Information message about the strong earthquakes in the area of Santa-Cruz Islands of Solomon Islands on February 6, 2013. |
| The strong earthquake with M=7.2 has occurred on February 6, 2013 at 01:12 GMT (05:12 Moscow time) in the region of Santa-Cruz Islands, Solomon Islands. The body-wave magnitude was mb=6.5. Shock at 01:23, in 11 minutes after it, has been registered with mb=6.7 and the third shock has been registered at 01:54 with mb=6.4 |
| Preliminary processing has been done with data from 37 stations, accurate processing - with data 43 stations. |
| Fig. 1 presents fragments of not filtered records obtained from digital stations Magadan (∆ 70.8º), Ulaanbaatar (∆ 77.5º), Talaya (∆ 81.3º), Tiksi (∆ 85.4º), Kurchatov (∆ 95.8º). Fig. 2 presents filtered fragments used for determination of initial arrivals obtained from digital stations Yuzhno-Sakhalinsk (∆ 70.8º), Petropavlovsk (∆ 63.6º), Kuldur (∆ 66.4º), Magadan (∆ 70.8º), Seimchan (∆ 73.9º). |
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 |
01-54-12.9 |
-10.54 |
165.76 |
10 |
30 |
| 6.4/14 | 8.5-9 | 129 | IPC GS RAS ([3]) | | 2 |
01-23-19.3 |
-10.8 |
164.98 |
10 |
38 |
| 6.7/16 | 9.5 | 129 | IPC GS RAS ([2]) | | 3 |
01-12-22.4 |
-10.55 |
165.09 |
10 |
43 |
7.2/30 | 6.5/19 | 10-10.5 | 66 | IPC GS RAS ([1]) | | 4 |
01-54-15.7 |
-10.462 |
165.731 |
10 |
199 |
Mw 7.0 | | | 43 | CSEM ([3]) | | 5 |
01-23-22.1 |
-11.148 |
164.986 |
20 |
344 |
| 6.5 | | 35 | CSEM ([2]) | |
| IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences |
| CSEM - European - Mediterranean seismological center |
| Epicenter |
| Fig. 3 presents with red star epicenter of the first shock which origin was located in the area of Santa Cruz Island, Solomon Islands, at the depth of 10 km, 80 km W-N-W of Lata, Nendo Islands, Santa Cruz Islands. The yellow star presents epicenter of the second earthquake which origin was located 90 km W-S-W of Lata. The green star presents epicenter of the third earthquake which origin was located 20 km N-N-W of Lata. |
Figure 3 |
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| Aftershock |
| GS RAS registered 2 foreshocks and 52 aftershocks with M≥5.2 within the day of these earthquakes.
The table below presents foreshocks and most significant aftershocks with М>5.5 which were registered within initial 6 hours.
|
| 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 |
| 20130412 | 2013-02-06 00:07:20.0 | -10.75 | 165.1 | 10 | 30 | - | 5.7/ 12 | 7-7.5 | Santa Cruz Islands | | 20130421 | 2013-02-06 00:45:58.0 | -11.01 | 165.09 | 10 | 13 | - | 5.2/ 7 | 5.5-6 | Santa Cruz Islands | | 20130420 | 2013-02-06 01:16:38.0 | -10.76 | 164.74 | 10 | 27 | - | 6.1/ 16 | 8 | Santa Cruz Islands region | | 20130424 | 2013-02-06 01:22:10.0 | -11.41 | 165.51 | 10 | 25 | - | 5.7/ 14 | 7-7.5 | Santa Cruz Islands | | 20130422 | 2013-02-06 01:33:35.0 | -10.76 | 165.23 | 10 | 16 | - | 5.6/ 9 | 6.5-7 | Santa Cruz Islands | | 20130415 | 2013-02-06 01:48:41.0 | -11.45 | 165.8 | 10 | 27 | - | 5.8/ 17 | 7-7.5 | Santa Cruz Islands | | 20130419 | 2013-02-06 02:30:42.0 | -10.77 | 164.89 | 10 | 28 | - | 5.8/ 16 | 7-7.5 | Santa Cruz Islands region | | 20130426 | 2013-02-06 02:58:19.0 | -10.61 | 164.93 | 10 | 23 | - | 5.7/ 14 | 7-7.5 | Santa Cruz Islands region | | 20130436 | 2013-02-06 03:49:44.0 | -10.8 | 165.4 | 10 | 27 | - | 5.8/ 15 | 7-7.5 | Santa Cruz Islands | | 20130431 | 2013-02-06 06:35:18.0 | -10.77 | 164.46 | 10 | 38 | - | 6.0/ 19 | 7.5-8 | Santa Cruz Islands region | | 20130432 | 2013-02-06 06:53:18.0 | -10.58 | 164.93 | 10 | 35 | - | 5.8/ 15 | 7-7.5 | Santa Cruz Islands region | |
| Macroseismic manifestations |
| In accordance with RIA-Novosti a few settlements at Solomon Islands were destroyed. Five persons were killed, a few persons went missing.
Fig. 4 shared from USGS NEIC , presents USGS Community Internet Intensity Map by 6 responses in 4 cities. Pacific Ocean Center of Tsunami warning anonced Tsunami alert, the maximum height of tsunami wave of 91 cm was noticed in Lata, at Nendo Island, Santa Cruz Islands.
|
Figure 4 |
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| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solutions for the origin of the earthquake which occurred on February 6, 2013 at 01:12 were obtained with CMT method in NEIC – USGS and in Global CMT Catalog Center, USA. These solutions are presented in table 2 and figures 5,6. Both solutions are almost identical. The earthquake has occurred under the action of S-W oriented compression forces. Both nodal planes have nearly along meridian direction of propagation. One of them (NP1) – lays flat (DP=21-28º), the type of motion along it is characterized by overthrust with left side slip component, another plane (NP2) is steeply falling (DP=64-70º), the type of motion along it - uplift. The value of seismic moment Мо in accordance with USGS makes Mo=7.8*10**20 N*m, the value of moment magnitude Mw=7.9; in accordance with Global CMT Catalog – Mo=8.65*10**20 N*m, Mw=7.9. |
| 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 |
| 68 | 88 | 19 | 237 |
10 | 331 | 311 | 28 | 68 | 156 |
64 | 101 | NEIC | | 64 | 71 | 25 | 236 |
6 | 329 | 314 | 21 | 74 | 151 |
70 | 96 | Quick CMT | |
| NEIC - National Earthquakes Information Center of US Geological Service |
| Quick CMT - Quick CMT catalog |
Figure 5 | 
Figure 6 |
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