155 |
29 | 360 | 322 | 42 | -137 | 197 |
62 | -56 | IPC GS RAS | | 41 | 289 | 49 | 107 |
1 | 198 | 32 | 4 | -76 | 198 |
86 | -91 | NEIC | | 20 | 318 | 29 | 59 |
53 | 198 | 96 | 54 | -7 | 190 |
84 | -144 | HARVARD | |
| IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences |
| NEIC - National Earthquakes Information Center of US Geological Service |
| HARVARD - Harvard Geophysical Center (USA) |
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