Information message about the strong earthquake in the region of Vanuatu Islands, New Hebrides, December 25, 2010. |
| The strong earthquake with М=7.5 has occurred on December 25,2010 at 13:16 GMT (16:16 Moscow time) in the region of Vanuatu Islands of New Hebrides. |
| 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 20 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 42 stations, accurate processing - with data 51 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Port Moresby (∆ 22.6º), Tennant Creek (∆ 31.6º), Matsushiro (∆ 62.7º), Erimo (∆ 65.6º), Yuzhno-Sakhalinsk (∆ 70.2º). Fig. 2 presents fragments of records obtained from digital stations Hailar (∆ 81º), Ulaanbaatar (∆ 86.6º), Yakutsk (∆ 87º), Talaya (∆ 90.5º), College (∆ 90.9º). |
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 |
13-16-35.1 |
-19.78 |
167.93 |
10 |
51 |
7.5/32 | 7.3/16 | 10.5-11 | 110 | IPC GS RAS (Accurate) | | 2 |
13-16-35.2 |
-19.74 |
167.98 |
10 |
42 |
7.5/32 | 7.3/14 | 10.5-11 | 181 | IPC GS RAS (Preliminary) | | 3 |
13-16-37.0 |
-19.79 |
167.99 |
10 |
480 |
Mw 7.5 | | | 23 | CSEM | | 4 |
13-16-37.0 |
-19.775 |
167.895 |
12.3 |
173 |
Mw 7.3 | 6.7/144 | | 43 | 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, which origin was located in Pacific Ocean in the region of Vanuatu Archipelago at the depth of 10 km, in 315 km E-N-E of Numea, New Caledonia, in 233 km S-S-W of Port Vila, capital of Vanuatu.
|
Figure 3 |
|
| Aftershock |
| This earthquake was accompanied with aftershocks. GS RAS registered 22 aftershocks with М>=5 within two days after the main shock. The table presents most significant of them. |
| 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 |
| 20104340 | 2010-12-25 13:59:10.0 | -19.27 | 167.96 | 70 | 23 | - | 5.6/ 12 | 3.5-4 | Vanuatu Islands region | | 20104344 | 2010-12-25 14:44:33.0 | -19.24 | 168.06 | 10 | 16 | - | 5.6/ 9 | 6.5-7 | Vanuatu Islands | | 20104366 | 2010-12-26 02:13:36.0 | -19.47 | 168.4 | 10 | 31 | 5.6/ 13 | 6.1/ 12 | 7.5-8 | Vanuatu Islands | | 20104370 | 2010-12-26 06:17:56.0 | -19.81 | 168.24 | 10 | 24 | - | 5.5/ 11 | 6.5-7 | Vanuatu Islands | | 20104382 | 2010-12-26 19:38:24.0 | -19.87 | 168.1 | 33 | 28 | - | 6.0/ 8 | 6 | Vanuatu Islands | |
| Macroseismic manifestations |
| Fig. 4, downloaded from NEIC USA presents the map with intensities composed with phone calls to 41 respondents living in 6 places.
|
Figure 4 |
|
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solutions of this earthquake which occurred on December 25, 2010 were calculated with CMT method in NEIC USA, USGS and in Global CMT Catalog, USA, they are shown in stereographic projection at lower hemisphere in figures 5, 6, elements of solution are presented in table 2. These solutions obtained in different centers with various techniques are almost similar. The earthquake has occurred under the action of N-E oriented expansion forces. The type of motion along both nodal planes – fault with shift components (right shift along NP1 plane and left shift along NP2). NP1 plane propagates S-E direction, NP2 – almost along meridian. Declination angles of both nodal planes are close and make DP =45º-52º.
The value of seismic moment Мо for this earthquake which occurred on December 25, 2010 in accordance with USGS makes 1.3*10**20 n*m, the value of moment magnitude makes Mw=7.3, in accordance with Global CMT Catalog – Мо=9.69*10**19 n*m, Mw=7.3.
|
| 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 |
| 1 | 74 | 63 | 342 |
27 | 165 | 139 | 50 | -127 | 9 |
52 | -55 | NEIC | | 2 | 74 | 76 | 337 |
14 | 165 | 150 | 45 | -111 | 358 |
48 | -71 | Quick CMT | |
| NEIC - National Earthquakes Information Center of US Geological Service |
| Quick CMT - Quick CMT catalog |
Figure 5 | 
Figure 6 |
|
