Earthquake Report: April 6, 2009, central Italy
Mobayen p., Ashari A., Eslami A.
1-Felt Reports
At 3:32 local time, an earthquake of Mw= 6.3 magnitude shock Aquila city, located at the northeast of Rome and in the center of Italy, Figure 1. According to the information centers, almost 300 people were killed, 1,000 injured and 10,000 buildings damaged or collapsed there. This earthquake was felt in a wide range of central Italy.
Figure 1: Epicenter of the Earthquake, 6/4/09, Aquila, Italy (www.emsc-csem.org).
This event is recorded by Iranian National Broad band Seismic Network (INSN) of IIEES, shown in figure 2. The distance between IIEES stations and the epicenter of this earthquake is almost 3000 km. Therefore, the recorded waveforms can be used effectively in studying the crustal structure and upper mantle, under the stations located in Iran, as well as the characteristics of seismic wave propagation. The three components of waveform data are found in www.iiees.ac.ir.
Figure 2: The vertical components, recorded by INSN at 18 stations
Many aftershocks accrued after the main shock in Aquila area, the most important of which are listed in Table1.
Table1: Aftershocks of Italy Earthquake (www.emsc-csem.org).
|
No |
Date & Time (UTC) |
Latitude |
Longitude |
Depth km |
Mag |
Region name |
|||
|
1 |
42.39 |
N |
13.38 |
E |
2 |
ML |
3.3 |
CENTRAL ITALY |
|
|
2 |
42.38 |
N |
13.38 |
E |
10 |
ML |
2.9 |
CENTRAL ITALY |
|
|
3 |
42.38 |
N |
13.39 |
E |
10 |
ML |
3.1 |
CENTRAL ITALY |
|
|
4 |
42.35 |
N |
13.36 |
E |
2 |
ML |
3.5 |
CENTRAL ITALY |
|
|
5 |
42.25 |
N |
13.48 |
E |
10 |
ML |
3.0 |
CENTRAL ITALY |
|
|
6 |
42.24 |
N |
13.48 |
E |
10 |
ML |
3.1 |
CENTRAL ITALY |
|
|
7 |
42.52 |
N |
13.34 |
E |
9 |
ML |
3.0 |
CENTRAL ITALY |
|
|
8 |
42.46 |
N |
13.35 |
E |
11 |
ML |
3.3 |
CENTRAL ITALY |
|
|
9 |
42.49 |
N |
13.42 |
E |
2 |
mb |
4.0 |
CENTRAL ITALY |
|
|
10 |
42.49 |
N |
13.26 |
E |
2 |
ML |
3.9 |
CENTRAL ITALY |
|
|
11 |
42.50 |
N |
13.26 |
E |
2 |
ML |
3.2 |
CENTRAL ITALY |
|
|
12 |
42.52 |
N |
13.35 |
E |
2 |
Mw |
5.2 |
CENTRAL ITALY |
|
|
15 |
42.31 |
N |
13.49 |
E |
10 |
ML |
3.2 |
CENTRAL ITALY |
|
|
16 |
42.33 |
N |
13.23 |
E |
40 |
ML |
4.0 |
CENTRAL ITALY |
|
|
17 |
42.38 |
N |
13.22 |
E |
2 |
ML |
3.9 |
CENTRAL ITALY |
|
|
18 |
42.30 |
N |
13.47 |
E |
10 |
ML |
3.0 |
CENTRAL ITALY |
|
|
19 |
42.36 |
N |
13.39 |
E |
9 |
ML |
3.0 |
CENTRAL ITALY |
|
|
20 |
42.52 |
N |
13.34 |
E |
10 |
ML |
4.0 |
CENTRAL ITALY |
|
|
21 |
42.45 |
N |
13.39 |
E |
2 |
mb |
4.3 |
CENTRAL ITALY |
|
|
22 |
42.50 |
N |
13.35 |
E |
11 |
ML |
3.2 |
CENTRAL ITALY |
|
|
23 |
42.51 |
N |
13.33 |
E |
10 |
ML |
3.1 |
CENTRAL ITALY |
|
|
24 |
42.35 |
N |
13.46 |
E |
2 |
mb |
4.3 |
CENTRAL ITALY |
|
|
25 |
42.53 |
N |
13.39 |
E |
2 |
Mw |
5.4 |
CENTRAL ITALY |
|
|
26 |
42.40 |
N |
13.27 |
E |
2 |
ML |
3.3 |
CENTRAL ITALY |
|
|
27 |
42.55 |
N |
13.34 |
E |
2 |
Mw |
4.1 |
CENTRAL ITALY |
|
|
28 |
42.36 |
N |
13.40 |
E |
9 |
ML |
3.2 |
CENTRAL ITALY |
|
|
29 |
42.35 |
