Information report about the strong earthquake at southern coast of Taiwan island. |
| On December, 26, 2006 at 12:26p.m. GMT (15:26 Moscow time) the strong earthquake with М=7.4 has taken place at the southern coast of Taiwan island. |
| 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 60 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 29 stations, accurate processing - with data 38 stations. |
| Figure 1 presents fragments of records for this earthquake obtained from digital stations Vladivostok (∆ 23.1º), Yuzhno-Sakhalinsk (∆ 30.7º), Yakutsk (∆ 40.5º), Magadan (∆ 43.2º), Seimchan (∆ 46.2º). Figure 2 presents fragments of records for this earthquake obtained from digital stations Tiksi (∆ 50º), Bilibino (∆ 54º), Arti (∆ 57º), Kislovodsk (∆ 67º), Obninsk (∆ 69º). |
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 |
12-26-19.4 |
21.87 |
120.66 |
10 |
38 |
7.4/16 | 6.9/19 | 10.5-11 | 130 | IPC GS RAS (Accurate) | | 2 |
12-26-19.8 |
21.93 |
120.69 |
10 |
29 |
7.4/14 | 6.9/16 | 10.5-11 | 130 | IPC GS RAS (Preliminary) | | 3 |
12-26-18.9 |
21.8 |
120.52 |
2 |
306 |
7.2Mw | | | 31 | CSEM | | 4 |
12-26-21.5 |
21.82 |
120.53 |
10 |
155 |
7.2/6 | 6.4/59 | | 32 | 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 |
| Epicenter of this earthquake was at the southern coast of Taiwan islands (fig. 3) in 90 kms to a south-southeast from the city of Gaosun (the map has been taken from NEIC WEB site). |
Figure 3 |
|
| Aftershock |
| The earthquake was accompanied with aftershocks. The strongest of them with М=6.7 has taken place in 8 minutes 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 |
| 20064109 | 2006-12-26 12:34:11.0 | 22.01 | 120.74 | 10 | 30 | - | 6.7/ 15 | 9.5 | Taiwan | | 20064110 | 2006-12-26 14:53:14.0 | 21.66 | 120.83 | 10 | 15 | - | 5.2/ 10 | 5.5-6 | Taiwan region | | 20064112 | 2006-12-26 15:41:44.0 | 22.11 | 120.41 | 33 | 21 | 5.3/ 4 | 5.7/ 11 | 5.5-6 | Taiwan | | 20064113 | 2006-12-26 17:35:08.0 | 21.79 | 120.66 | 10 | 25 | 4.8/ 10 | 5.4/ 11 | 6.5-7 | Taiwan region | | 20064115 | 2006-12-27 02:30:36.0 | 22 | 120.51 | 25 | 24 | 5.0/ 12 | 5.9/ 12 | 5.5-6 | Taiwan region | |
| Macroseismic manifestations |
| In accordance with NEIC information NEIC this earthquake has been felt on the whole territory of Taiwan island and in the south-eastern part of China coast. There are destructions and victims, 2 men were killed and more than 30 injured after the destruction of furniture factory. |
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solution of seismic epicenter was obtained with TM method (tensor moment) in the NEIC and with TMC (tensor moment of centroid) method in the Harward Center, USA. The results are presented in table 2 and shown on fig. 4-5. The solutions obtained in these different centers are similar.
The motion in the origin has occurred under the action of prevailing forces of expansion oriented to the northeast direction.
Nodal plane NP1 lies flat and in accordance with NEIC it propagates from the southwest to the northeast, while in accordance with HARVARD - from the southeast to the northwest. The other nodal plane NP2 is oriented in the north-northwest direction and has abrupt falling. Type of the motion is fault (in accordance with NEIC it has left-hand components of shift along NP1 plane and right-hand components of shift along NP2 plane; in accordance with HARVARD it has left-hand components of shift along NP1 plane and "pure” falt along NP2 plane).
The value of seismic moment Мо in accordance with NEIC makes 5.7*10 ** 19 n*m, the value of moment magnitude Mw = 7.1. The value of seismic moment Мо in accordance with Harward makes 3.3 * 10 ** 19 n*m, the value of moment magnitude - Mw = 6.9.
|
| 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 |
| 38 | 72 | 51 | 235 |
8 | 335 | 206 | 11 | -39 | 334 |
83 | -98 | NEIC | | 13 | 62 | 77 | 232 |
2 | 332 | 155 | 32 | -86 | 330 |
58 | -93 | HARVARD | |
| NEIC - National Earthquakes Information Center of US Geological Service |
| HARVARD - Harvard Geophysical Center (USA) |
Figure 4 | 
Figure 5 |
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