Information message about earthquake on September 7, 1999 in Greece |
| On September 7 1999 at 15:56 Moscow time (11:56 GMT) destructive earthquake has happened near capital of Greece Athens. |
| Parameters of this earthquake have been determined by Alert Service (AS) of Information Processing Center (IPC) of Geophysical Survey of RAN in Obninsk with use of station data obtained from digital and analog seismic stations of Russia, countries of CIS and from abroad. |
| Preliminary processing has been done with data from 17 stations, accurate processing - with data 30 stations. |
| Figures 1-2 present records from digital stations, which were obtained by IPC in a close to real time mode.
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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: |
| Note: NOA - National observatory of Geodynamics Institute, Athens, Greece (Information of NOA was downloaded from Web-server). |
| 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 |
11-56-49.50 |
38 |
23 |
33 |
17 |
5.90/11 | 5.80/7 | 6.5 | | IPC GS RAS (preliminary) | | 2 |
11-56-50.6 |
38 |
23 |
15 |
30 |
5.9/14 | 5.8/7 | 8 | | IPC GS RAS (amended) | | 3 |
11-56-50.4 |
38 |
23 |
10 |
12 |
5.9 | | | | IPC GS RAS (NOA) | | 4 |
11-56-48.8 |
23 |
29 |
5 |
270 |
| 4.8-5.8 | | | CSEM (preliminary) | | 5 |
11-56-50.3 |
23 |
29 |
10 |
|
| 5.3-5.8 | | | CSEM (amended) | | 6 |
11-56-50.3 |
38 |
23 |
|
85 |
| 5.8 | | | NEIC | | 7 |
11-56-51.9 |
38 |
23 |
13 |
23 |
| 5.5/13 | | | pIDC | |
| 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 |
| Epicenter |
| According to data of AS location of this earthquake's hypocenter is shown on the map (size of file 75 kB), it contains information about main tectonic structures of Mediterranean Alpine seismic belt (Nafi TOKMOZ) http://tanasi.gg.utk.edu/izmit.htm, http://geophysics.gg.utk.edu/izmit/earthquake.htm (obtained from Internet). Here the location of earthquake in Turkey on August 17, 1999 is shown too.
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| Macroseismic manifestations |
| Hypocenter of this destructive earthquake was located 20 km to the north-west from capital Athens. According to the information of ITAR TASS 36 people have been lost (including those from sheer heart attack) on September 8 at 16 hours Moscow time. Most destruction was observed in capital area Attika, where 100 buildings were destroyed, 400 victims were delivered to hospital. 120 people were found under debris.
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| Focal mechanism and seismic moment of the earthquake |
| IPC GS RAS received information on parameters of origin's focal mechanism for earthquake in Greece from Harvard Center USA, which were obtained from centroid moment of tensor method (CMT). According to solution of СМТ the motions along nodal planes of close to latitude directions and deep depth are presented by thrusts. Earthquake's origin occurred under dominating action of expanding strength. Locations of nodal planes in projection of lower hemisphere are shown on figure 3. Elements of origin's focal mechanism are presented in table 3.
Seismic moment Мо of the earthquake has been determined from spectra of Р-waves, which were registered at two seismic stations: Arti (ARU) and Talaya (TLY) located at distances of 29.5 and 55.6 degrees from origin place respectively. Average value of Мо made 1.9 Е 18 n*m (1.9* 10**25 D-CM). The value of moment magnitude has been determined as Mw =6.1.
Seismic moment Мо of the earthquake has been determined from spectra of Р-waves, which were registered at two seismic stations: Arti (ARU) and Talaya (TLY) located at distances of 29.5 and 55.6 degrees from origin place respectively. Average value of Мо made 1.9 Е 18 n*m (1.9* 10**25 D-CM). The value of moment magnitude has been determined as Mw =6.1.
|
| 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 |
| 1 | 12 | 78 | 108 |
12 | 282 | 114 | 45 | -73 | 271 |
47 | -106 | HARVARD | |
| HARVARD - Harvard Geophysical Center (USA) |
Figure 3 |
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