N |
13.33 |
E |
11 |
ML |
3.5 |
CENTRAL ITALY |
|
|
30 |
42.35 |
N |
13.38 |
E |
9 |
ML |
3.1 |
CENTRAL ITALY |
|
|
31 |
42.30 |
N |
13.43 |
E |
2 |
ML |
4.0 |
CENTRAL ITALY |
|
|
32 |
42.27 |
N |
13.42 |
E |
2 |
ML |
3.7 |
CENTRAL ITALY |
|
|
33 |
42.33 |
N |
13.49 |
E |
9 |
ML |
3.0 |
CENTRAL ITALY |
|
|
34 |
42.28 |
N |
13.49 |
E |
10 |
ML |
3.1 |
CENTRAL ITALY |
|
|
35 |
42.36 |
N |
13.29 |
E |
2 |
ML |
3.7 |
CENTRAL ITALY |
|
|
36 |
42.34 |
N |
13.37 |
E |
2 |
mb |
4.5 |
CENTRAL ITALY |
|
|
38 |
42.30 |
N |
13.40 |
E |
13 |
Mw |
5.6 |
CENTRAL ITALY |
|
|
39 |
42.32 |
N |
13.40 |
E |
10 |
ML |
3.2 |
CENTRAL ITALY |
|
|
40 |
42.33 |
N |
13.36 |
E |
10 |
ML |
3.5 |
CENTRAL ITALY |
|
|
41 |
42.31 |
N |
13.35 |
E |
10 |
Mw |
5.0 |
CENTRAL ITALY |
|
|
42 |
42.39 |
N |
13.35 |
E |
2 |
ML |
3.2 |
CENTRAL ITALY |
|
|
43 |
42.38 |
N |
13.32 |
E |
11 |
ML |
3.0 |
CENTRAL ITALY |
|
|
44 |
42.48 |
N |
13.41 |
E |
2 |
Mw |
5.1 |
CENTRAL ITALY |
|
|
45 |
42.34 |
N |
13.23 |
E |
2 |
ML |
3.7 |
CENTRAL ITALY |
|
|
46 |
42.39 |
N |
13.30 |
E |
2 |
ML |
3.9 |
CENTRAL ITALY |
|
|
47 |
42.23 |
N |
13.43 |
E |
2 |
ML |
3.2 |
CENTRAL ITALY |
|
|
48 |
42.23 |
N |
13.43 |
E |
2 |
ML |
3.2 |
CENTRAL ITALY |
|
|
49 |
42.38 |
N |
13.32 |
E |
2 |
Mw |
4.4 |
CENTRAL ITALY |
|
|
50 |
42.24 |
N |
13.49 |
E |
10 |
ML |
3.2 |
CENTRAL ITALY |
|
|
51 |
42.34 |
N |
13.40 |
E |
10 |
ML |
3.5 |
CENTRAL ITALY |
|
|
52 |
42.31 |
N |
13.32 |
E |
2 |
ML |
3.5 |
CENTRAL ITALY |
|
|
53 |
42.32 |
N |
13.38 |
E |
10 |
ML |
3.1 |
CENTRAL ITALY |
|
|
54 |
42.47 |
N |
13.40 |
E |
30 |
mb |
4.4 |
CENTRAL ITALY |
|
|
55 |
42.30 |
N |
13.38 |
E |
8 |
ML |
3.0 |
CENTRAL ITALY |
|
|
56 |
42.48 |
N |
13.36 |
E |
4 |
ML |
3.1 |
CENTRAL ITALY |
|
|
57 |
42.33 |
N |
13.29 |
E |
2 |
ML |
3.9 |
CENTRAL ITALY |
|
|
58 |
42.39 |
N |
13.32 |
E |
10 |
ML |
3.2 |
CENTRAL ITALY |
|
|
59 |
42.38 |
N |
13.36 |
E |
10 |
ML |
3.0 |
CENTRAL ITALY |
|
|
60 |
42.38 |
N |
13.34 |
E |
10 |
mb |
4.5 |
CENTRAL ITALY |
|
|
61 |
42.33 |
N |
13.37 |
E |
9 |
ML |
3.1 |
CENTRAL ITALY |
|
|
63 |
42.34 |
N |
13.39 |
E |
9 |
ML |
2.8 |
CENTRAL ITALY |
|
|
64 |
42.33 |
N |
13.33 |
E |
9 |
ML |
2.8 |
CENTRAL ITALY |
|
|
65 |
42.37 |
N |
13.37 |
E |
9 |
ML |
3.2 |
CENTRAL ITALY |
|
|
66 |
42.30 |
N |
13.35 |
E |
10 |
ML |
3.2 |
CENTRAL ITALY |
|
|
67 |
42.41 |
N |
13.32 |
E |
2 |
Mw |
5.1 |
CENTRAL ITALY |
|
|
68 |
42.41 |
N |
13.39 |
E |
8 |
ML |
3.4 |
CENTRAL ITALY |
|
|
69 |
42.37 |
N |
13.23 |
E |
2 |
mb |
4.3 |
CENTRAL ITALY |
|
|
70 |
42.43 |
N |
13.36 |
E |
13 |
ML |
3.3 |
CENTRAL ITALY |
|
|
71 |
42.32 |
N |
13.46 |
E |
5 |
ML |
3.3 |
CENTRAL ITALY |
|
|
72 |
42.38 |
N |
13.32 |
E |
2 |
Mw |
6.3 |
CENTRAL ITALY |
|
|
73 |
42.33 |
N |
13.34 |
E |
2 |
ML |
3.5 |
CENTRAL ITALY |
|
|
75 |
42.36 |
N |
13.37 |
E |
2 |
ML |
4.0 |
CENTRAL ITALY |
|
|
77 |
42.33 |
N |
13.36 |
E |
9 |
ML |
3.0 |
CENTRAL ITALY |
|
2- Seismic History
