Information message about destructive earthquake in Nepal, May 12, 2015 |
| The destructive earthquake M=7.5 has occurred on May 12, 2015 at 07:05 GMT (10:05 Moscow time) in Nepal, it caused victims and destructions. This is the strongest modern aftechock from catastrophic earthquake of April 25 with М=7.9 known as Gorkha earthquake. |
| 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 36 stations, accurate processing - with data 67 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Ala-Archa (∆ 17.6º), Pallekele (∆ 21.1º), Jazator(∆ 21.9º), Ulaanbaatar (∆ 25.8º), Borovoe (∆ 27.8º). Fig. 2 presents fragments of records obtained from digital stations Arti (∆ 34.7º), Garni (∆ 36.2º), Nalchik (∆ 37.6º), Kislovodsk (∆ 38.3º), Obninsk (∆ 44.8º). |
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 |
07-05-17.3 |
27.82 |
86.21 |
15 |
67 |
7.5/26 | 6.9/37 | 10-10.5 | 65 | IPC GS RAS (Accurate) | | 2 |
07-05-19.2 |
28.04 |
86.16 |
10 |
32 |
| 6.6/16 | 9-9.5 | | IPC GS RAS (Preliminary) | | 3 |
07-05-19.0 |
27.89 |
86.17 |
10 |
743 |
Mw 7.3 | | | 18 | CSEM | | 4 |
07-05-19.0 |
27.84 |
86.08 |
15 |
214 |
Mw 7.3 | | | 27 | 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 the earthquake on April 25 М=7.9, 140 km E-S-E of yellow star which is epicenter of the aftershock on May 12 М=7.5. The origin of this aftershock was located on the territory of Nepal at the depth of 15 km, 55 km N-N-E of Ramechhap and 89 km E-N-E of Kathmandu, the Capital City of Nepal. |
Figure 3 |
|
| Aftershock |
| GS RAS registered another 7 aftershocks M>=4.5 within 2 hours after this shock М=7.5. |
| 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 |
| 20151682 | 2015-05-12 07:17:19.0 | 27.75 | 86.2 | 15 | 37 | - | 5.3/ 29 | 5.5 | Nepal | | 20151684 | 2015-05-12 07:34:21.0 | 27.67 | 86.28 | 15 | 20 | - | 5.4/ 14 | 5.5-6 | Nepal | | 20151685 | 2015-05-12 07:36:51.0 | 27.52 | 86.15 | 15 | 60 | - | 6.4/ 34 | 8-8.5 | Nepal | | 20151686 | 2015-05-12 08:06:07.0 | 27.84 | 86.05 | 15 | 18 | - | 5.2/ 13 | 5-5.5 | Nepal | | 20151687 | 2015-05-12 08:13:54.0 | 27.96 | 85.9 | 15 | 34 | - | 5.2/ 25 | 5-5.5 | Nepal | | 20151689 | 2015-05-12 08:21:10.0 | 27.8 | 86.1 | 15 | 28 | - | 5.3/ 22 | 5.5 | Nepal | | 20151688 | 2015-05-12 09:02:09.0 | 27.78 | 86.01 | 15 | 20 | - | 4.5/ 11 | 3.5-4 | Nepal | |
| Macroseismic manifestations |
| From RIA-Novosti this earthquake has killed 36 and injured 1117 persons.
Fig. 4 was obtained from USGS NEIC , it presents USGS Community Internet Intensity Map based on 777 responses in 223 cities. |
Figure 4 |
|
| Focal mechanism and seismic moment of the earthquake |
| The focal mechanism of the earthquake was obtained in IPC GS RAS by the signs of the first arrivals of p-waves on 78 stations, including 58 registered waves of compression (plus sign) and 20 stations registered tensile waves (minus sign).The stations are located in the interval of epicentral distances of 0–96º in the azimuth Az target=16-348º. The focal mechanism in stereographic projection at the lower hemisphere is shown in Fig. 5, elements of the mechanism are presented in table.2. In Fig. 6, 7 the mechanisms of the hearth according to the National center of information about earthquakes from the U.S. Geological survey, USGS NEIC on the basis of the W-phase Moment Tensor (Mww) and according to the center Quick CMT by the method of moment tensor centroid. The elements of the mechanism are also presented in table.2. Solutions according to different centres are similar. The motion occurred under the action of close in magnitude of compressive and tensile stresses directed to the South (Az=190-207º) and North (Az=9-356º), respectively. The strike of the nodal plane NP1 – East-South-West (STK=94-107º), NP2 – North-West (STK=303-347º). Plane NP1 vertical (DP=82-84º), NP2 is flat (DP=9-12ºc). The type of motion along vertical plane - overthrust with left lateral slip, along horizontal plane – transverse thrust with right lateral slip.
Seismic moment of this earthquake was obtained in IPC GS RAS with Р-wave spectra registered at «Obninsk» station (∆44.8º), Мо=1.35*10**20 N*m, Mw=7.4. According to USGS NEIC – Mo=0.99*10**20 N*m, Mw=7.3, according to CMT – Мо=0.9*10**20 N*m, Mw=7.2.
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| 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 |
| 50 | 6 | 38 | 207 |
10 | 109 | 107 | 84 | 80 | 347 |
12 | 149 | IPC GS RAS | | 53 | 9 | 37 | 195 |
3 | 103 | 102 | 82 | 87 | 303 |
9 | 110 | NEIC | | 53 | 356 | 36 | 190 |
7 | 95 | 94 | 81 | 83 | 312 |
11 | 127 | 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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