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| Titel |
Vrancea slab earthquakes triggered by static stress transfer |
| VerfasserIn |
A. Ganas, B. Grecu, E. Batsi, M. Radulian |
| 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. 12 ; Nr. 10, no. 12 (2010-12-15), S.2565-2577 |
| Datensatznummer |
250008536
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| Publikation (Nr.) |
 copernicus.org/nhess-10-2565-2010.pdf |
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| Zusammenfassung |
| The purpose of this paper is to study the interaction of the Vrancea seismic
activity (Romania) in space as result of Coulomb, static stress transfer
during M=7+ events. In this area, three large events occurred in 1977, 1986
and 1990 at mid-lower, lithospheric depths and with similar focal mechanisms.
Assuming elastic rheology for the deforming rocks it is suggested that
frictional sliding on pre-existing fault produced the 1986 M=7.1 event
(depth 131 km), that was possibly triggered by the 1977 M=7.4 event (depth
94 km). We calculated a static stress transfer of 0.52–0.78 bar to the
hypocentre of the 1986 event. On the contrary, the occurrence of the 1990
event is uncertain: it is located inside the relaxed (shadow) zone of the
combined 1977 and 1986 static stress field considering an azimuth for maximum
compression of N307° E. It follows that, the 1990 earthquake most
likely represents an unbroken patch (asperity) of the 1977 rupture plane that
failed due to loading. However, if a different compression azimuth is assumed
(N323° E) then the 1990 event was also possibly triggered by static
stress transfer of the 1977 and 1986 events (combined). Our modeling is a
first-order approximation of the kind of earthquake interaction we might
expect at intermediate lithospheric depths (80–90 to 130–140 km). It is
also suggested that static stress transfer may explain the clustering of
Vrancea earthquakes in space by the rupturing of two (possibly three)
NW-dipping major zones of weakness (faults) which accommodate the extension
(vertical elongation) of the slab. |
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