Information message about sensitive earthquake in Romania, October 6, 2013 |
| The sensitive earthquake with magnitude M=5.5 has occurred in Romania on October 6, 2013 at 01:37 GMT (05:37 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 27 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 32 stations, accurate processing - with data 54 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Isparta (∆ 8.5º), Kaliningrad (∆ 9.7º), Storozhevoye (∆ 10.1º), Obninsk (∆ 11.4º), Kislovodsk (∆ 11.7º). Fig. 2 presents fragments of records obtained from digital stations Vasula (∆ 12.7º), Pulkovo (∆ 14.2º), Garni (∆ 14.5º), Arti (∆ 22.6º), Ala-Archa (∆ 34.2º). |
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 |
01-37-19.2 |
45.75 |
26.46 |
130 |
54 |
| 5.5/19 | 4-5 | 103 | IPC GS RAS (Accurate) | | 2 |
01-37-19.2 |
45.68 |
26.5 |
130 |
32 |
| 5.6/17 | 4-5 | 103 | IPC GS RAS (Preliminary) | | 3 |
01-37-20.0 |
45.64 |
26.69 |
133 |
155 |
| 5.4 | | 27 | CSEM | | 4 |
01-37-21.7 |
45.671 |
26.547 |
135.82 |
165 |
| 5.3 | | 20 | NEIC | | 5 |
01-37-21.7 |
45.642 |
26.688 |
133.6 |
18 |
ML 5.5 | | | 92 | NIEP | | 6 |
01-37-21.4 |
45.73 |
26.53 |
128 |
342 |
| 5.4/310 | | | GFZ | |
| 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 |
| NIEP - National Institute for Earth Physics, Romania |
| GFZ - German Research Center for Geosciences |
| Epicenter |
| Fig. 3 presents with red star epicenter of this earthquake which origin was located in Romania at the depth of 130 km, 67 km E of Brasov, 149 km N-N-E of Bucharest, the capital of Romania, and 229 km W-S-W of Kishinev, the capital of Moldova. |
Figure 3 |
|
| Aftershock |
| Some increased seismic activity was registered by a few seismological centers not long before this earthquake. GSRAS registered 6 weak shocks with magnitudes from 3 to 4.2 and the depth of 5-10 km within a week before the earthquake. |
| Macroseismic manifestations |
| This earthquake was felt in Romania and neighboring countries: Bulgaria, Moldova and Ukraine. In southern regions of Ukraine it was felt in Odessa, Nikolaev, Kherson and Crimea. In Odessa region it was felt most of all. «The shocks were felt in Izmail, Bolgradsk, Kilijsk and Renijsk areas of Odessa region. There were no victims or injured persons." ("Economics news" )
According to GS RAS this earthquake was felt in Kishinev with intensity 4-5, in Tiraspol with intensity 3 and in Odessa with intensity 2-3.
Fig. 4 presents USGS Community Internet Intensity Map obtained from site of USGS NEIC , based on 199 responses in 66 cities. |
Figure 4 |
|
| Historical records |
| The last strong earthquake in Romania was registered on October 27, 2004 M=6.1 at the depth of 90 km, 31 km E-N-E of the reported here earthquake. After the destructive earthquake which occurred on November 10, 1940 in the area of Vrancei M=7.3 nearly 1000 persons were killed and nearly 1500 persons were killed on March 4, 1977 after the earthquake M=7.4. These earthquakes as well as the earthquake on August 30, 1986 with M=7.1 were felt in Moscow at the ground floors of the buildings with intensity 4 and at 14-18 floors of skyscrapers with intensity 6, and in some cases with intensity 7 and they caused small cracks in walls and ceilings. The less intensive Vrancei earthquakes which also caused oscillation of upper floors of skyscrapers in Moscow had intensities 3-4, they were registered on May 30 (М=6.7) and May 31 (М=6.1) of 1990. [Ulomov V.I., 2007]. The origins of all these earthquakes were located at the depths of 90-140 km. |
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solution of the origin of this earthquake was obtained in IPC GS RAS with signs of initial arrivals of P waves at 69 stations, including 34 stations which registered compression waves (plus signs) and 35 stations which registered expansion waves (minus signs). All these stations are located in the interval of epicentral distances of 1–89º and are evenly dispersed along the azimuths. Focal mechanism solution of the origin in stereographic projection at the lower hemisphere is shown at figure 5, elements of this mechanism are presented in table 2. Figures 6, 7 present focal mechanisms obtained in USGS NEIC and Quick CMT Catalog, USA. All solutions are almost identical. the earthquake has occurred under stresses of compression oriented north-west and under stresses of extension oriented south-east. Both nodal planes NP1 and NP2 in all solutions have nearly the same declination (DP=32-58º) and are oriented north-east (STK=40-43º) – south-west (STK=225-228º). The type of motion along both planes – thrust fault («pure» in IPC GS RAS solution) and in case of USGS NEIC and Quick CMT Catalog – with slip components (left side for NP1 and right side for NP2).
Seismic moment of the earthquake was obtained in IPC GS RAS with spectra of Р waves registered at «Talaya» station (∆49.07º), Мо=2.7*10**17 N*m, Mw=5.6, according to USGS NEIC – Мо=1.27*10**17 N*m, Mw=5.3, according to Quick CMT - Мо=1.25*10**17 N*m, Mw=5.3. |
| 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 |
| 77 | 140 | 13 | 315 |
1 | 45 | 43 | 32 | 88 | 226 |
58 | 91 | IPC GS RAS | | 81 | 160 | 8 | 315 |
4 | 45 | 40 | 37 | 84 | 228 |
53 | 95 | NEIC | | 81 | 160 | 8 | 315 |
4 | 45 | 40 | 37 | 84 | 228 |
53 | 95 | 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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