Information message about earthquake of August 17, 1999 in Turkey |
| On August 17 1999 at 4 hours Moscow time (00 hours GMT) catastrophic earthquake in Turkey has taken place. It was one of the strongest earthquakes in Turkey in this century. |
| Parameters of this earthquake have been determined by the Alert Service (AS) of Information Processing Center (IPC) in Geophysical Survey of RAS in Obninsk with station data from digital and analog seismic stations of Russia, countries of CIS and abroad. Initial summary processing of this earthquake has been executed on data from 12 stations and following processing on data from 27 satations. |
| 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 |
00-01-44.30 |
41 |
30 |
33 |
12 |
7.50/4 | 6.60/1 | 8.5-9 | | IPC GS RAS (Initial) | | 2 |
00-01-38.70 |
41 |
30 |
15 |
27 |
7.6/6 | 7.0/3 | 9-10 | | IPC GS RAS (Improved) | | 3 |
00-01-52.20 |
41 |
29 |
88 |
162 |
7.5-7.8 | 5.8-6.7 | | | CSEM (Initial) | | 4 |
00-01-37.00 |
40 |
29 |
6 |
216 |
| 4.4-6.7 | | | CSEM (Improved) | | 5 |
00-01-38.60 |
40 |
29 |
|
85 |
7.8 | | | | NEIC | | 6 |
00-01-37.99 |
40 |
30 |
|
21 |
/1 | 5.5/13 | | | pIDC | | 7 |
00-01-37.60 |
40 |
29 |
17 |
|
| | | | KOERI | |
| 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 |
| pIDC - Prototype International Data Center |
| KOERI - Kandilli Observatory and Earthquake Research Institute, Turkey |
| Epicenter |
| Hypocenter location is shown on figure 1 according to the information of AS.
Hypocenter of this event was located closely to industrial town Izmit, which is situated in 80 km to the East from Istanbul. |
Figure 1 |
|
| Macroseismic manifestations |
| According to the information of ITAR TASS there is a huge destruction and numerous victims. A few dozens of high living building have fallen simultaneously. At oil refining plant in Izmit there was a fire. Istanbul city was left without electricity (after automatic switch off in electric power supply circuit). From data of ITAR TASS at 18 hours of Moscow time on 17.08.1999 nearly 3500 people were lost and 16000 thousand wounded. The earthquake was felt in towns of Russia, Moldavia and Ukraine: in Anapa, Kishinev, Semfiropol and all around Black sea coast of Crimea with intensity 2-3 MSK.
|
| Historical records |
| From data of the NORTHERN EURASIA CATALOAG OF EARTHQUAKES (only russian version) from ancient times till 1990 and from data of SEISMOLOGICAL BULLETIN OF CEME GS RAS from 1955 up now there were no strong destructive earthquakes in this area, while earlier such earthquakes (with intensity in hypocenter 7 and more MSK) have happened here, their parameters are given in table 2. |
| Таблица 2 | | NN | Year | Month | Day | Time | Latitude N
degr. | Longitude Е
degr. | Depth | Ms | Io,
number |
| 1 | 1672 | 05 | 25 | | 41.00 | 30.00 | 14 | 6.1 | 8-9 |
| 2 | 1719 | 05 | 25 | 12ч | 40.80 | 29.40 | 14 | 6.1 | 8-9 |
| 3 | 1878 | 04 | 19 | | 40.70 | 30.00 | 17 | 6.5 | 8-9 |
| 4 | 1943 | 06 | 20 | 15-32-54.0 | 40.80 | 30.50 | 18 | 6.5 | 8-8 |
| 5 | 1957 | 05 | 26 | 06-33-35.0 | 40.70 | 31.00 | 100 | 7.1 | 10 |
| 6 | 1957 | 05 | 26 | 09-36-39.0 | 40.8 | 30.8 | 10 | 6.0 | 8-9 |
| 7 | 1957 | 05 | 27 | 11-01-27.0 | 40.70 | 31.00 | 36 | 6.2 | 7-7 |
| 8 | 1967 | 07 | 22 | 16-56-58.0 | 40.67 | 30.69 | 9 | 7.1 | 10 |
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism of the earthquake 17.08.1999 was calculated in IPC GS RAS after firs signs of P-wave arrivals at 38 stations, which are located in the interval of hypocenter distances of 6.2-93.5 degrees with quite uniform distribution between azimuths from 14 to 359 degrees. Location of nodal planes in projection of lower hemisphere is given on figure 2 and in table 3.
The solution from Harvard Center (USA) by method of tensor moment centeroid (TMC) can be found there too. These solutions are almost the same. Focal mechanism is almost the pure thrust along both nodal planes. Both nodal planes have a steep depth, one of them is oriented directly to the north-south, while the other to the east-west direction. Compression and expansion axes are practically horizontal, angle of dip is not more than 9 degrees.
Seismic moment Мо of the earthquake is determined from spectrum of P-wave, registered at seismic station ARU, which is located at distance of 23 degrees from hypocenter. The value of seismic moment made Mo= 1.0 E 20 n* m, magnitude of moment Mw=7.3. According to Harvard Center these values are as Mo=2.1 E 20 n* m, Mw=7.5.
|
| 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 |
| 7 | 232 | 9 | 141 |
78 | 360 | 277 | 78 | -179 | 186 |
89 | -12 | IPC GS RAS | | 5 | 224 | 4 | 133 |
84 | 358 | 268 | 84 | 180 | 178 |
90 | -6 | HARVARD | |
| IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences |
| HARVARD - Harvard Geophysical Center (USA) |
Figure 2 |
|
