Information message about the catastrophic earthquake in Nepal, April 25, 2015 |
| The catastrophic earthquake M=7.9 has occurred on April 25, 2015 at 06:11 GMT (09:11 Moscow time) in Nepal, resulting in human casualties and destruction. |
| 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 10 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 34 stations, accurate processing - with data 57 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Ala-Archa (∆ 16.7º), Pallekele (∆ 21.1º), Jazator (∆ 21.6º), Arti (∆ 33.9º), Belogornoye (∆ 36.7º). Fig. 2 presents fragments of records obtained from digital stations Khabaz (∆ 36.9º), Kislovodsk (∆ 37.1º), Kirov (∆ 39º), Norilsk (∆ 41.2º), Obninsk (∆ 43.8º). |
Figure 1
| 
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 |
06-11-24.1 |
28.18 |
84.78 |
13 |
66 |
7.9/32 | 7.3/36 | 10.5-11 | 62 | IPC GS RAS (Accurate) | | 2 |
06-11-25.9 |
28.17 |
84.8 |
10 |
34 |
| 6.8/18 | 9.5-10 | 62 | IPC GS RAS (Preliminary) | | 3 |
06-11-26.3 |
28.28 |
84.79 |
10 |
801 |
Mw 7.8 | | | 26 | CSEM | | 4 |
06-11-26.3 |
28.15 |
84.71 |
15 |
108 |
Mw 7.8 | | | 35 | 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, its origin was located on the territory of Nepal, at the depth of 13 km, 75 km N-W of Kathmandu - capital of Nepal, 80 km E of Pokhara and 369 km N-E of Varanasi, India. |
Figure 3 |
|
| Aftershock |
| GS RAS registered 20 aftershocks М>=4.6 within the day after the main shock. The strong aftershock М=7.0 has occurred in 25 hours 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 |
| 20151415 | 2015-04-25 06:37:58.0 | 27.94 | 85.81 | 10 | 14 | - | 5.2/ 10 | 5.5-6 | Nepal | | 20151407 | 2015-04-25 06:45:19.0 | 28.14 | 84.89 | 15 | 42 | 6.8/ 27 | 6.8/ 27 | 9 | Nepal | | 20151417 | 2015-04-25 06:56:31.0 | 27.75 | 85.76 | 10 | 31 | - | 5.8/ 20 | 7-7.5 | Nepal | | 20151418 | 2015-04-25 07:07:57.0 | 27.68 | 85.9 | 10 | 40 | - | 5.2/ 21 | 5.5-6 | Nepal | | 20151408 | 2015-04-25 07:46:59.0 | 27.84 | 85.64 | 10 | 45 | - | 5.2/ 28 | 5.5-6 | Nepal | | 20151419 | 2015-04-25 08:16:58.0 | 27.79 | 85.82 | 10 | 34 | - | 5.1/ 17 | 5.5-6 | Nepal | | 20151421 | 2015-04-25 08:29:22.0 | 27.98 | 84.73 | 10 | 42 | - | 5.2/ 22 | 5.5-6 | Nepal-India border region | | 20151409 | 2015-04-25 08:55:55.0 | 27.68 | 85.67 | 10 | 49 | - | 5.6/ 28 | 6.5-7 | Nepal | | 20151410 | 2015-04-25 09:17:00.0 | 28.36 | 87.41 | 10 | 51 | - | 5.7/ 30 | 7-7.5 | Xizang | | 20151411 | 2015-04-25 09:30:27.0 | 27.88 | 85.55 | 10 | 39 | - | 5.4/ 20 | 6-6.5 | Nepal | | 20151412 | 2015-04-25 10:23:16.0 | 27.71 | 85.7 | 10 | 16 | - | 4.6/ 10 | 4.5 | Nepal | | 20151414 | 2015-04-25 10:40:33.0 | 27.55 | 85.94 | 10 | 31 | - | 4.9/ 25 | 5-5.5 | Nepal | | 20151416 | 2015-04-25 12:44:03.0 | 28.1 | 84.65 | 10 | 38 | - | 5.2/ 22 | 5.5-6 | Nepal | | 20151422 | 2015-04-25 16:27:20.0 | 27.91 | 85.66 | 10 | 37 | - | 5.1/ 23 | 5.5-6 | Nepal | | 20151425 | 2015-04-25 17:42:50.0 | 28.31 | 85.95 | 10 | 33 | - | 5.4/ 21 | 6-6.5 | Nepal | | 20151428 | 2015-04-25 21:07:16.0 | 27.75 | 85.8 | 10 | 32 | - | 5.0/ 18 | 5-5.5 | Nepal | | 20151430 | 2015-04-25 23:16:13.0 | 27.83 | 84.97 | 10 | 46 | - | 5.6/ 27 | 6.5-7 | Nepal-India border region | | 20151431 | 2015-04-25 23:41:51.0 | 27.59 | 86.1 | 10 | 21 | - | 4.7/ 13 | 4.5-5 | Nepal | | 20151435 | 2015-04-26 02:48:37.0 | 28.17 | 84.58 | 10 | 21 | - | 4.8/ 14 | 4.5-5 | Nepal | | 20151436 | 2015-04-26 04:58:38.0 | 27.9 | 84.72 | 10 | 20 | - | 4.6/ 13 | 4.5 | Nepal-India border region | | 20151438 | 2015-04-26 07:09:06.0 | 27.78 | 86.09 | 10 | 66 | 7.0/ 28 | 6.6/ 35 | 10 | Nepal | |
