Information message about the strong earthquake in Taiwan February 5, 2016 |
| The strong earthquake M=6.5 has occurred on February 5, 2016 at 19:57 GMT (22:57 Moscow time) in Taiwan. |
| 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 66 stations, accurate processing - with data 73 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Taejon (∆ 14.7º), Matsushiro (∆ 20.4º), Mys Shultsa (∆ 21.6º), Vladivostok (∆ 22.3º), Erimo (∆ 26.8º). Fig. 2 presents fragments of records obtained from digital stations Ulaanbaatar (∆ 27.3º), Kuldur (∆ 27.8º), Yakutsk (∆ 39.7º), Zalesovo Group (∆ 41.2º), Magadan (∆ 42.4º). |
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 |
19-57-24.7 |
22.88 |
120.74 |
20 |
73 |
6.5/40 | 6.4/45 | 8-8.5 | 81 | IPC GS RAS (Accurate) | | 2 |
19-57-24.1 |
22.81 |
120.74 |
20 |
66 |
6.5/35 | 6.5/38 | 8-8.5 | 107 | IPC GS RAS (Preliminary) | | 3 |
19-57-27.8 |
22.93 |
120.54 |
17 |
43 |
Mw 6.4 | | | 55 | CSEM | | 4 |
19-57-27.7 |
22.87 |
120.67 |
23 |
192 |
Mw 6.4 | 6.2/99 | | 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 the epicenter of this earthquake, its origin was located in the southern part of Taiwan Island, at a depth of 20 km, 50 km E-N-E of Kaoshsiung City, 58 km E-S-E of Tainan and 147 km S of Taichung. |
Figure 3 |
|
| Macroseismic manifestations |
| According to ITAR-TASS as a result of the earthquake, 37 people were killed and 110 are missing.
Tainan city was most severely affected by the earthquake (Fig.4).
Fig. 5, was obtained from USGS NEIC , it presents USGS Community Internet Intensity Map made by 135 responses in 46 cities. |
Figure 4 | 
Figure 5 |
|
| Historical records |
| The epicenter was located 33 km S-W of the epicenter of strong earthquake of September 20, 1999 М=7.7. At that time more than 1500 people died and 3800 were injured. Puli was almost completely destroyed. |
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solution of the origin of earthquake was obtained in IPC GS RAS with signs of initial arrivals of P waves at 62 stations, including 32 stations which registered compression waves (plus signs) and 30 stations which registered tensile waves (minus signs). These stations are located in the interval of epicentral distances of 0.5–96.4º and azymuth sector Az=3-359º. Focal mechanism in stereographic projection at lower hemisphere obtained in IPC GS RAS is presented at fig.6 and elements of mechanism are given in table 2. Fig. 7,8 present focal mechanism solutions obtained in USGS NEIC with W-phase Moment Tensor (Mww) technique and in Quick CMT Catalog Center, USA obtained with CMT technique. All solutions are close. This earthquake has occurred under prevailing action of compression stress oriented south-west and tensile stress oriented south-east. Nodal plane NP1 in all solutions is almost vertical (DP=75º-84º), it strikes to the south (STK=169º-182º); NP2 is more flat (DP=17º-25º) it strikes north-west (STK=281º-299º). The type of motion along steeply dipping plane NP1 – reverse fault with right latteral slip component, along NP2 – left latteral slip with thrust component.
Seismic moment of earthquake was obtained in IPC GS RAS with spectra of Р-waves at «Obninsk» station (∆68.33º) Мо=3.9*10**18 N*m, Mw=6.4; according to USGS NEIC – Mo=4.26*10**18 N*m, Mw=6.35; according to СМТ – Mo=5.05*10**18 N*m, Mw=6.4. |
| 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 |
| 49 | 109 | 37 | 258 |
16 | 0 | 182 | 84 | 106 | 293 |
17 | 22 | IPC GS RAS | | 55 | 109 | 27 | 248 |
19 | 349 | 174 | 75 | 110 | 299 |
25 | 38 | NEIC | | 50 | 104 | 32 | 241 |
22 | 345 | 169 | 80 | 112 | 281 |
24 | 24 | 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 |
|
