Red markers on the map show the epicenters of the earthquakes, whose origins were located in the northern part of Greece, at a depth of 10 km. The epicenter of the first shock was located 30 km W-NW of Larissa, 35 km NE of Trikala and 240 km NW of Athens, the capital of Greece. The epicenter of the second shock was located 18 km NW of the first one.
|
Time in origin (GMT) |
Latitude, degree |
Longitude, degree |
Depth, km |
Stations number |
Ms/N |
mb/N |
I0 (calculated) |
GAP |
Center |
1
|
18:38:23.6
|
39.86 |
22.01 |
33.0 |
14
|
|
6.0/10 |
6-6.5 |
|
GS RAS(Preliminary) Federal research center, Geophysical survey of Russian Academy of Sciences
|
2
|
18:38:19.4
|
39.77 |
22.1 |
11.0 |
45
|
|
5.7 |
|
63
|
CSEM European - Mediterranean seismological center
|
3
|
18:38:19.6
|
39.75 |
22.13 |
10.0 |
108
|
|
5.6/56 |
|
20
|
NEIC National Earthquakes Information Center of US Geological Service
|
4
|
10:16:09.0
|
39.73 |
22.09 |
10.0 |
59
|
6.1/44 |
6.2/31 |
8.5-9 |
187
|
GS RAS(Verified) Federal research center, Geophysical survey of Russian Academy of Sciences
|
5
|
10:16:14.7
|
39.87 |
21.94 |
33.0 |
12
|
|
6.0/10 |
6-6.5 |
|
GS RAS(Preliminary) Federal research center, Geophysical survey of Russian Academy of Sciences
|
6
|
10:16:08.3
|
39.75 |
22.2 |
8.0 |
49
|
Mw 6.3 |
|
|
48
|
CSEM European - Mediterranean seismological center
|
7
|
10:16:10.2
|
39.76 |
22.18 |
10.0 |
129
|
Mw 6.3/81 |
6.2/121 |
|
17
|
NEIC National Earthquakes Information Center of US Geological Service
|
8
|
18:38:19.0
|
39.86 |
21.94 |
10.0 |
53
|
6.2/19 |
6.0/24 |
8.5-9 |
148
|
GS RAS(Verified) Federal research center, Geophysical survey of Russian Academy of Sciences
|
Fig. 1 presents fragments of records obtained from digital stations Apeiranthos of Naxos (∆ 3.8º), Keskin Array (∆ 8.9º), Kasperske Hory (∆ 11.2º), Anapa (∆ 12.4º), Kislovodsk (∆ 15.9º) for the first earthquake. Fig. 2 presents fragments of records obtained from digital stations Apeiranthos of Naxos (∆ 4º), Keskin Array (∆ 9º), Kasperske Hory (∆ 11º), Malin Array (∆ 12º), Shidzhatmaz (∆ 16º) for the second earthquake.
Image 1
Image 2
GS RAS registered 9 more earthquakes with a magnitude of 4.5 <= M <= 5.5 during March 3-4.
N |
Time in origin (GMT) |
Latitude, degree |
Longitude, degree |
Depth, km |
Stations number |
Ms/N |
mb/N |
I0 (calculated) |
Region |
20210914
|
03/03/2021 10:34:08.0.0 |
39.56 |
22.2 |
10.0 |
45 |
|
5.3/21 |
6-6.5 |
Greece
|
20210916
|
03/03/2021 11:19:02.0.0 |
39.69 |
22.21 |
10.0 |
14 |
|
4.6/4 |
4.5 |
Greece
|
20210917
|
03/03/2021 11:35:57.0.0 |
39.63 |
22.14 |
10.0 |
53 |
|
5.1/18 |
5.5-6 |
Greece
|
20210919
|
03/03/2021 11:45:46.0.0 |
39.69 |
22.2 |
10.0 |
47 |
|
5.5/21 |
6.5-7 |
Greece
|
20210923
|
03/03/2021 18:24:07.0.0 |
39.69 |
21.9 |
10.0 |
56 |
|
5.5/22 |
6.5-7 |
Greece
|
20210924
|
03/03/2021 21:00:55.0.0 |
39.74 |
22.02 |
10.0 |
22 |
|
4.5/10 |
4-4.5 |
Greece
|
20210931
|
04/03/2021 09:36:16.0.0 |
39.8 |
22.09 |
10.0 |
36 |
|
4.8/19 |
4.5-5 |
Greece
|
20210948
|
04/03/2021 19:23:50.0.0 |
39.86 |
21.59 |
10.0 |
39 |
|
5.5/19 |
6.5-7 |
Greece
|
20210974
|
05/03/2021 10:00:00.0.0 |
39.9 |
22.1 |
10.0 |
19 |
|
4.7/8 |
4.5-5 |
Greece
|
