Information message about destructive earthquake in the Lake Victoria region, Tanzania-Uganda border, September 10, 2016 |
| The devastating earthquake M=5.3 occurred on September 10, 2016 at 12:27 GMT (15:27 Moscow time) in the Lake Victoria region, Tanzania-Uganda border. |
| 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 16 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 15 stations, accurate processing - with data 46 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Kilima Mbogo (∆ 5.7º), Apeiranthos of Naxos (∆ 38.3º), Isparta (∆ 38.7º), Keskin Array Point (∆ 40.6º), Garni (∆ 42.6º). Fig. 2 presents fragments of records obtained from digital stations Khabaz (∆ 45.7º), Kislovodsk (∆ 45.9º), Malin Array Point (∆ 51.6º), Belogornoye (∆ 54.9º), Arti (∆ 61.3º). |
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 |
12-27-26.1 |
-1.01 |
31.58 |
10 |
46 |
5.3/18 | 5.8/30 | 7-7.5 | 157 | IPC GS RAS (Accurate) | | 2 |
12-27-40.4 |
-0.97 |
31.55 |
100 |
15 |
| 5.8/10 | 3.5-4 | | IPC GS RAS (Preliminary) | | 3 |
12-27-28.6 |
-1.06 |
31.55 |
10 |
369 |
| 5.7 | | 32 | CSEM | | 4 |
12-27-33.1 |
-1.03 |
31.56 |
40 |
112 |
Mw 5.9 | 5.7 | | 30 | 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 the epicenter of this earthquake, its origin was located in the Lake Victoria region, Tanzania-Uganda border, at a depth of 10 km, 42 km N-W of Bukoba, Tanzania, 77 km S-S-W of Masaki and 11 km E-S-E of Mbarara, Uganda. |
Figure 3 |
|
| Macroseismic manifestations |
| According to ITAR-TASS 16 persons were killed and 253 injured. Kagera province in Tanzania was the most affected area, as a result of this earthquake 840 buildings, including 44 public institutions were destroyed.
Fig. 4 was obtained from USGS NEIC , it presents USGS Community Internet Intensity Map based on 177 responces in 51 cities. |
Figure 4 |
|
| Historical records |
| The origin is located the East African Rift System. GS RAS registered earthquake 595 km S-S-W of this one on December 5, 2005 There are known quite rare tangible earthquakes. That earthquake was felt in the area of Lake Tanganyika M=6.9, it was felt in 6 countries, including the Democratic Republic of the Congo and Tanzania. The devastating earthquake occurred in Mozambique on February 22, 2006 М=7.3, it became the strongest for South Africa over the past hundred years. The last earthquake has occurred on November 20, 2012 M=5, it was registered 157 km W of the reported earthquake. |
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solution of the origin was calculated in IPC GS RAS with signs of initial arrivals of P waves at 30 stations, including 22 stations which registered compression waves (plus signs) and 8 stations which registered tensile waves (minus signs). These stations are located in the interval of epicentral distances 1º–86º and azimuth sector Az=3-347º. Focal mechanism solution of the origin in stereographic projection at the lower hemesphere obtained with IPC GS RAS data is presented in figure 5. Focal mechanism solution obtained in USGS NEIC with W-phase Moment Tensor (Mww) technique is presented in figure 6. Element of that mechanism are given in table 2.
This earthquake has occurred under prevailing action of tensile stress (Pl=6-20º, Azm=12-161º), the compression stress was oriented to the west (Azm=257-272º). Nodal planes NP1 and NP2 are nearly vertical (DP=57º-87º), NP1 strikes N-E (STK=36-53º); NP2 strikes to the west (STK=290-321º). The type of motion – slip with fault components, with right latteral slip component for NP1 and left latteral slip component for NP2.
The seismic moment of the earthquake was obtained in IPC GS RAS from spectra of Р waves registered at «Kislovodsk» station (∆45.87º), Мо=8.2*10**17 N*m, Mw=5.9. According to USGS NEIC – Mo=8.227*10**17 N*m, Mw=5.9. |
| 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 |
| 20 | 12 | 25 | 272 |
57 | 136 | 53 | 57 | -176 | 321 |
87 | -33 | IPC GS RAS | | 6 | 161 | 42 | 257 |
48 | 64 | 36 | 67 | -144 | 290 |
57 | -28 | NEIC | |
| IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences |
| NEIC - National Earthquakes Information Center of US Geological Service |
Figure 5 | 
Figure 6 |
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