Information message about the strong earthquake in Northern Italy on May 20, 2012 |
| The strong earthquake with M=6.1 has occurred in Northern Italy on May 20, 2012 at 2:03 GMT (6:03 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 12 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 52 stations, accurate processing - with data 58 stations. |
| Fig. 1 presents fragments of records obtained from digital stations Isparta (∆ 16º), Vasula (∆ 16.5º), Obninsk (∆ 19º), Kislovodsk (∆ 22.3º), Garni (∆ 25º). Fig. 2 presents fragments of records obtained from digital stations Arti (∆ 31.4º), Borovoe (∆ 38.5º), Kurchatov (∆ 44.1º), Tiksi (∆ 55.7º), Talaya (∆ 57.8º).
|
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 |
02-03-51.1 |
44.94 |
11.4 |
5 |
58 |
6.1/29 | 5.9/28 | 9.5-10 | 53 | IPC GS RAS (Accurate) | | 2 |
02-03-51.9 |
44.93 |
11.44 |
10 |
52 |
6.1/27 | 5.9/26 | 8.5-9 | 53 | IPC GS RAS (Preliminary) | | 3 |
02-03-53.0 |
44.9 |
11.24 |
10 |
1095 |
Mw 6.1 | | | 10 | CSEM | | 4 |
02-03-52.3 |
44.8 |
11.19 |
5.1 |
573 |
Mw 6 | 5.8/461 | | 14 | 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 epicenter of this earthquake which origin was located on the territory of north Italian region Emilia-Romagna at the depth of 5 km, 48 km N-N-E of Bologna, 95 km S-W of Venice and 184 km E-S-E of Milan. |
Figure 3 |
|
| Aftershock |
| GS RAS registered:
4 hours before the main shock - foreshock with M=4.5, within an hour after the main shock - 4 aftershocks with M>4, the last one with a magnitude M=5.2, 11 hours after the main shock - aftershock with a same magnitude M=5.2. Total registered 10 events in 18 hours. |
| N |
Date & Time (GMT)
yy-mm-dd hh:mm:sec |
Lat
degr. |
Lon
degr. |
Depth
km |
N
station |
Ms/ N |
mb/ N |
Io
calc. |
Region |
| 20122047 | 2012-05-19 23:13:27.0 | 44.96 | 11.21 | 10 | 15 | - | 4.5/ 13 | 4-4.5 | Northern Italy | | 20122050 | 2012-05-20 02:25:09.0 | 45.12 | 11.33 | 10 | 8 | - | 4.2/ 5 | 3.5 | Northern Italy | | 20122051 | 2012-05-20 02:29:57.0 | 44.45 | 11.37 | 10 | 9 | - | 4.1/ 7 | 3-3.5 | Northern Italy | | 20122052 | 2012-05-20 02:35:38.0 | 44.96 | 11.47 | 10 | 14 | - | 4.5/ 10 | 4-4.5 | Northern Italy | | 20122053 | 2012-05-20 03:02:50.0 | 44.98 | 11.38 | 10 | 47 | - | 5.2/ 25 | 5.5-6 | Northern Italy | | 20122063 | 2012-05-20 09:13:21.0 | 45 | 11.21 | 10 | 30 | - | 4.6/ 17 | 4.5 | Northern Italy | | 20122065 | 2012-05-20 10:12:20.0 | 44.89 | 11.26 | 10 | 14 | - | 4.4/ 6 | 4 | Northern Italy | | 20122060 | 2012-05-20 13:18:02.0 | 44.78 | 11.59 | 10 | 43 | - | 5.2/ 29 | 5.5-6 | Northern Italy | | 20122064 | 2012-05-20 17:37:13.0 | 44.97 | 11.24 | 10 | 22 | - | 4.7/ 12 | 4.5-5 | Northern Italy | |
| Macroseismic manifestations |
| ITAR TASS reported that after the earthquake 4 workers were killed under the debris of ceramics factory in the region of Ferrara town. Another two persons died from heart failure caused by the stress, including one lady from Germany who was on business trip to Italy and one 100 years old lady. 50 persons were injured. The rescue operation is still under way in the disaster area. In accordance with the Department of Civil Defense nearly 2,5 thousands of people were evacuated from Modena Province and 500 persons from Ferrara Province.
The new underground shock with magnitude 5,1 has occurred in the day time at the north of Italy, in Emilia-Romagna region, which alredy suffered from significant shock the night before. News channel "Cky-T-G-24" reported that underground shock was felt in numerous towns not only in Emilia-Romagna region, where the epicenter of this disaster was located, but also in the north-east of Apennines in the regions of Venice, Bolzano and even in Milan. This new shock led to collapse of buildings, which were damaged by the night shock, including middle ages towers, which have historical value.
There were no new reports about victims.
Fig. 4, taken from site of USGS NEIC , presents the USGS Community Internet Intensity Map by 1221 responses in 434 cities.
|
Figure 4 |
|
| Historical records |
| Epicenter of this earthquake was located 315 km. N-W of epicenter of destructive earthquake which occurred on April 6, 2009 in l'Aquila. |
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism of the earthquake on May 20, 2012 at 02:03 was calculated by IPC GS RAS with signs of initial arrivals of P-waves at 68 stations, including 9 of them which registered compression waves (“plus” signs), and 59 stations which registered extension waves (“minus” signs). These stations are located within 14–85º interval of epicentral distances and are distributed rather uniformly as regards to their azimuths to the epicenter. Fault plane solutions in stereographic projection at lower hemisphere are presented at Figure 5, elements of the solutions are presented in Table 2. Table 2 and Figures 6, 7 also present solutions obtained with Centroid Moment Solution technique in Harvard Center, USGS NEIC, and with Centroid Moment Tensor technique from Quick CMT Catalog, USA.
The solutions obtained in various centers are identical. This earthquake has occurred under the action of compression stresses oriented S-S-W in case of IPC GS RAS solution and N-N-E in case of USGS NEIC and Quick CMT solutions. Type of motion in the origin is a reverse fault with insignificant strike-slip component. One nodal plane (NP1) is oriented in near-latitudinal direction (Stk=256, 270, 96º), another one (NP2) has SE or NW strike (Stk=126, 119, 302º). Both nodal planes have close angles of dipping (DP=35-58º). Seismic moment of this earthquake obtained in IPC GS RAS with Р-wave spectra at «Arti» station (∆ 31.38º) makes Мо=2.6*10**18 N*m. Average value of moment magnitude was calculated with Kanamori formula and makes Mw=6.2. In accordance with USGS NEIC Мо=1.2*10**18 N*m, Mw=6.0, in accordance with Quick CMT catalogue Мо=1.66*10**18 N*m, 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 |
| | | |
| | | | | |
| | IPC GS RAS | | 75 | 113 | 2 | 14 |
15 | 284 | 270 | 49 | 70 | 119 |
45 | 112 | NEIC | | 73 | 249 | 12 | 21 |
12 | 114 | 96 | 35 | 68 | 302 |
58 | 105 | 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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