The focal mechanism solution of the origin for the earthquake of March 3 was calculated in GS RAS with signs of initial arrivals of P waves at 76 stations, including 19 stations which registered compression waves (plus signs) and 57 stations which registered tensile waves (minus signs). These stations are located in the interval of epicentral distances of 2.9-95.8º and in azymuth sector Az=3-357º. The focal mechanism solution in stereographic projection on the lower hemisphere and its elements are presented in the table. The table also contains focal mechanism solutions obtained at the USGS NEIC with W-phase Moment Tensor (Mww) technique and in Lamont-Dohert Earth Observatory of Columbia University, USA (LDEO GCMT) with СМТ (Centroid moment tensor) technique. Solutions from different centers are close. The earthquake occurred under the influence of prevailing tensile stresses oriented N-NE (AZ=31º) according to GS RAS, SW (AZ=224º) according to USGS NEIC and NE (AZ=42º) according to LDEO GCMT. NP1 plane strikes NW (STK=307-324º), NP2 – strikes E-SE (STK=104-119º) according to GS RAS and LDEO GCMT and SE (STK=139º) according to USGS NEIC, both planes are dipping to the horizon at close angles (DIP=36-55º). The type of motion along both planes – normal fault. The seismic moment was obtained in GS RAS from spectra of P waves registered at station "Talaya" (∆ 55.34º), it makes Mo=2.895*10**18 N*m, Mw=6.3. According to USGS NEIC Mo=3.335*10**18 N*m, Mww=6.3. According to LDEO GCMT Mo=3.14*10**18 N*m, Mw=6.3.
The focal mechanism solution of the origin for the earthquake of March 4 was calculated in GS RAS with signs of initial arrivals of P waves at 57 stations, including 19 stations which registered compression waves (plus signs) and 38 stations which registered tensile waves (minus signs). These stations are located in the interval of epicentral distances of 2.9-95.6º and in azymuth sector Az=13-342º. The focal mechanism solution in stereographic projection on the lower hemisphere and its elements are presented in the table. The table also shows the focal mechanism solutions obtained in the Deutsches GeoForschungsZentrum, Germany, GFZ. Solutions from different centers are close. The earthquake occurred under the influence of prevailing tensile stresses oriented SW (AZ=231-237º). NP1 plane strikes N-NW (STK=329-330º), NP2 strikes SE (STK=132-146º), both planes are dipping to the horizon at close angles (DIP=41-48º). The type of motion along both planes – normal fault. According to GFZ Mo=3.3*10**18 N*m, Mw=6.3.
Axes of main strengths |
Nodal planes |
Center |
|
T |
P |
N |
NP1 |
NP2 |
PI: 0
Azm: 31
|
PI: 72
Azm: 301
|
PI: 18
Azm: 121
|
Stk: 318
Dp: 48
Slip: 66
|
Stk: 104
Dp: 48
Slip: -114
|
GS RAS Federal research center, Geophysical survey of Russian Academy of Sciences
|
|
PI: 9
Azm: 224
|
PI: 79
Azm: 76
|
PI: 6
Azm: 315
|
Stk: 307
Dp: 36
Slip: -100
|
Stk: 139
Dp: 55
Slip: -83
|
NEIC National Earthquakes Information Center of US Geological Service
|
|
PI: 2
Azm: 42
|
PI: 77
Azm: 305
|
PI: 13
Azm: 132
|
Stk: 324
Dp: 48
Slip: -72
|
Stk: 119
Dp: 45
Slip: -109
|
GCMT Lamont-Doherty Earth Observatory Global CMT Columbia University, USA
|
|
PI: 0
Azm: 231
|
PI: 81
Azm: 323
|
PI: 9
Azm: 141
|
Stk: 330
Dp: 46
Slip: -77
|
Stk: 132
Dp: 46
Slip: -103
|
GS RAS Federal research center, Geophysical survey of Russian Academy of Sciences
|
|
PI: 3
Azm: 237
|
PI: 86
Azm: 38
|
PI: 1
Azm: 147
|
Stk: 329
Dp: 41
Slip: -88
|
Stk: 146
Dp: 48
Slip: -91
|
GFZ German Research Center for Geosciences
|
|
The earthquakes occurred 286-306 km SE of the strong earthquake on November 26, 2019 in Albania with a magnitude of M = 6.6. Then 51 people died, the number of victims was over 900 people. That earthquake completely destroyed 5.5 thousand houses, 28 schools and 146 enterprises.