Italy is one of the most seismically active countries in Europe (Figure 3). The Alps in the north of Italy are the result of African tectonic plate movement towards North into the Eurasian plate, a process that continues at a pace of 3cm a year.
Figure 3: Seismicity of Italy, 1990-2006 (adapted from USGS)
The movement of Adriatic Sea
microplate beneath the country's east coast seems to have contributed the
happening of this earthquake.
"On the basis of past seismicity in this area, the possibility of a further
event of similar magnitude cannot be ruled out," said Roger Musson, a
seismologist at the British Geological Survey.
Minor tremors are occurred frequently in Italy but experiencing such destructive
earthquakes is unusual there.
In 2002, more than 25 people were killed because of the quake in the southern
town of San Giuliano di Puglia which was the highest number of Italian
earthquake casualty in more than 20 years. In this earthquake more than 40,000
people lost their houses.
In 1980, more than 2,700 people were killed and several thousands were injured
because of the earthquake of about 6.9 magnitude. Its epicenter was at Eboli,
about 50 miles in the south of Naples.
One of most destructive earthquakes happened a century ago in 1908, killed as
many as 100,000 people in the Sicilian town of Messina in.Italy.
3- Tectonic Summary
The earthquake, 6th April
2009, occurred in Central Italy as a result of normal faulting on a NW-SE
oriented structure in the central Apennines, a mountain belt that runs from the
Gulf of Taranto in the south to southern edge of Po basin in the northern Italy.
The Apennine fold-and-Thrust belt of mainland Italy is an Africa-Verging
mountain chain belonging to the pri-Adriatic orogenic system. The overall
structure of this belt is the result of convergence between African and Eurasian
plates since late cretaceous.
The late collision between orogenic segments of the system (i.e. Tyrrhenia and
Adria) is responsible for the emplacement of Apenninie units during Miocene to
Pleistocene times.
In the Late Miocene to early Pleistocene, the Apennines were affected by
extension in the axial zone of the belt. This extension probably was resulted by
the contraction occurring at that time on the foreland side of orogen.
The evolution of this system has caused the expression of all different tectonic
styles acting at the same time in a broad region surrounding Italy and the
central Mediterranean.
The April 6th, 2009 earthquake, related to the normal faulting and east-west
extensional tectonics dominating the entire Apennine belt, is primarily a
response to the Tyrrhenian basin opening faster than the compression between
Eurasian and African plates.
4- References:
The Adria Microplate: GPS
Geodesy, Tectonics and Hazards., By Nicholas Pinter, Grenerczy Gyula, John
Weber, Seth Stein, Damir Medak
Published by Springer, 2006
ISBN 1402042345, 9781402042348
413 pages
http://www.guardian.co.uk/science/blog/2009/apr/06/natural-disasters-geology
http://earthquake.usgs.gov/eqcenter/eqinthenews/2009/us2009fcaf/#summary