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| Titel |
Distributed power-law seismicity changes and crustal deformation in the SW Hellenic ARC |
| VerfasserIn |
A. Tzanis, F. Vallianatos |
| 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 ; 3, no. 3/4 ; Nr. 3, no. 3/4, S.179-195 |
| Datensatznummer |
250000676
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| Publikation (Nr.) |
 copernicus.org/nhess-3-179-2003.pdf |
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| Zusammenfassung |
| A region of definite
accelerating seismic release rates has been identified at the SW Hellenic
Arc and Trench system, of Peloponnesus, and to the south-west of the
island of Kythera (Greece). The identification was made after detailed,
parametric time-to-failure modelling on a 0.1° square grid over the area
20° E – 27° E and 34° N–38° N. The observations are strongly
suggestive of terminal-stage critical point behaviour (critical exponent
of the order of 0.25), leading to a large earthquake with magnitude 7.1 ±
0.4, to occur at time 2003.6 ± 0.6. In addition to the region of
accelerating seismic release rates, an adjacent region of decelerating
seismicity was also observed. The acceleration/deceleration pattern
appears in such a well structured and organised manner, which is strongly
suggestive of a causal relationship. An explanation may be that the
observed characteristics of distributed power-law seismicity changes may
be produced by stress transfer from a fault, to a region already subjected
to stress inhomogeneities, i.e. a region defined by the stress field
required to rupture a fault with a specified size, orientation and rake.
Around a fault that is going to rupture, there are bright spots (regions
of increasing stress) and stress shadows (regions relaxing stress);
whereas acceleration may be observed in bright spots, deceleration may be
expected in the shadows. We concluded that the observed seismic release
patterns can possibly be explained with a family of NE-SW oriented,
left-lateral, strike-slip to oblique-slip faults, located to the SW of
Kythera and Antikythera and capable of producing earthquakes with
magnitudes MS ~ 7. Time-to-failure modelling and empirical analysis of
earthquakes in the stress bright spots yield a critical exponent of the
order 0.25 as expected from theory, and a predicted magnitude and critical
time perfectly consistent with the figures given above. Although we have
determined an approximate location, time and magnitude, it is as yet
difficult to assert a prediction for reasons discussed in the text.
However, our results, as well as similar independent observations by
another research team, indicate that a strong earthquake may occur at the
SW Hellenic Arc, in the next few years. |
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