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| Titel |
The link between great earthquakes and the subduction of oceanic fracture zones |
| VerfasserIn |
R. D. Müller, T. C. W. Landgrebe |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 3, no. 2 ; Nr. 3, no. 2 (2012-12-05), S.447-465 |
| Datensatznummer |
250001000
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| Publikation (Nr.) |
 copernicus.org/se-3-447-2012.pdf |
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| Zusammenfassung |
| Giant subduction earthquakes are known to occur in areas not previously
identified as prone to high seismic risk. This highlights the need to better
identify subduction zone segments potentially dominated by relatively long
(up to 1000 yr and more) recurrence times of giant earthquakes. We construct
a model for the geometry of subduction coupling zones and combine it with
global geophysical data sets to demonstrate that the occurrence of great
(magnitude ≥ 8) subduction earthquakes is strongly biased towards
regions associated with intersections of oceanic fracture zones and
subduction zones. We use a computational recommendation technology, a type of
information filtering system technique widely used in searching, sorting,
classifying, and filtering very large, statistically skewed data sets on the
Internet, to demonstrate a robust association and rule out a random effect.
Fracture zone–subduction zone intersection regions, representing only
25% of the global subduction coupling zone, are linked with 13 of the 15
largest (magnitude Mw ≥ 8.6) and half of the 50 largest
(magnitude Mw ≥ 8.4) earthquakes. In contrast, subducting
volcanic ridges and chains are only biased towards smaller earthquakes
(magnitude < 8). The associations captured by our statistical analysis
can be conceptually related to physical differences between subducting
fracture zones and volcanic chains/ridges. Fracture zones are characterised
by laterally continuous, uplifted ridges that represent normal ocean crust
with a high degree of structural integrity, causing strong, persistent
coupling in the subduction interface. Smaller volcanic ridges and chains have
a relatively fragile heterogeneous internal structure and are separated from
the underlying ocean crust by a detachment interface, resulting in weak
coupling and relatively small earthquakes, providing a conceptual basis for
the observed dichotomy. |
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