Information message about the strong earthquake in New Zealand July 21, 2013 |
| The strong earthquake with magnitude of M=6.5 has occurred in New Zealand on July 21, 2013 at 05:09 GMT (9:09 Moscow time). |
| 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 30 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Fig. 1 presents fragments of records obtained from digital stations Port Moresby(∆ 40.2º), Tennant Creek (∆ 40.3º), Sanae (∆ 66.9º), Erimo (∆ 88.0º). Fig. 2 presents fragments of records obtained from digital stations Taijon (∆ 88.9º), Yuzhno-Sakhalinsk (∆ 92.7º), Petropavlovsk (∆ 95.3º), Kuldur (∆ 98.1º). |
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 |
05-09-28.5 |
-41.69 |
174.63 |
10 |
28 |
6.5/18 | 6.3/7 | 9-9.5 | 93 | IPC GS RAS | | 2 |
05-09-30.3 |
-41.699 |
174.489 |
2 |
35 |
6.6 Mw | | | 129 | CSEM | | 3 |
05-09-31.3 |
-41.742 |
74.447 |
14 |
97 |
6.5 Mw | | | 59 | 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 |
| Red star in Figure 3 shows the epicenter of this earthquake, the origin of which was located in Cook Strait, New Zealand, at a depth of 10 km, 43 km to the SSW of Wellington, the capital of the state, 124 km to the ESE of Nelson and 263 km NE of Christchurch. |
Figure 3 |
|
| Aftershock |
| Geophysical Survey registered the foreshock with M=5.9 for 10 hours before the main shock and 10 hours after - aftershock with M=4.8 |
| 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 |
| 20132646 | 2013-07-20 19:17:08.0 | -41.65 | 174.62 | 10 | 21 | - | 5.9/ 6 | 7.5-8 | Cook Strait, New Zealand | | 20132657 | 2013-07-21 15:15:13.0 | -41.16 | 174.53 | 10 | 11 | - | 4.8/ 5 | 4.5-5 | Cook Strait, New Zealand | |
| Macroseismic manifestations |
| According to ITAR-TASS the rail service in New Zealand was interrupted by the earthquake. New Zealand media reported that specialists check lines, bridges and tunnels. Wellington Airport is operating normally, but the airport staff warn passengers about the possible delay of some flights. The tremors have not led to serious damage or casualties, but caused panic among the residents of the New Zealand capital. In social networks, posted a lot of photos, which capture the effects of the earthquake - overturned furniture in offices and homes, scattered from the shelves of products in supermarkets, broken glass. According to reports, as a result of the disaster suffered only one person.
Fig. 4 presents USGS Community Internet Intensity Map obtained from site of USGS NEIC, based on 30 responses in 17 cities. |
Figure 4 |
|
| Historical records |
| The epicenter was located 280 kilometers NE of the epicenter of the devastating earthquake February 21, 2011 with М=6.3 (Fig. 5, yellow star) near the city of Christchurch, which killed 185 people. |
Figure 5 |
|
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solutions were obtained in USGS NEIC with USGS Body-Wave Moment Tensor Solution and in Quick CMT Catalog, USA, with CMT technique. These solutions are shown in Fig. 6.7 in stereographic projection at the lower hemisphere, elements of mechanism are presented in table 2. All solutions are close. The earthquake has occurred under the action of W-E oriented compression stresses. The stresses of expansion were oriented to the south. Both nodal planes were steeply declining (DP=58-78º), NP1 plane oriented S-W, NP2 – N-W. The type of motion along both planes – slips with uplift components, right side slip for NP1 and left side for NP2.
In accordance with USGS NEIC Мо=5.7*10**18 N*m, Mw=6.4. In accordance with Quick CMT Мо=7.26*10**18 N*m, Mw=6.5.
|
| 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 |
| 32 | 183 | 4 | 275 |
58 | 11 | 225 | 71 | 154 | 324 |
65 | 21 | NEIC | | 31 | 196 | 13 | 98 |
55 | 348 | 232 | 58 | 166 | 330 |
78 | 33 | Quick CMT | |
| NEIC - National Earthquakes Information Center of US Geological Service |
| Quick CMT - Quick CMT catalog |
Figure 6 | 
Figure 7 |
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