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Titel |
Strong foreshock signal preceding the L'Aquila (Italy) earthquake (Mw 6.3) of 6 April 2009 |
VerfasserIn |
G. A. Papadopoulos, M. Charalampakis, A. Fokaefs, G. Minadakis |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1561-8633
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Digitales Dokument |
URL |
Erschienen |
In: Natural Hazards and Earth System Science ; 10, no. 1 ; Nr. 10, no. 1 (2010-01-11), S.19-24 |
Datensatznummer |
250007872
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Publikation (Nr.) |
copernicus.org/nhess-10-19-2010.pdf |
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Zusammenfassung |
We used the earthquake catalogue of INGV extending from 1 January 2006 to
30 June 2009 to detect significant changes before and after the 6 April 2009
L'Aquila mainshock (Mw=6.3) in the seismicity rate, r (events/day), and in
b-value. The statistical z-test and Utsu-test were applied to identify
significant changes. From the beginning of 2006 up to the end of October 2008
the activity was relatively stable and remained in the state of
background seismicity (r=1.14, b=1.09). From 28 October 2008 up to 26 March 2009,
r increased significantly to 2.52 indicating weak foreshock sequence;
the b-value did not changed significantly. The weak foreshock sequence was
spatially distributed within the entire seismogenic area. In the last 10 days
before the mainshock, strong foreshock signal became evident in space
(dense epicenter concentration in the hanging-wall of the Paganica fault), in
time (drastic increase of r to 21.70 events/day) and in size (b-value dropped
significantly to 0.68). The significantly high seismicity rate and the low b-value
in the entire foreshock sequence make a substantial difference from the
background seismicity. Also, the b-value of the strong foreshock stage (last
10 days before mainshock) was significantly lower than that in the
aftershock sequence. Our results indicate the important value of the
foreshock sequences for the prediction of the mainshock. |
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