| Macroseismic manifestations |
| According to ITAR-TASS, as a result of the earthquake that occurred in Nepal on April 25, died 7557 person, more than 14500 damaged, destroyed many buildings in the capital city of Nepal Kathmandu. Significant damage caused to the historic city center.
Destroyed erected in 1832 62-meter high observation tower Dharahara, listed as a world heritage site by UNESCO(Fig.4). The Earthquake triggered an avalanche in the Himalayas, on mount Everest killed 80 climbers. The earthquake was felt in neighboring countries, in China, India, Pakistan, Bangladesh. Here the death toll has exceeded 100 people. Salvation is connected rescuers from China, USA, Canada, Australia, Japan, USA and Sri Lanka. EMERCOM of Russia has sent to Nepal two aircraft with rescuers.The country declared three days of national mourning.
Fig. 4 was obtained from USGS NEIC , it presents USGS Community Interenet Intensity Map based on 1047 responses in 278 cities. |
Figure 4 | 
Figure 5 |
|
| Historical records |
| Over the past 100 years, there were only 4 historical events M>6 in a radius of 250 km from the current earthquake. Latest M=6.9 occurred in August 1988, 240 km to the SE, it has caused the deaths of 1,500 people. The strongest M=8, known as the Nepal-Bihar, occurred in the same place in 1934, as a result of this earthquake killed more than 10 thousand people. |
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solution was obtained in IPC GS RAS with signs of initial arrivals of P waves at 46 stations, including 38 stations which registered the waves of compression (plus signs) and 8 stations which registered tensile waves (minus signs).
Focal mechanism solution in stereographical projection at the lower hemisphere is presented at fig. 6, elements of mechanism are presented in table 2. Fig. 7, 8 present solutions obtained in USGS NEIC with W-phase Moment Tensor (Mww) technique and in Quick CMT Center obtained with CMT technique. Elements of these mechanisms are also presented in table 2. All solutions obtained in different centers are almost identical.
The motion has occurred under the action of close in value compression and tensile stresses, oriented to the North and South respectively. Nodal plane NP1 strikes to the east (STK=95-97º), NP2 - strikes to the west (STK=281-295º). NP1 plane is vertical (DP=71-83º), NP2 - flat (DP=7-19º). The type of motion along vertical plane – reverse fault with left lateral slip components, along horizontal plane – overthrust with right lateral slip components.
Seismic moment of this earthquake was obtained in IPC GS RAS with spectra of Р waves registered at station «Obninsk» (∆43.8º), Мо=3.87*10**20 N*m, Mw=7.7. According to NEIC Mo=5,45*10**20 N*m, Mw=7.8, according to СМТ Mo=7.76*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 |
| 64 | 6 | 26 | 189 |
1 | 96 | 98 | 71 | 89 | 281 |
19 | 94 | IPC GS RAS | | 55 | 2 | 34 | 190 |
3 | 97 | 97 | 80 | 87 | 295 |
11 | 108 | NEIC | | 52 | 2 | 38 | 187 |
2 | 95 | 95 | 83 | 88 | 293 |
7 | 108 | 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 |
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