Information message about destructive earthquake in Northern Sumatra, Indonesia, July 2, 2013 |
| The destructive earthquake with M=6.3 has occurred in Northern Sumatra, Indonesia on July 2, 2013 at 07:37 GMT (11:37 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 15 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 48 stations, accurate processing - with data 55 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Taijon (∆ 42.3º), Ulaanbaatar(∆ 43.9º), Talaya (∆ 47.2º), Kurchatov (∆ 48.3º), Borovoe (∆ 52.8º). Fig. 2 presents fragments of records obtained from digital stations Arti (∆ 59.7º), Kislovodsk (∆ 61.3º), Obninsk (∆ 69.3º), Petropavlovsk (∆ 69.7º), Tiksi (∆ 69.8º).
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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 |
07-37-01.2 |
4.73 |
96.6 |
10 |
55 |
6.3/31 | 6.2/29 | 8.5-9 | 73 | IPC GS RAS (Accurate) | | 2 |
07-37-01.0 |
4.72 |
96.59 |
10 |
48 |
6.3/29 | 6.2/23 | 8.5-9 | 73 | IPC GS RAS (Preliminary) | | 3 |
07-37-03.5 |
4.72 |
96.574 |
10 |
297 |
Mw 6.1 | | | 35 | CSEM | | 4 |
07-37-02.9 |
4.698 |
96.687 |
10 |
87 |
Mw 6.1 | | | 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 Northern Sumatra, Indonesia, at the depth of 10 km, 167 km SE of Banda-Aceh, Indonesia, 263 km NW of Medan, Indonesia. |
Figure 3 |
|
| Aftershock |
| GS RAS registered 2 aftershocks with М≥5.2 within 8 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 |
| 20132441 | 2013-07-02 13:55:38.0 | 4.67 | 96.81 | 20 | 27 | - | 5.3/ 19 | 5-5.5 | Northern Sumatera, Indonesia | | 20132442 | 2013-07-02 15:36:45.0 | 4.67 | 96.72 | 20 | 23 | - | 5.2/ 11 | 4.5-5 | Northern Sumatera, Indonesia | |
| Macroseismic manifestations |
| According to ITAR-TASS 29 persons were killed as a result of this earthquake. National agency of emergency situations of Indonesia also reported about 400 suffered persons. Nearly 1500 hoses were destroyed. At this time army, police and volunteers disassemble debris in the influenced regions of Sumatra. The most destructions were registered in the region located 320 km of province capital Banda-Aceh. Nearly 90% of houses were destroyed in Blanmachung village located in the Central Aceh Regon.
Fig. 4 presents USGS Community Internet Intensity Map obtained from site of US GS NEIC, based on 28 responses in 11 cities. |
Figure 4 |
|
| Historical records |
| Indonesia — one of the most seismic active regions of the world. On December 26, 2004 the strongest earthquake with M=8.8 has occurred near north-western coast of Sumatra. It cauased the tsunami which killed hundreds of thousands of people in 12 Indian Ocean contries. |
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solution of the origin was calculated in IPC GS RS with signs of initial arrivals of P waves at 75 stations, including 43 stations which registered the waves of compression (minus signs) and 32 stations which registered the waves of extension (plus signs). These stations are located in the interval of epicentral distances of 3–97º and are evenly dispersed along the azimuths. Focal mechanism solution in stereographic projection at the lower hemisphere is presented at fig. 5, elements of this solution are presented in table 2. Fig. 6 and 7 present mechanisms obtained in USGS with USGS Centroid Moment Solution and in Quick CMT Catalog, USA with CMT technique. All solutions are close.
This earthquake occurred under the action of close in value compression stresses oriented north–south, and extension stresses oriented west-east. One nodal plane NP1 is almost vertical in north-east direction (DP=77-90º), another plane NP2 is also steeply deeping (DP=60-78º) in direction north-east – south-west. The type of motion in all solutions is strike slip – for NP1 left side and for NP2 right side.
Seismic moment of this earthquake obtained in IPC GS RAS with spectra of Р waves at «Talaya» station (∆47.17) makes Мо=2.3*10**18 N*m, Mw=6.2. In accordance with USGS NEIC Мо=1.6*10**18 N*m, Mw=6.1, in accordance with Quick CMT Мо=1.79*10**18 N*m, Mw=6.1.
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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 |
| 20 | 248 | 16 | 152 |
64 | 27 | 21 | 87 | 26 | 289 |
64 | 177 | IPC GS RAS | | 21 | 264 | 20 | 166 |
60 | 35 | 35 | 90 | 30 | 305 |
60 | 30 | NEIC | | 1 | 261 | 18 | 351 |
72 | 167 | 34 | 77 | -12 | 127 |
78 | -12 | 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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